UC-NRLF 
 
 51fl 
 
SCIENTIFIC MEMOIRS, 
 
 SELECTED FROM 
 
 THE TRANSACTIONS OF 
 
 FOREIGN ACADEMIES OF SCIENCE, 
 
 AND FROM 
 
 FOREIGN JOURNALS, 
 
 NATURAL HISTORY. 
 
 EDITED BY 
 
 ARTHUR HENFREY, F.R.S., F.L.S. &c., 
 
 LECTURER ON BOTANY AT ST. GEORGE'S HOSPITAL, 
 AND 
 
 THOMAS HENRY HUXLEY, F.R.S. 
 
 LONDON: 
 
 TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET, 
 Printers and Publishers to the University of London. 
 
 1853. 
 
FLAMMAM. 
 
 " Every translator ought to regard himself as a broker in the great intellectua 
 traffic of the world, and to consider it his business to promote the barter of the pro 
 duce of mind. For, whatever people may say of the inadequacy of translation, -it is 
 and must ever be, one of the most important and meritorious occupations in the greal 
 commerce of the human race." Goethe, Kunst und Alterthum. 
 
CONTENTS. 
 
 PART I. 
 
 Page 
 ART. I. On the Circulation of Sap in Plants. By Dr. HERMANN 
 
 HOFFMANN 1 
 
 ART. II. Upon the Male of Argonauta Argo and the Hectocotyli. 
 
 By Professor HEINRICH MULLER of Wiirzburg 52 
 
 ART. III. A few Remarks upon Hectocotylus. By C. TH. VON 
 
 SIEBOLD, Professor at the University of Breslau 92 
 
 ART. IV. Investigation of the Question : Does Cellulose form 
 the basis of all Vegetable Membranes? By HUGO VON 
 MOHL. 95 
 
 PART II. 
 
 ART. IV. Investigation of the Question : Does Cellulose form 
 the basis of all Vegetable Membranes ? By HUGO VON 
 MOHL (continued) 97 
 
 ART. V. Memoir upon the Hectocotyli and the Males of certain 
 
 Cephalopods. By MM. J. B. VERANY and C. VOGT. ...... 119 
 
 ART. VI. Organographical Observations on certain Epigynous 
 
 Monocotyledons. By H. CRUGER, of Trinidad 155 
 
 ART. VII. Fragments relating to Philosophical Zoology. Se- 
 lected from the Works of K. E. VON BAER . . 1 70 
 
IV CONTENTS. 
 
 PART III. 
 
 Page 
 
 ART. VII. Fragments relating to Philosophical Zoology. Se- 
 lected from the Works of K. E. VON BAER (continued) 193 
 
 ART. VIII. On the Development of Zostera. By W. HOF- 
 
 MEISTER 239 
 
 ART. IX. On the Winding of Leaves. By M. WICHURA 262 
 
 PART IV. 
 
 ART. IX. On the Winding of Leaves. By M. WICHURA (con- 
 tinued) 273 
 
 ART. X. On the Development of the Ascidians. By A. KROHN 312 
 
 ART. XI. Observations on the Development of the Pectini- 
 
 branchiata. By MM. KOREN and DANIELSSEN 330 
 
 TWELVE PLATES. 
 
SCIENTIFIC MEMOIRS. 
 
 NATURAL HISTORY. 
 
 ARTICLE I. 
 
 On the Circulation of Sap in Plants. 
 By Dr. HERMANN HOFFMANN. 
 
 [From the Botanische Zeitung , vol. vi. p. 377, 1848; vol. viii. p. 17 et seq. 18. r >0.] 
 
 , in animal physiology, many of the commonest vital phae- 
 nomena were involved in obscurity previous to Harvey's great 
 discovery of the circulation of the blood, so in the physiology of 
 plants^ not a few points are still inexplicable on account of our 
 very meagre acquaintance with the nature of the circulation of 
 the saps in vegetables. 
 
 Every Manual of Botany gives a different view as to the 
 anatomical system in which the saps are supposed to ascend or 
 descend : many deny altogether the descent of the fluids, while 
 others are so firmly convinced of the existence of this, that they 
 have made it the basis of a peculiar kind of descending growth 
 of roots, and stated that trees grow from above downwards, in- 
 stead of upwards from below. We are likewise ignorant of the 
 relations of the milk-sap to the other juices and to crude 
 nutrient saps, so that it is still undecided whether it is to be 
 
 SCIEN. MEM. Nat. Hist. VOL. I. PART I. 1 
 
2 HOFFMANN ON THE CIRCULATION 
 
 regarded as a secretion, or as a circulating nutrient fluid analo- 
 gous to blood. Even the function of the air-vessels is not 
 clearly made out, or, otherwise, the recent statement, that the 
 " so-called air-vessels " of the Ferns do not convey air, could not 
 have been made. Under such circumstances, it can only be 
 expected that the imperfect knowledge of the actual facts must 
 leave the cause of the movement of the sap in utter uncertainty; 
 and, indeed, on this very point the most wonderful notions are 
 current, capillarity, contractility, and endosmose have to do 
 duty in turn, as far as they will go. 
 
 Where is the crude nutrient sap elaborated ? How does it 
 arrive there ? By what path is it carried back to the other parts 
 of the plant to furnish the material for development ? In what 
 anatomical and physiological relation do the air-vessels stand to 
 the system in which the saps circulate ? 
 
 Injections cannot be applied in the endeavour to trace the 
 paths by which fluids penetrate the vegetable tissues, on account 
 of the minute size of the vessels, nor, indeed, without destruc- 
 tion of the substance. But the spontaneous absorption of easily 
 detected fluids accomplishes in plants what is done by injection 
 in human anatomy. Coloured fluids, however, are rarely taken 
 up by uninjured roots ; I have therefore made use of a very 
 dilute solution of ferrocyanide of potassium, which may be readily 
 detected in any spot to which it has penetrated, by the blue 
 colour it assumes when chloride of iron is applied. And as the 
 Prussian blue thus formed is insoluble in aqueous fluids, a little 
 care in slicing and preparing the objects enables us to avoid the 
 spreading of the colour to unaffected parts, which would deceive 
 the observer as to the boundaries within which the natural mo- 
 tion of the sap takes place. 
 
 In the first place, it is found that this fluid penetrates by a 
 different path in uninjured roots, from that which it takes when 
 the solution is caused to be absorbed directly by the cut surface 
 of a cut plant ; in the next place, that the course which this 
 fluid pursues is constantly the same, and peculiar to each plant; 
 and, moreover, that by no means all cells and vessels take equal 
 share therein, but that where, in general, vessels are met Avith, 
 the sap enters first into these,, and then, as in animals, passes far 
 more slowly from these into all the remaining tissues of the plant. 
 
OF SAP IN PLANTS. 3 
 
 By this means it is possible to test, by direct experiment, the 
 directions and course of the flowing saps from the root to the 
 leaves, and backwards to all the other organs, which the follow- 
 ing observations attempt to do in regard to the more important 
 families of plants. 
 
 I. ACOTYLEDONS. 
 
 1. Fungi. 
 
 Clavaria rugosa, Bull. A number of these fungi (with unin- 
 jured radical filaments imbedded in earth) were placed with the 
 lowest part in an aqueous solution of ferrocyanide of potassium : 
 in twenty-four hours they had become thoroughly imbued with 
 it, so that a blue colour was produced when the tips were merely 
 slightly touched with chloride of iron. 
 
 When a cross section of the upper part of the fungus was 
 made, and the surface of this tested, a blue colour was also pro- 
 duced, but of very different intensity in different parts of the 
 section. One part remained almost white, while the central 
 portion, as well as a zone within the layer of rind, was strongly 
 coloured : the hymenial layer was tinged but very slightly, which 
 appears to depend partly on the great density of the cellular 
 tissue, offering more resistance to the passage of the juices, and 
 partly on the similar effect of the horizontal position of its cells. 
 The cells of the interior were of perfectly similar character, 
 but they seemed to be more loosely packed under the cortical 
 layer and in the central part, and the more active conduction of 
 the fluid is connected w r ith this. The walls of the cells, and 
 also the fluid between them, were coloured blue. Longitudinal 
 sections exhibited exactly the same results. 
 
 Scaphophorum agaricoides, Ehrb. The little branch to which 
 the fungus was attached was dipped into the fluid, without 
 wetting the fungus itself. In twenty-four hours the fluid had 
 made its way to about the middle of the fungus ; when chlo- 
 ride of iron w r as dropped on the surface, a blue colour was 
 produced, and this arrested the further penetration of the ferro- 
 cyanide of potassium toward the border, so that the latter did 
 not exhibit any reaction even after two days. 
 
 Although this fungus is composed of uniform elementary 
 structures, the reaction of the different layers displayed very 
 
 1* 
 
4 HOFFMANN ON THE CIRCULATION 
 
 unequal intensity ; for while the sections of the lamellae were 
 still white, an intense blue was shown in the angles of their 
 folds ; the fleshy substance in the vicinity was likewise white, 
 while the same exhibited two strongly coloured layers farther 
 up ; the superficial layer was also coloured deep blue. Micro- 
 scopical examination showed that the lower part of the cellular 
 tissue which had remained white was more closely packed, with 
 predominant transverse joints, whence the fluid could not pass 
 so readily ; while the upper part, distinguished by its deep colour, 
 facilitated the penetration by the laxity and the varied direction 
 of its cells. 
 
 Trametes suaveolens, Fries. Several drops of the test fluid 
 were poured upon the bark of the willow stem upon which the 
 fungus grew, near the point of attachment, but without wetting 
 the plant itself. In two days the fungus exhibited a tinge of 
 blue, chiefly at the places where it was attached to the slice of 
 bark, and consequently it must itself have contained a salt of the 
 oxide of iron ; this slight blue colour was also visible on the out- 
 side of uninjured fungi. On the application of chloride of iron 
 to the surface of perpendicular sections, the colour became deeper 
 near the base, and spread somewhat farther, especially in one 
 point as far as the hymenial layer. 
 
 Agaricus virgineus y Pers. The patch of turf on which it grew 
 was placed in the fluid, and within three hours the entire fungus 
 was penetrated by the latter, which is not wonderfnl considering 
 the great moisture of the plant. Stipe, pileus, flesh, and gills, 
 were coloured deep blue in the reaction, the pileus darkest at 
 the part where it is continuous with the hollow stipe, while the 
 sections of the gills were only weakly tinged, or did not become 
 coloured at all ; but the passage of the blue-coloured into the 
 uncoloured parts was quite gradual, and exhibited no distinctly 
 marked boundaries. Examination by the microscope revealed 
 a very lax interwoven cellular tissue ; in the lighter spots, cells 
 were seen only half coloured blue, so that the fluid had not com- 
 pletely penetrated them. 
 
 From the foregoing it appears that the path of the circulation 
 has no accurately fixed boundaries in the Fungi, and presents no 
 anatomical peculiarities ; the fluid penetrates forwards and late- 
 rally between and in the cells, proceeding most rapidly in those 
 
OF SAP IN PLANTS. 5 
 
 places where the laxity of the tissue and the direction of the 
 cells oppose the smallest amount of resistance ; just as in blotting 
 or other unsized paper. 
 
 2. Lichens. 
 
 Cladonia subulata t Wallr. The lumps of earth on which the 
 plant grew were placed in the test fluid, and the whole was 
 covered with a plate of g ] ass, in order to maintain a moist atmo- 
 sphere. Yet even after ten days the plant was not permeated 
 throughout ; it had become coloured blue in some places, which 
 indicated a natural existence of salts of oxide of iron in it. After 
 the application of chloride of iron, moreover, to various sections, 
 only a slightly deeper blue colour presented itself, which is 
 readily explained by the extraordinary density of the tissue, and 
 the consequent slow conduction of the juices in the lichen, which 
 is itself of a rather dry nature. The blue colouring was uniform, 
 and exhibited no marked limits. 
 
 3. Mosses. 
 
 Syntrichia ruralis. The moss and the soil supporting it were 
 so placed in the fluid that the former remained unwetted ; the 
 atmosphere was kept damp as above. The stem conveyed the 
 fluid upwards ; the leaves exhibited an uniform blue colouring 
 at the base, which however spread very slowly over the surface, 
 when the chloride of iron was dropped upon them ; the fluid 
 advanced much more rapidly towards the point in a row of cells 
 lying close beside the margin, while the mid-nerve acquired no 
 perceptible colour. The chlorophyll granules did not seem to 
 exert any especial influence on this conduction, since the lowest 
 cells appeared coloured uniformly blue, in spite of their total 
 absence. In the cells lying somewhat higher up, the blue colour 
 did indeed correspond with the heaps of chlorophyll, which was 
 perhaps only an optical phenomenon : further up the cells were 
 pure green. 
 
 Barbula muralis^ Timm. Treated as above : half mature, like 
 the foregoing. Here again a blue stripe of more delicate cells 
 was seen along the margin up to the apex, after the application 
 of the reagent, while no discoloration could be detected in the 
 mid-nerve, and on the general surface of the parenchyma of the 
 leaf only isolated spots occurred, appearing to indicate a very 
 
6 HOFFMANN ON THE CIRCULATION 
 
 imperfect conduction of the sap in these places. The fruit-stalk 
 absorbed only a small portion of the fluid extremely slowly ; 
 when cut across, and the cut surface dipped in the solution of 
 ferrocyanide of potassium, it soon exhibited a very distinct re- 
 action ; strongest below, where rind and pith were coloured ; 
 weaker above, where only the pith was acted on (and this 
 slightly). 
 
 From this it appears that the passage of the sap goes on 
 chiefly and most energetically in a peculiar layer of cells along 
 the margins of the leaves, in these mosses, while the mid-nerve 
 fulfils another function ; I could not detect air in the latter. The 
 stem and the fruit- stalk conveyed fluid onward through all their 
 tissues, but very slowly so long as they remained uninjured. 
 When chloride of iron was applied to the uninjured rind, it pe- 
 netrated extremely slowly, which is sufficiently explained by the 
 solidity of the structure. 
 
 Hypnum cupressiforme, L. In this there are no peculiarly- 
 formed marginal cells and no mid-nerve ; and no definite direction 
 of the course of the sap could be detected here. This plant 
 became gradually saturated with the fluid, so that even the 
 peristome was coloured blue. 
 
 4. Ferns. 
 
 Pteris serrulata. The test fluid was dropped upon the mould 
 in which the plant was rooted, without wetting or injuring the 
 latter. In twenty-four hours it had already penetrated far up 
 the petiole ; the reagent did not colour the brown internal layer 
 or the vascular bundle in the central point ; the latter was white, 
 surrounded by brown soft cells. The parenchyma was blue and 
 rich in granules (chlorophyll and starch?) throughout. The 
 scalariform vessels in the interior distinctly contained air, and 
 when uninjured took up no test fluid, although the plant was in 
 a most vigorous condition of growth. 
 
 Polypodium crassifolium. Treated like the preceding. In 
 twenty-four hours the petiole was permeated by the fluid, and both 
 the rather delicate cortical layer (of a green colour), containing 
 no chlorophyll, and the entire parenchyma, which contained 
 very numerous granules, were coloured blue by the reagent. 
 The latter is traversed in the inner parts by isolated vascular 
 
OF SAP IN PLANTS. / 
 
 bundles which are surrounded and supported by a hard brown 
 layer of cells of a glass-like brittleness. These were not coloured 
 blue ; neither were the vessels in their centre, which evidently 
 contained air, and were to a slight extent unreliable. When 
 this petiole was cut across and the open end dipped in the test 
 fluid, the latter penetrated very rapidly upward into the white 
 air-vessels, driving out the air. If the upper part of the leaf was 
 clipped in the fluid, the phenomena were the same as in the first 
 case; under such circumstances nothing penetrated into the 
 air-vessels, which consequently are nowhere in communication 
 with the surface (the stomates). 
 
 Aspidium capense. The phenomena were exactly the same 
 as in the preceding instance. Here again the stomates on the 
 under side of the leaf conveyed no fluid into the air-vessels in 
 the interior. 
 
 Aspidium filix mas, Sw. The results did not differ from the 
 foregoing. The brown cells again w r ere not coloured blue here. 
 Hence the Ferns possess distinctly separate paths for the diffu- 
 sion of air and sap. I could not observe any special path for 
 the descending juices, and the existence of such may indeed be 
 doubted, since these plants are supposed to grow only at the 
 points. 
 
 II. MONOCOTYLEDONS. 
 
 In the preceding section an attempt was made to prove that 
 in the lower cellular plants, in accordance with their homogeneous 
 structure, the fluids passing from the soil into the plants, took 
 no fixed direction, but, soaking through from cell to cell, ad- 
 vanced most rapidly w r herever the laxity of the tissue opposed 
 the minimum of resistance. In the Vascular Cryptogams, on 
 the contrary, in the Ferns, it was found that special organs, 
 the streaked vessels, already present themselves, exclusively des- 
 tined to contain gaseous fluids, while the fluids absorbed from 
 the earth first ascended within the looser cellular tissue in the 
 vicinity of those vessels, and w r ere from thence diffused through- 
 out the remainder of the tissues of the vegetable ; not indeed 
 without previously undergoing suitable elaboration and ame- 
 lioration. 
 
 In the Monocotyledonous plants, where the specialization of 
 the anatomical systems becomes more distinctly marked, similar 
 
HOFFMANN ON THE CIRCULATION 
 
 results are met with, and it is especially seen here, that the 
 function ordinarily attributed to the system of the spiral vessels 
 and their allies, is devoid of all proof in fact, and has been de- 
 duced from experiments in which sufficient regard was not paid 
 to all the circumstances involved. At the conclusion of the 
 third part of this essay, relating to the Dicotyledons, I shall 
 examine these experiments more closely, and seek to demon- 
 strate the causes which have so long restricted us to conjectures 
 and opinions, in a matter which appears so simple. 
 
 Since in the plants now to be considered, new organs } flowers, 
 organs of fructification, and ovules, are added to those already 
 examined ; since, moreover, a far greater variety becomes evident 
 in the forms of the internal structure, and the physiological rela- 
 tions of the roots, stem, leaves, &c., of the Monocotyledons, 
 than exists in the majority of the Acotyledons ; the observation 
 of the progress of the sap within these different structures, pos- 
 sessing peculiar forms in the diverse families, acquires greater 
 importance, and admits of conclusions of a far more compre- 
 hensive nature. I therefore take permission to enter more 
 minutely into the details, in order to introduce the more extended 
 remarks in fitting places. 
 
 The experiments, as in the above-mentioned cases, w r ere made, 
 with the exception of Canna, on pot plants alone, which were 
 treated in the ordinary manner. In order to discover the course 
 of the sap, the earth was watered with a solution (always of 
 pretty equal concentration) of ferrocyanide of potassium, and 
 then, after this fluid had been absorbed by the uninjured roots, 
 the parts where absorption had occurred were demonstrated in 
 transverse and longitudinal sections of the plants^ by means of 
 sulphate of peroxide of iron. 
 
 Anomatheca cruenta, Lindl. (Iridaceae). Watered on the 16th 
 of July ; in two hours the ferrocyanide of potassium could be 
 detected in the bulbs, while it was sought in vain in the stems. 
 In the petals also (even in those developed subsequently to the 
 watering and investigated three weeks after), the sap could not 
 be traced, although at first appearance it seemed to have entered 
 them, since they contain a red colouring matter which is readily 
 decomposed and changed into a blue colour; but a counter- 
 experiment with pure water, with a careful application of the 
 
OF SAP IN PLANTS. 9 
 
 reagent to the petals (stripped of some of the epidermis by 
 shaving with a razor), showed the error of the first conjecture. 
 Into the sepals of the specimen, on the contrary, the sap 
 ascended within a few days ; the same occurred in some half-ripe 
 fruits which existed upon other specimens. The following is a 
 detailed account of the anatomical conditions. 
 
 The bulb does not consist of separate scales, but forms a kind 
 of tuber which is chiefly composed of a perfectly homogeneous 
 mass abounding in starch ; the outer coat is a reticulated shell 
 composed of two membranes : a thick bundle of vascular cords 
 runs up the centre. The starchy parenchyma does not react 
 blue, neither does the vascular mass in the centre, in the separate 
 vessels of which air may be detected by the microscope ; but a 
 very dark blue colour was seen in innumerable closely-crowded 
 little points in the cortical layer or shell. And the presence of 
 the ferrocyanide in the cortical substance did not depend upon 
 a penetration from without during the watering of the specimen, 
 and thus upon a penetration into the interior by an unusual 
 path ; for the outer coating of all showed 110 reaction whatever 
 with the salt of iron, while the blue colour was scarcely per- 
 ceptible inside the finest of the root-fibrils. The shell of the 
 bulb contains no air-vessels or spiral structures, but is traversed 
 in all directions by numerous anastomosing liber bundles, 
 which are sharply defined against the looser cellular substance 
 surrounding them, and give the shell the open reticulated aspect 
 already mentioned. These liber bundles exhibited no reaction ; 
 in the transverse section they look like large yellowish circles, 
 which are clearly contrasted against the surrounding blue cel- 
 lular spots. The cells lying between these bundles are of two 
 kinds ; those lying next them are narrower, more slender and 
 more elongated than the rest, which exhibit a rounded four- or 
 five-angled form ; it was these elongated cells which were coloured 
 blue by the application of the salt of iron, while the remaining 
 cells remained for the most part altogether uncoloured. The 
 blue-coloured cells frequently lie several one behind the other, 
 so that it is easy to trace the straight line in which the sap ad- 
 vances, without deviating to the side ; in other cases, especially 
 in the rest of the parenchyma, they frequently lie isolated, 
 whence it appears to follow, that the motion of the sap is not 
 
10 HOFFMANN ON THE CIRCULATION 
 
 only less perfect in general here, but also takes place in an irre- 
 gular manner, by no means in one and the same plane (parallel 
 to the surface of the section). This tuberous bulb is, evidently, 
 remarkably well fitted to afford a clear notion of the organs con- 
 veying the sap in plants, since here all the important parts, the 
 spiroids, the parenchyma, the elongated vessels, and the liber, 
 are distinctly, and in fact as in the Dicotyledons widely sepa- 
 rated from each other, to the great convenience of the observer. 
 
 Underneath the bulb is the true root, which is of a pointed 
 conical form. Here also the vascular bundles lie in the middle, 
 while the blue colouring occurred in the parts more toward the 
 circumference. In the stem no discoloration could be perceived, 
 even in the cases where distinct reaction occurred, not only in 
 the bulb below, but also in the capsule at the upper end. From 
 this it seems as if the absorbed sap rested or became accu- 
 mulated in particular parts of the plant, while it only hurried 
 through the others as passages. In the cases where reaction 
 was observed in the calyx, microscopical examination showed 
 that the air-carrying, delicate unreliable spiral vessels or annular 
 vessels were never the organs conveying the sap, but the elon- 
 gated cells often lying close beside them. In specimens which 
 were taken up nine days after watering, the absorbed ferrocyanide 
 could be detected inside the half-ripe, otherwise fully-developed, 
 capsules. It occurred within the elongated cells, which always 
 accompanied the numerous delicate air-vessels in the axis, and 
 seen through a lens after the reaction, formed a great abundance 
 of little blue points and streaks. The soft, unripe seeds also exhi- 
 bited distinct reaction in particular places ; here the fluid had 
 also been conveyed from cell to cell through the seeds ; no 
 vessels of any kind exist in the seeds. 
 
 Tigridia pavonia, Pers. (Iridaceae). The plant was watered 
 with the ferrocyanide while in full vegetation, on the 25th of 
 July. After six days the reaction was observable not only in the 
 bulb but also throughout the whole stem up to the floral organs, 
 but not in these or in the interior of the germen. In nine days, 
 however, the germen also had absorbed the salt, close beneath 
 the surface, but neither the interior nor the ovules exhibited any 
 reaction. The current had advanced more externally to the 
 upper parts, to supply the floral organs with sap in the first 
 
OF SAP IN PLANTS. 11 
 
 instance, since a strong influx of sap and an active vegetation 
 do not exist in the ovary and the ovules until they are fully 
 developed. In the flower- bud of a blossom unfolded on the 
 same day, the reaction could be detected in the petals, the 
 stamens and in the pistil up to the stigma. The root : this is 
 placed underneath the bulb, and is of a swollen conical form. 
 Internally it is homogeneous, and in the centre is found the 
 bundle of striped vessels ; the blue colour was seen to a slight 
 extent surrounding this, but much more marked at the peri- 
 pherical layer. Bulb : it consists of the bases of some six stems, 
 enveloped by the sheaths at the bases of leaves ; the vascular 
 bundles are scattered irregularly in the former; no reaction 
 could be detected in the bases of the stems. Inside the bulb- 
 scales the vascular bundles lie at some distance from each other 
 in the median layer, while the reaction brought out a great 
 number of blue spots, both in the mesophyllum and, more espe- 
 cially, beneath the inner and outer epidermis of the bulb-scales. 
 In the outermost coats of the bulb the blue colour was not 
 limited to isolated points, but diffused uniformly throughout the 
 entire mesophyllum, with the exception of the vessels. Micro- 
 scopical examination of longitudinal sections showed that the 
 vessels contained air and were uncoloured, while the cellular 
 tissue and especially a portion of the elongated laxer cells were 
 coloured deep blue. It is remarkable that only a portion and 
 not the whole of the elongated vessels were concerned in the first 
 conveyance of the sap. In longitudinal sections it was seen that 
 these cells were much more easily separated from each other 
 laterally than at their ends, by pressure, which seems not unim- 
 portant in reference to the conveyance of the sap. Stem : in a 
 cross section half-way between two nodes, the reaction made 
 visible a large number of blue points, both inside the cortical 
 layer and in the layers of the central parenchyma. The cortical 
 layer is composed of few, narrow, striped vessels, liber bundles 
 with very long cells colourless as glass, and of elongated cells 
 which were in part coloured blue ; the layer allied to liber found 
 at the circumference of the central parenchymatous substance 
 of the stem, which is very thick in the internodes, while it is far 
 weaker at the nodes, did not become coloured. The vascular 
 bundles are scattered in the internal substance and were not 
 
12 HOFFMANN ON THE CIRCULATION 
 
 coloured ; they are connected with the compact parenchyma- 
 tous cellular tissue by a lax tissue of delicate prosenchymatous 
 cells, forming an investment around them. When the prepa- 
 ration was dried these were partially torn away, and the vascular 
 bundles hung loose in the tubular cavities thus produced. In 
 longitudinal sections the vascular bundles were seen most di- 
 stinctly of a yellowish colour ; between and beside these the blue 
 streaks and points which indicated the sap -bearing cellular tissue. 
 Flower : when the epidermis had been removed it was easy to 
 detect the reaction here also, and it was seen uniformly through- 
 out the parenchyma (containing colouring matter) of the petals, 
 while the vessels and the delicate parenchymatous cells accom- 
 panying them remained free. The stamens, conjoined into a 
 tube, in the angles of which two vascular bundles are found, 
 exhibited blue points both at their inner and outer boundaries, 
 while the style lying free in the tube of the filaments was only 
 spotted with blue in its outer periphery. The stigma was found 
 very uniformly permeated with the salt. 
 
 Dioscorea bulbifera, L. (Dioscoreaceae) . Within seven days 
 after the watering the salt had already ascended five feet up in 
 the stem. Root : upon reacting on a longitudinal section the 
 whole tuber was found spotted with blue points and streaks ; no 
 colouring occurred in the yellowish-white pieces of vascular 
 bundles, which, composed of striped vessels containing air, were 
 visible here and there, nor in a considerable number of reddish 
 spots which microscopic examination proved to depend upon 
 large drops of yellowish red oil occurring in many of the cells. 
 The blue was seen inside the parenchyma of which the tuber is 
 almost exclusively formed, in the same cells which contained 
 starch. In a cross section of the Stem are seen a number of 
 small and also very large vessels not combined into bundles. 
 The larger are in many places situated at pretty regular di- 
 stances, forming something like a hexagonal figure in the paren- 
 chyma of the stem, while the small are scattered quite irregularly, 
 and often enveloped in a pretty thick coat of elongated cells. 
 Inside the central parenchyma or pith occurred isolated blue 
 points ; the broad woody layer on the contrary was wholly devoid 
 both of these and also of vessels, while by far the greatest mass 
 of the salt had ascended in the elongated cells of the liber and 
 
OP SAP IN PLANTS. 13 
 
 cortical layers, and had become more or less diffused from thence 
 into the surrounding parenchyma of the rind. The large vessels 
 of the stem just mentioned are of so great diameter that a hair 
 may be easily passed more than an inch down them. When the 
 stem was cut up, some of the fluid almost always escaped from 
 the wounded sap-bearing cells of the circumference and pene- 
 trated into the interior, as also in the garden balsam, where 
 the size and transparency of the tracheae invite such experi- 
 ments, giving an appearance as if these canals were not really 
 air-vessels but sap-conduits. Disregarding the fact that, in my 
 experiments, their walls arid their rather fluid contents never 
 exhibited a blue colour, the original presence of air in them may 
 be easily directly demonstrated. For if a stem held the wrong 
 end upwards is cut across and the wound immediately dipped 
 in a drop of thick solution of gum, there is no difficulty in seeing 
 bubbles of air emerge slowly from these tubes and inflate the dense 
 fluid, when the stem is squeezed from the root upwards toward 
 the wound. The ascent of bubbles of air begins directly, even 
 when the pressure is commenced six inches below the wound, 
 and it continues without interruption if the pressure is advanced 
 slowly upwards to the cut surface. To conclude from the wholly 
 accidental presence of water in these tubes, that they are nor- 
 mally conductors of liquid, is like deducing from the presence of 
 blood in the air- passages of a decapitated animal, that the lungs 
 are naturally intended for that fluid. While the smaller vessels 
 of the stem are usually spiral vessels, the structure of the larger 
 is very well worthy of notice, for their walls look as if formed of 
 small, nearly quadrangular frameworks, over which a delicate, 
 closely spotted membrane appears stretched. The petiole, like 
 the stem, is very rich in starch -bearing parenchyma; it is coated 
 by a rind, the partly elongated cells of which (but not the liber 
 cells) become deep blue ; the internal tissue exhibited very few 
 blue points, and the isolated spiral vessel bundles, in which air 
 was clearly seen under the microscope, bore no share in the 
 colouring. 
 
 Rhapisflabelliformis, Ait. (Palmaceae). The plant, a specimen 
 three feet high, was penetrated throughout all parts by the fluid 
 in ten days after watering. Stem : a transverse section, at least 
 in the upper part of the plant, displayed this enclosed in the 
 
14 HOFFMANN ON THE CIRCULATION 
 
 sheath of a leaf (like the scale of a bulb), which was especially 
 rich in sap and reacted strongly, while at the lower part of the 
 stem this part was already dead and in a great measure decayed 
 away. In this sheathing base of a leaf the elongated cells had 
 chiefly absorbed the salt, while the liber bundles were not dis- 
 coloured. The principal mass of the vessels (their walls present 
 short streaks) lie in some degree concentrically, at equal distances 
 from the centre and the circumference ; the vascular bundles, 
 with their woody envelopes, contained air and were not disco- 
 loured ; but in the rounded, four-sided, starchy parenchyma cells 
 between them, blue points were observed, which occurred in 
 proportionately largest quantity in the vicinity of the central 
 point and of the periphery. In a longitudinal section it was seen 
 that the reacting cells exhibited scattered points or little streaks, 
 and never lines continued in one plane. The vascular bundles 
 run pretty nearly parallel in the stem ; even the nodes exert no 
 influence upon the arrangement of the internal parts lying 
 opposite to them. When the stem was cut through higher up, 
 where it begins to lose itself in the leaves, a different appearance 
 was seen. Yet microscopical examination showed that here 
 again the salt had not ascended inside the vessels, but only in 
 their immediate neighbourhood, inside the elongated cells by 
 which they are accompanied. The upper leafy, as well as the 
 peripherical, parts of this plant reacted far more strongly than 
 the interior of the stem. 
 
 Commelina ccelestis, Willd. (Commelineas). This plant was 
 watered on the l?th of July; the examination was made on the 
 24th and 26th of July, and the 9th and 15th of August, but in 
 all cases the salt was sought in vain in the parts of the stem 
 situated between the nodes, while in the nodes themselves, from 
 the lowest to the uppermost, the reaction could be easily de- 
 tected. From this it appears, taking the other experiments into 
 account, that we must conclude the sap to rest for a time in 
 particular parts of plants, as in tubers, nodes, buds and ovaries, 
 while it hurries rapidly through others, especially the internodes 
 of the stem. The cross section of the nodes of the stem exhibits 
 a distinct separation into pith and rind. The bundles of spiral 
 vessels, which displayed bubbles of air in their interior when ex- 
 amined with the microscope, exist both in the pith and the 
 
OF SAP IN PLANTS. 15 
 
 cortical layer ; in the interne-dial parts of the stem the cortical 
 layer is contracted further inwards, so that there is not so sharp 
 a line of demarcation there. The points displaying the blue 
 reaction were among isolated roundish cells which occur inter- 
 nally and externally in the neighbourhood of the vascular 
 bundles. In longitudinal sections the blue points appeared in 
 an irregular band passing transversely through the node. In 
 buds examined four weeks after the watering (they had been 
 developed during this period),, blue colouring could be detected 
 inside the elongated cells of the calyx and the stigma, and inside 
 the minute parenchymatous cells of the (still white) petals and 
 of the connective, while the delicate spiral vessels, even in the 
 youngest, still imperfect organs, never displayed any colouring. 
 It is worthy of notice that the epidermis of the petals opposes 
 such a resistance to the penetration of the salt of iron, that no 
 reaction occurs even when the entire petal is dipped in sulphate 
 of iron ; hence it is necessary to tear the epidermis carefully 
 away to admit the sulphate of iron to the parenchyma when we 
 wish to bring out the reaction. 
 
 Commelina pubescens. The presence of the ferrocyanide could 
 be shown in the cells of the stem and leaves five days after the 
 watering. 
 
 Commelina clandestina, Mart. Here also the absorption could 
 be certainly demonstrated after a short period. 
 
 Commelina angustifolia, Michx. Detected certainly after 
 four days. 
 
 Commelina tuber osa. The absorption demonstrable in two 
 days, both inside longish cells and in isolated large cells of the 
 central parenchyma. 
 
 Gladiolus psittacinus, .Hook. (Iridaceae). Here again it was 
 easy to trace the salt many inches up the stem, and above all in 
 the elongated cells, in which it was very uniformly diffused, and 
 which are in part situated close to the air-bearing spiral and 
 annular vessels, and in part at a distance from these and near 
 the inner and outer epidermis of the separate leafy sheaths, of 
 which the stem is almost entirely composed. The inner and 
 softer leaf-sheaths of the stem reacted most strongly and conse- 
 quently appeared to convey the sap most actively. These plants 
 must contain a salt of peroxide of iron as a natural constituent, 
 
16 HOFFMANN ON THE CIRCULATION 
 
 for in four weeks after the watering, the leaves spontaneously 
 exhibited a deep blue colour at their tips. The plants all died 
 in little more than a month, apparently in consequence of the 
 watering with the ferrocyanide, since they were placed in con- 
 ditions otherwise favourable. 
 
 Tritonia fenestrata, Ker. (Iridaceae). Within two days after 
 the watering, the salt could be detected in the bulb and in the 
 lower part of the tuft of leaves. The lower part of the bulbous 
 mass (which is the bulb formed the year before, or real tuber) 
 was coloured very deep blue throughout ; in the upper bulb (of 
 the current year) it was observed that the parts giving a blue 
 reaction were little scattered points and streaks, which were 
 universally distributed. The microscope showed that those 
 lying in the central part were the elongated cells which sur- 
 round the air-bearing vascular bundles ; in the parenchymatous 
 part of the tuber the blue colour was deepest in the starch- 
 filled, irregular parenchymatous cells of which this structure is 
 composed. The circumstance that in all cases, and especially 
 distinctly here in the longitudinal section, the blue-coloured 
 cells were mostly scattered and only exceptionally formed unin- 
 terruptedly continuous lines, proves that the passage of the sap 
 does not take place uniformly through all parts indifferently, 
 but peculiarly through certain cells, which do not lie all in the 
 same place (parallel to the surface of the sections), but more or 
 less scattered, causing a ramification of the currents of sap often 
 of a very irregular character. 
 
 Allium neapolitanum, Cyr. (Liliaceae). Not even four weeks 
 after the watering could the presence of the ferrocyanide be de- 
 tected either in the interior of the bulb or in the stem. On 
 the other hand, the outermost dead scale of the bulb was 
 coloured of an uniform blue tint, evidently by accidental imbi- 
 bition of the fluid in contact with it, not only in the cells, but 
 both in the reticularly striped and the true unreliable spiral ves- 
 sels, which, moreover, still here and there displayed air in their 
 interior. 
 
 Canna indica (Canneae). This plant was growing in the open 
 air and was watered on the l?th of July. In seven days the 
 blue reaction could be readily detected in the stem. This exhibits 
 somewhat the same structure as the Palms in the cross section 
 
OF SAP IN PLANTS. 17 
 
 (vide Rhapis flabelliformis above), except that the vascular 
 bundles of the true axis are very irregularly scattered in the 
 interior, while they are arranged in a tolerably even radial order 
 towards the circumference. In the main axis itself the salt 
 could not be demonstrated with sufficient certainty at this time, 
 but with the greatest ease in the sheath (the base of a leaf) which 
 tirmly enveloped the whole main axis. Here the blue points 
 were found in greatest abundance close beneath the outer epi- 
 dermis, but also in large numbers immediately surrounding the 
 liber bundles (enclosing unreliable spiral vessels). The micro- 
 scope proved that the blue colour existed exclusively in uncom- 
 monly continuously stained cellules (containing large nuclei) 
 arranged in very straight longitudinal rows close beside the vas- 
 cular bundles. The arrangement of the spiral vessels, liber- 
 bundles and sap-conduits in the leaves was similar to that in 
 the stem. 
 
 Panicum plicatum, Lam. (Graminaceae). Had not absorbed 
 the least in four weeks ; the same happened in Ruscus aculeatus 
 and Ananassa sativa. 
 
 Arum divaricatum, L. (Aroideae). These plants had, for the 
 most part, absorbed nothing at all even after four months ; in 
 the few cases in which a weak reaction could be detected in the 
 tuber, the blue colour was found in the large parenchymatous 
 cells of the general substance, which contained the unusually 
 thick starch-granules, of beautiful pyramidal and polyhedral 
 forms with rounded faces ; while the scattered yellowish bundles 
 of partly round, partly angular annular vessels were never dis- 
 coloured. 
 
 Tradescantia discolor, L'Herit. (Commelinaceae). The reac- 
 tion was visible in the stem in four days after the watering. The 
 investigation is most difficult in the upper leafy parts, although 
 they are coloured deepest, because immediately the cortical 
 layer is cut across a great quantity of thick gummy liquid 
 exudes, which covers the whole surface of the section and con- 
 founds all the previously distinct fluids together. But when the 
 stem is cut lower down, a few inches from the ground, the in- 
 terior is found far less rich in sap, only a little mucilage exudes, 
 and it is more clearly seen when the absorption of the salt has 
 
 SCIEN. MEM. Nat. Hist. VOL. I. PART I. 2 
 
18 HOFFMANN ON THE CIRCULATION 
 
 occurred. A cross section at this point presents the following 
 appearance. At the outside a cortical layer, without vessels, 
 the starchy parenchyma of which is separated from the large 
 central parenchyma of the stem by a kind of liber-layer : the 
 central parenchyma, forming the great body of the stem, con- 
 tains scattered vessels divided into two sets, a central and a 
 peripherical, between which lies a ring of parenchyma free from 
 vessels. The cells which became blue lie in the vicinity of the 
 vascular bundles ; the gummy cortical layer was devoid of them. 
 It is worthy of notice that both the boundary between the liber 
 and parenchyma, properly the outermost layer of the central 
 cellular mass, and the immediate environs of the vessels scat- 
 tered in the central mass, emitted a small quantity of a tenacious 
 white sap, in which were suspended a few starch-granules and 
 an extraordinary quantity of minute raphides. No ferrocyanide 
 could be detected in the cortical layer even after the space of a 
 month. 
 
 Chlorophytum Sternbergianum, Steudl. (Liliaceae). In this 
 plant, which appears to derive the greatest part of the requisite 
 moisture from the atmosphere, it is difficult to diffuse a quantity 
 of the salt sufficient for the reaction in the ordinary way. The 
 slender filiform stem to which the tuft of leaves with their aerial 
 rhizomes and roots is attached, died in a few weeks, in conse- 
 quence of the watering, without much of the liquid having been 
 absorbed. In this case the cells of the bases of the leaves, as 
 also the aerial roots and the rhizomatous tubers, exhibited a 
 weak blue colour when cut surfaces were wetted with sulphate 
 of peroxide of iron. A clearer view may be obtained in a differ- 
 ent way. The aerial roots readily absorb fluids, for instance 
 water, when they are dipped into it ; moreover, sulphate of iron 
 was decomposed, the oxide fell as a yellow powder to the bot- 
 tom of the glass, while the water penetrated into the plant ; on 
 the other hand, a large aerial root which was already buried 
 in the earth and had taken root there, readily absorbed so much 
 ferrocyanide that this could be easily detected in longitudinal 
 and transverse sections several inches above the ground. The 
 central layer containing the dotted vascular bundles was found 
 free from colour ; but all the rest of the tissue, composed of 
 
OF SAP IX PLANTS. 19 
 
 elongated cells, even close in the vicinity of the former, had ab- 
 sorbed a considerable quantity of the salt, and exhibited innu- 
 merable blue dots and streaks in the longitudinal section. 
 
 Caladium viviparum, Roxb. (Aroideae). The fluid could be 
 detected in all parts of the tuber and petiole twelve days after 
 the watering. Minute examination showed the root to be a true 
 tuber, which in three weeks after the watering was found soft- 
 ened, collapsed, and, in short, dead (probably in consequence of 
 the watering) ; on reaction it turned uniformly blue all through, 
 just as a sponge would do under similar circumstances. On 
 this tuber is seated the bulb-like base of the stem, which en- 
 closes within it the true terminal bud of the axis. Both the 
 base of the stem and the central bud exhibited distinct reaction 
 in the same way ; in longitudinal and cross sections they became 
 covered with countless blue points, which were recognized under 
 the microscope as elongated cells. A leaf-bud which had just 
 been developed from the tuber had likewise absorbed the salt, 
 especially in its central region. The investigation is difficult in 
 the fully developed leaf-stalk, since this so abounds in sap, that 
 the fluid exuding when it is cut across readily spoils the expe- 
 riment with the reagent. The blue sap is found in the elon- 
 gated cells which surround the numerous round liber-bundles of 
 the thin peripherical or cortical layer, the latter enclose isolated 
 delicate unreliable spiral vessels*. The whole of the interior of 
 the leaf-stalk is composed of parenchymatous cells, inside which 
 run not only ordinary liber-like cells with vessels, but also 
 several canals, so large that a hair may be readily introduced 
 into them. These canals, still filled with fluid in the bud above 
 mentioned, contain air in the fully developed petiole ; when the 
 latter is squeezed even six inches from a cross-cut surface, air- 
 bubbles are forced out of them ; just as was described above of 
 the Dioscorea. The walls of these air-cavities are composed of 
 large cells; these tubes therefore form a transition to those of 
 Dioscorea, which exhibit a great affinity to the ordinary pitted 
 
 * The numerous thick- walled raphides-cells occurring here slowly expelled 
 their contents when accidentally injured, and these spread out like a tuft of 
 feathers, displaying a peculiar backward movement not unlike that of the 
 Oscillatoriese. 
 
 2* 
 
20 HOFFMANN ON THE CIRCULATION 
 
 wood-vessels. In the interior of the petiole the absorption of 
 the sap was indicated only by a few spots becoming blue. 
 
 Aloe picta, D.C. (Liliaceae). Not even after five weeks, any 
 more than at several shorter periods, could I detect the slightest 
 trace of the salt in the roots, buds, stem or leaves of these 
 plants, which were perfectly healthy, and which scarcely betrayed 
 any injury even at the point of the main root in consequence of the 
 watering. It is true the application of the salt of iron to a cross 
 section discoloured the yellow fluid (the aloe-bitter) which ex- 
 uded, transparent, from the large, very much elongated cells 
 near the spiral vessels at the whole periphery of the leaf, but the 
 stain was brownish black, not blue ; a reaction which occurred 
 also with Aloes of this species never watered with the ferro- 
 cyanide, and which therefore must be attributed to tannic acid. 
 The absence of absorption after the stated period is the less re- 
 markable, since these plants remain for seven months of every 
 year in a dry part of the conservatory, without ever being 
 watered, therefore without requiring any other fluid than that 
 which they receive through evaporation when other plants are 
 watered. 
 
 Zephyranthes grandiflora, Lindley ( Amaryllidaceae) . Three 
 days after the watering no reaction could be detected in the 
 bulb, petals, or ovules ; four days later, however, the bulbs ex- 
 hibited distinct blue spots both in their outer and also in their 
 inner scales, but the yellowish vascular bundles were not stained. 
 The different lamellae of the bulb consist here of two epidermal 
 surfaces, of parenchyma-cells full of starch, of elongated cells 
 which are very soft and loose, and especially contained the blue 
 fluid, and next to these, in the median line, of unreliable spiral 
 and annular vessels, surrounded by a few delicate prosenchy- 
 matous cells, as is usual in herbaceous plants. At this period 
 no salt had penetrated into the stem, not even into the lowest 
 part next the bulb. The plants in the same pot all died within 
 eleven days. 
 
 Cyperus monandrus, Roth (Cyperaceae). Nine days after the 
 watering the ferrocyanide was found in the stem and branches. 
 The rhizome, which was dug up after thirteen days, was, like 
 the whole plant, perfectly stiff and healthy, as was the case with 
 
OF SAP IN PLANTS. 21 
 
 almost all of the plants mentioned above, so far as the researches 
 here described go to show. The transverse section showed that 
 the salt had perfectly penetrated this, with the exception of the 
 yellowish vascular bundles which run in the thick parenchy- 
 matous cylinder ; otherwise a great quantity of dark blue cells 
 were found in all parts among the uniformly light blue mass of 
 cells. In the lower parts of the stem the reaction was only 
 weak ; it was more distinct in the peripherical part (no rind ex- 
 isted here) further up ; it was strongest at the apex, where the 
 separate flowering branches go off, for here not only the periphery 
 but also the interior of the stem was closely sown with blue 
 spots (streaks in the longitudinal section), which under the mi- 
 croscope were seen to be elongated cells : the angular, dotted, 
 and small streaked vessels which were situated partly near the 
 periphery and partly deep in the parenchyma of the stem, con- 
 tained air and had no share of the colouring. 
 
 * 
 
 III. DICOTYLEDONS. 
 
 In these plants we meet with a phaenomenon which is not 
 observed in those divisions of the vegetable kingdom above in- 
 vestigated, at all events not in Germany, namely, the " bleed- 
 ing, 55 or " tears/ 5 which occur on wounds of many of the shrubs 
 and trees of this division in early spring. 
 
 This phaenomenon is so peculiar that it will be advantageous 
 to examine it separately. In the following experiments I inves- 
 tigated, 1st, the course of the spring sap ; and 2ndly, that of the 
 summer sap, independently. 
 
 1. The Spring Sap. 
 
 1. On the 2?th of February 1850, a root A, of | an inch dia- 
 meter, coming from the west side of a white birch 6 inches in 
 diameter, was laid bare, cut across, and the upper cut end placed 
 in a cylindrical glass, of about 1 cubic inch capacity, filled with 
 a solution of ferrocyanide of potassium. This was done at four 
 o 5 clock in the afternoon. By the next morning the fluid was 
 absorbed as far as the root reached. 
 
 On the 27th also, several holes of 1 J line diameter were bored 
 ^ an inch deep, and into these introduced and cemented quills 
 
22 HOFFMANN ON THE CIRCULATION 
 
 of the same section, with the inner ends cut off obliquely and 
 the orifice looking upwards. These borings were made, 
 
 B, 3 feet above the ground, on the west side. 
 
 C, 3 feet above the ground, on the south side. 
 
 D, 5 feet high, on the south side. 
 
 On the 7th of March a clear fluid was first found in a vessel 
 attached below the quill (B), perhaps caused by rain which had 
 fallen on the 6th, and had run down from the stem. On the 
 8th of March the water (exuded from the stem) trickled from 
 B and C ; D remained dry. The fluid gave neutral reaction 
 with litmus paper. D did not become moist until the llth, 
 while B and C poured out abundance. The two last were closed 
 and cemented with resin on the 12th ; D was bored out 1 inch 
 deep, and a new hole was made of the same depth, 
 
 E, 2^ feet from the ground, on the south side. 
 
 The sap flowed immediately from both ; E delivered 70 drops 
 in five minutes, D only 15. On the 13th new traces flowed 
 from D; E gave 19 drops in five minutes. Both holes were 
 stopped and two new ones bored, 
 
 F, 6 feet high, north side. 
 
 G, 1 foot high, same side. 
 
 F gave only traces, while G gave 32 drops in five minutes. 
 On the 14th F gave nothing, G 10 drops in five minutes. On 
 the 15th F was dry ; G gave 45 drops in five minutes. On the 
 14th a new hole was bored, 
 
 I, 8 feet high, on the north side, which gave off no fluid on 
 the 14th or 15th. All these experiments were made at noon. 
 From the foregoing, the exudation and decurrence of the sap 
 occurred observably earlier in the lower than in the upper part 
 of the stem ; it was caused by a warmer temperature. 
 
 All these fluids were tested for the ferrocyanide with sulphate 
 or acetate of peroxide of iron, without results. It is evident 
 that none of the holes entered the current of sap passing up 
 from the root A (vide infra). On the 10th of March the 
 ascending root A was cut off and examined. The section 
 5 inches above the point where it dipped in the fluid, reacted 
 strongly with salt of iron and excess of hydrochloric acid, and the 
 same occurred with the other parts ; the ferrocyanide had even 
 descended into the lateral branches of the root. The longitu^ 
 
OF SAP IN PLANTS. 23 
 
 dinal section showed that the liber had absorbed strongly ; and 
 light blue, not sharply defined streaks, corresponding to the 
 course of the trachea?, were seen in all parts of the wood ; the 
 thin pith remained unaffected. On the whole the reaction was 
 weak, because the great mass of the fluid had already ascended 
 into the higher parts of the plant. 
 
 2. A young sycamore stem (Acer platanoides\ 3 inches in dia- 
 meter, was watered with the ferrocyanide in the ground ; but 
 this could not be detected in a small quantity of fluid which ex- 
 uded from boring. It appeared to have been wholly decomposed 
 by the (ferruginous) soil, since this had acquired a blue colour. 
 
 3. The soil at the base of a young sycamore of \^ inch dia- 
 meter was watered, on the 26th of February, with a weak solu- 
 tion of the ferrocyanide. On the 28th holes were bored into the 
 stem, but the drops which exuded did not react with salt of iron ; 
 neither did the of a drachm of fluid that was found on the 1st 
 of March. No more exuded after this. The soil around was 
 coloured blue, and when the stem was cut off on the 10th, no 
 ferrocyanide could be detected in it. 
 
 The small efflux of sap in these two young trees, 2 and 3, was 
 remarkable. 
 
 4. The earth round the trunk of a sycamore, 4 inches in dia- 
 meter and 35 feet high, was watered with solution of the ferro- 
 cyanide on the 2nd of March ; a hole, A, was then bored in the 
 stem 1 foot above the ground ; the vessel attached to this was 
 rapidly filled with fluid. Tolerable quantities of fluid flowed out, 
 and in part down, continuously during the following days, but 
 on the 7th of March no ferrocyanide could be discovered in it. 
 On this day the soil round the tree was watered a second time 
 with one ounce of a more concentrated solution ; the orifice con- 
 tinued to pour out freely. On the 9th the soil was watered a third 
 time, and a new hole was made (on the north side) at the same 
 height as the old one (on the south side). On the 10th of 
 March the fluid which had trickled from A gave a dark blue 
 precipitate with sulphate of iron, which was not the case with 
 B. On the llth no reaction on either side. On the 12th no 
 more had exuded ; on the 14th therefore the tree was cut off at 
 the base, and three pieces of it separated and examined, from 
 the base, the middle, and the summit. The two lowest pieces 
 
24 HOFFMANN ON THE CIRCULATION 
 
 only gave a reaction, which was moreover very weak ; the trans- 
 verse section displayed a few light blue bleared spots in the 
 wood ; the liber and bark were unaffected. Longitudinal sections, 
 on the contrary, displayed at particular spots, very sparingly, 
 sharply denned blue points or even streaks (some of them in 
 the direction of the medullary rays) ; microscopic examination 
 showed that the few places in which some of the absorbed sap 
 still remained, were tracheae (spiroids) and the neighbouring 
 prosenchyma of the wood. In the middle fragment, 10 feet 
 above the ground, the cross section gave the same result as 
 before; longitudinal sections led to none. 
 
 5. On a young sycamore, with a trunk 4^ inches in diameter, 
 a branch A, arising 7 feet above the ground on the north side, was 
 bent down to a certain degree and fixed in this position, the 
 outer part cut off, and the point of the portion remaining attached 
 to the stem, dipped 4 inches deep into a cylindrical glass full of 
 solution of the ferrocyanide. A hole B was bored, 1 inch deep, 
 1 foot above the ground on the south side of the trunk. This 
 was done on the 2nd of March. On the 3rd the branch A 
 had absorbed all the fluid, as far as it dipped in it ; the glass 
 attached under B was filled with watery fluid, which did not 
 react with salt of iron. On the 5th the glass at A was refilled. 
 On the 4th the vessel at B was only half-filled; on the 5th 
 again quite filled ; rain which fell on the 4th seemed to have 
 increased the flow of the sap. By the 7th (warmer weather 
 than the 6th) the glass A had been again emptied, and was filled 
 anew. On the 9th again empty, but up to this day, when the 
 efflux at B ceased, no ferrocyanide could ever be detected in 
 the fluid poured out. On this day therefore a new hole C was 
 bored at the same height as B, on the north side of the trunk, 
 corresponding to the absorbing branch A ; and in spite of B 
 having stopped, fluid was poured out freely at C, which on the 
 10th reacted deep blue with the iron salt; the glass A was 
 emptied down to a quarter of its contents (it held altogether 
 about 1 cubic inch). On the llth the freshly effused fluid ex- 
 hibited a very strong reaction. 
 
 The here evidently strong suction of a cut branch, or of a cut 
 root, as in Experiment 1, thus both in the ascending and de- 
 scending directions) results from the pressure of the atmosphere. 
 
OF SAP IN PLANTS. 25 
 
 The large surface of the tree with its hundreds of shoots causes an 
 evaporation even before the buds swell ; the vacuum resulting 
 from this, causes any fluid which may be brought into free com- 
 munication with the interior of the tree, at any spot, to be driven 
 in by the vis a tergo. The power of suction thus produced 
 increases in equal proportion as the surface of the shoots is in- 
 creased by the presence of leaves, and the capacity of the air to 
 retain moisture by the heat of summer, as Hales (Vegetable 
 Statics) and, more recently, Dassen (Wiegmann r s Archiv, xiii. 
 2. p. 311) have proved; under the most favourable circum- 
 stances it sustains a column of mercury 12 inches high. Itw 7 ill 
 not be thought strange that the height of the column of mercury 
 did not attain 18 inches, as has been observed in curved glass 
 tubes under similar circumstances. The bark of the shoots of 
 a tree does not form a solid envelope like the glass, for even with 
 a smaller weight of the column of mercury, the air itself pene- 
 trates through the bark into the interior, and thus puts an end 
 to all further ascent. Hence the loose-barked vine absorbs but 
 weakly ; the denser Prunus domestica raised a column to ^th of a 
 Flemish ell (6J- inches) ; Betula nana, 0'240 (13| inches) (Das- 
 sen). Hales observed the column rise to 4 inches in the vine, 
 and 12 inches on an apple branch (equal to 13 feet 8 inches of 
 water) . 
 
 Tt is remarkable how accurately the fluids ascending or de- 
 scending in this way are retained in that side of the stem which 
 corresponds to the absorbing branch (or root) ; this is explicable 
 by the straight, uninterrupted, little-branched course of the 
 tracheae ; the anatomical examination of the preceding cases also 
 proved this directly. The absorbing branch was cut off on the 
 llth of March and anatomized, with the following results. In a 
 cross section 1 line above the lower end, which had been dipped in 
 the fluid, all parts, bark, liber, wood and pith, reacted deep blue ; 
 but even at a distance of 2 lines the pith was found uncoloured ! 
 Four inches further up, that is, close above the upper boundary 
 of that portion of the branch w r hich had been immersed in the 
 fluid, the heart-wood in the vicinity of the pith was also found 
 uncoloured, as was the case everywhere above this. From this 
 point the pitted and striped trachece of the softer external por- 
 tion of the wood, with the liber, had taken on the conduction of 
 
26 HOFFMANN ON THE CIRCULATION 
 
 the fluid, and on reaction formed sharply defined dark blue 
 lines, which could be easily traced even in the stem, both up- 
 wards and downwards, more than 1 foot from the absorbing 
 branch. Microscopic investigation showed that the blue colour 
 had only spread half or the whole width of a row of cells, around 
 the trachea3. A longitudinal section of the (upper) axil of the 
 branch indicated the course of the trachea by curvilinearly ar- 
 ranged blue spots and streaks, and not by continuous blue lines. 
 Consequently these tracheae do not run so perfectly on one and 
 the same plane here, that their entire course can be at once dis- 
 played by a single section. It is worth notice, that only that 
 side of the stem on which the branch was seated was coloured 
 blue, the opposite not at all. 
 
 That the pith does not conduct, is comprehensible, since the 
 air it contains could not readily be displaced by water pene- 
 trating, and each of these cells containing air is a completely 
 closed sac. But it is difficult to understand why the medul- 
 lary sheath and the heart-wood do not conduct sap, since here 
 communicating unreliable spiral and striped tracheae are present 
 in abundance. This non-conducting layer amounted, at the 
 point of attachment of the branch, to a quarter of the woody 
 layer (the entire diameter of the stem at this point amounted to 
 ! inch). It is certain that the air visibly contained in these 
 trachea3 is no hindrance, for it is none in those of the outer, 
 younger wood. The elongated cells of the medullary sheath 
 are far narrower and closer than the prosenchymatous cells of 
 the wood; they are crowded with starch- granules, which are 
 absent from the rest of the prosenchyma of the wood up to the 
 medullary rays. Can it be some starchy or gummy mucilage 
 which stops the progress of the fluid ? I believe not ; there is no 
 dissolved starch present ; iodine distinctly reveals the unaltered 
 starch-granules. And as to gum, it is not evident how this 
 could close up the trachea from the cells, since the microscope 
 shows the former to be filled with air-bubbles. 
 
 6. Repetition of the preceding experiment. On a sycamore 
 trunk 3 inches in diameter, a branch A, at a height of 5 feet, 
 was cut off, bent down, and fastened : the wound dipped in a 
 glass of 1 cubic inch capacity, filled with concentrated solution 
 of ferrocyanide of potassium. At the side (the south) of the 
 
OF SAP IN PLANTS. 2? 
 
 trunk a hole B was bored at 1 foot above the ground, and a 
 glass attached to catch the exuding fluid. On the following 
 day (March the 5th) the vessel at A was almost empty and was 
 refilled. In the glass at B there was no fluid ; but on March 
 the 6th |th of a cubic inch, which reacted deep blue with sulphate 
 of iron. On the 6th the glass A was only half empty, but was 
 refilled. On March the 7th, at 2 o'clock P.M. (as usual), A was 
 half empty ; nothing had flowed from B, but the orifice reacted 
 deep blue with salt of iron. A new hole C was bored ^rd of a 
 foot above the ground, on the east side, but no fluid exuded. 
 On the 8th of March A was half empty ; nothing had flowed 
 from C. On March 9th A was quite empty ; C had given off 
 nothing. 
 
 The tree was cut down on the 9th of March in order to trace 
 the course by which the fluid had descended from the absorbing 
 branch to the orifice. The liber and albumen reacted blue, but 
 not the bark, heart-wood or pith. In the albumen the colouring 
 was streaky, and the microscope showed that it was in the 
 tracheae : these contained blue fluid with a few air-bubbles. 
 The liber was not coloured nearly so far as the woody portion ; 
 at 3 feet down the stem from the absorbing branch (on the same 
 side), the wood reacted very distinctly, but not the liber. From 
 this it follows that capacity of conducting is much inferior in the 
 liber-layer, to what it is in the tracheae of the wood. Distinct 
 reaction in blue streaks could also be observed in the trunk 
 more than 2 feet above the branch, on the same side (but not 
 on the other) ; here the liber was affected, although not so 
 strongly. A transverse section showed that about rd of the 
 circumference of the trunk below the branch, ^th above it, had 
 taken part in the diffusion of the sap : the base of the branch 
 occupied about J-th of the circumference. Dissection of the point 
 of insertion of the branch on the stem gave exactly the same 
 results as in No. 5. Examination of the wood in the vicinity of 
 the orifice, and 2 inches lower down by radial longitudinal sec- 
 tions, showed that the trachea, had conveyed down the solution : 
 the cellular tissue and medullary rays did not react. 
 
 It is evident, therefore, that both in normal absorption by 
 uninjured roots, and in abnormal by wounds, the conduction of 
 the spring sap occurs chiefly through the trachea and liber ; a 
 
28 HOFFMANN ON THE CIRCULATION 
 
 result which stands in contradiction with the experiments already 
 related on Monocotyledons and Acotyledons at the time of the 
 full activity of the leaves (vide infra). 
 
 Comparison of the Experiments 5 and 6 with 4, shows how- 
 much more quickly the fluid runs through the tissues when it is 
 placed in contact w r ith open wounds, than when the absorption 
 is allowed to take place in the normal way by the root. In 5 
 and 6 the ferrocyanide traversed some 8 feet, down from the 
 cut branch to the orifice, in one day; in 4 it occupied seven days 
 for the salt with which the soil (root) was watered to ascend to 
 an orifice 1 foot above the ground. In the former there were 
 open communicating tubes, in the latter closed membranes only 
 permeable through endosmose. 
 
 7. In a young sycamore of about 3 inches diameter, a root on 
 the west side, A, an inch in diameter, was laid bare, cut through 
 at the distance of a foot from the trunk, and the upper end 
 placed in a cylindrical glass of 1 cubic inch capacity, containing 
 solution of ferrocyanide. An orifice B was made at a height of 
 
 1 foot above the soil, on the south side of the trunk, and a glass 
 vessel fixed under the quill introduced into it. On the following- 
 day (March 5th) the vessel at A was found empty, and was 
 refilled ; B w r as half full of fluid (^ a cubic inch). On March 
 6th, A, again empty, was again refilled ; B contained ^rd of a 
 cubic inch of fluid. On the 7th, A as the day before ; nothing 
 emitted from B. On the 9th, A empty. On the 10th, A was 
 refilled ; B contained fluid again (J a cubic inch), evidently in 
 consequence of warm weather the day before. None of the 
 exuded fluid gave reaction with salt of iron. On the llth, 
 nothing emitted from B. A new hole C was bored on the west 
 side, corresponding to the root A, 6 inches above the ground, 
 but nothing flowed from it up to the 13th. Although, there- 
 fore, the fluid had been absorbed, it was impossible this time to 
 draw it from the stem here by tapping ; evidently because the 
 orifice B, which alone emitted fluid, was not made on the cor- 
 responding side of the stem. The observations were made at 
 
 2 P.M. each day. 
 
 On the 13th of March the absorbing root was cut off and 
 dissected. Reaction with sulphate of iron and hydrochloric acid 
 showed that the exceedingly small pith had not conducted. At 
 
OF SAP IN PLANTS. 29 
 
 a distance of about 10 inches from the immersed lower end (the 
 root dipped in about 3 inches), the longitudinal section gave a 
 blue reaction throughout the woody substance ; the microscope 
 showed liber, tracheae and wood-cells stained ; the tracheae most 
 strongly, both in the inner and outer parts of the wood. The 
 solution had not only ascended, but also passed down as much 
 as 2 inches in small lateral branches of this root. At these points 
 the liber no longer took part in the conveyance of the fluid, 
 while many (especially the central) tracheae reacted deep blue. 
 
 It is worth notice that the (ferruginous) soil in the vicinity of 
 the entire root acquired a blue colour from the 6th of March 
 onward ; perhaps by secretion through the peripherical parts of 
 the root, perhaps through the injured points of the little radical 
 fibres. 
 
 8. A sycamore trunk of f of a foot diameter was bored with 
 similar holes, 1 inch deep, in two places, and all the exuding 
 fluid was caught. 
 
 A, orifice 1 foot from the ground, south side. 
 
 B, orifice 3 feet from the ground, south side, 1 inch further 
 westward. 
 
 Experiment commenced at 3 o'clock on the 5th of March. 
 
 Five o'clock : A had emitted 1 Paris cubic inch of clear watery 
 fluid; B i a cubic inch. 
 
 March 6th, 8 A.M.: A and B had secreted nothing (cold night, 
 below freezing point). 
 
 2 30 P.M. : A 9 cubic inches; B 12 cubic inches. 
 
 5 30 P.M. : A and B had each given off^th of a cubic inch. 
 
 March 7th, 8 A.M. : the flask at A and B empty. 
 
 2 P.M. : A f ths of a cubic inch ; B J-th of a cubic inch. 
 
 5 30 P.M. : the flasks at A and B empty. 
 
 March 8th, the same. 
 
 According to the foregoing, night limits the force of the cur- 
 rent (by a lower temperature). When we reflect on the unequal 
 duration of the bleeding in the trees 2 8, which all stood near 
 together, it becomes a question what was the cause of this 
 phaenomenon ? 
 
 The varying thickness of the trunk does not seem to explain 
 the matter. No. 4 was 4 inches in diameter and bled ten days ; 
 No. 2 was 3 inches in diameter and bled five days ; No. 8 was 
 
30 HOFFMANN ON THE CIRCULATION 
 
 9 inches in diameter and bled only three days. Neither does 
 the height of the orifice above the soil explain the phsenomenon, 
 for the period of bleeding differed much at equal heights, as 
 No. 8 and No. 4 show. Just as little influence is exerted by the 
 aspect of exposure. 
 
 On the other hand, the higher or lower position of the trees 
 appeared to have an essential influence hydrostatically , They 
 all stood on the southern slope of a hill 30 feet high, in the 
 Botanic Garden at Giessen, in the following order, from above 
 downwards : 
 
 a, No. 8, which bled 3 days. 
 
 b, - 2, .... 5 . . 
 
 c, 5, .... 5+3 days. 
 
 6, 4 . . 
 
 4-3, .... 2 . . 
 
 7, .... 7 . 
 e, - 4, .... 10 .. 
 
 No. 4 stood 5 feet above the bottom of the hill, and was 
 35 feet high; the rest were only about 27 feet, in spite of their 
 unequal diameter. This difference of height also appeared to 
 have some influence. 
 
 The epochs of tapping the different trunks were not far enough 
 apart for me to ascribe any considerable importance to that point. 
 
 9. A trunk of Acer campestre, 1| foot in diameter (at the 
 bottom), was tapped at equal depths of 1 inch, in two places, at 
 3 o'clock on the 5th of March, and the exuding fluid all collected 
 (as in all cases, with care that no rain-water should penetrate) : 
 
 A, orifice 1 foot from the ground, south side. 
 
 B, the same, north side. 
 
 By about 5 o'clock A had delivered Ifths of a cubic inch, B 
 also Ifths. 
 
 From that time till 8 A.M. on the 6th of March not a drop 
 flowed out. About 2 o'clock there were 13f ths cubic inches in 
 A, and 19J cubic inches in B. At 5 h 30 m there was J a cubic 
 inch from each. On the 7th at 8 o'clock there was no fluid. 
 At 2 o'clock there was ^th of a cubic inch at A, ^ a cubic inch at B. 
 At 4 o'clock no more had flowed out ; neither was there any at 
 2 o'clock on the 8th. From the little that the short duration of 
 the bleeding allowed to be observed here, the north side would 
 
OF SAP IN PLANTS. 31 
 
 appear to pour out more sap than the south. The checking 
 influence of nocturnal cold was again distinctly visible here. 
 
 10. On the 10th of March a young sycamore stem (Acer 
 platanoides), 3 feet high and \ an inch in diameter, was plenti- 
 fully watered with solution of ferrocyanide of potassium. On 
 the 15th it was taken up, root and all. When dissected, the 
 reagents showed that absorption had not commenced in the 
 stem. At the base alone, weak, bleared blue spots were pro- 
 duced on a cross section. In one place the colour was deep and 
 sharply-defined enough to admit of microscopic examination : 
 this proved that the walls of a few streaked and spotted tracheae 
 were coloured blue. 
 
 11. A white birch, with a trunk 1 foot in diameter, was 
 tapped 1 foot above the ground, on the west side, on the 4th of 
 March ; up to the llth nothing flowed out. On this day a new 
 orifice was made in the west side of the stem, at a height of 
 7 feet. Up to the 14th neither gave off any liquid. Only a few 
 sucking flies appeared to indicate that the sap was beginning to 
 rise. 
 
 It is worthy of notice, how much later the bleeding occurs in 
 the birch than in the sycamore. 
 
 12. On the 7th of March, at three o'clock, a sugar maple 
 (Acer saccharinum), with a trunk 1^ foot in diameter, was 
 tapped : 
 
 A, orifice 1 foot from the ground, south side. 
 
 B, orifice 5 feet from the ground, south side, but 1 inch 
 further to the east. 
 
 About eight days previously several small branches had been 
 cut off further up the stem; some sap ran down from the 
 wounds. The fluid exuding from the borings was collected, 
 and gave the following results : 
 
 March 7. 3 o'clock, at A, 3 cub. in. ; at B, 1 cub* in. 
 
 - .- 5J .... 3* 7i .... 
 
 8. 8 
 
 . . 2 
 
 .. 5 ... 
 
 9. 7 
 
 .. 2| ... 
 
 - .. 5* 
 
 8| ;;;; :.'.': 
 11 
 
 a few drops. 
 4 cub. in. 
 4 
 
 17 
 
 none. 
 7f cub. in. 
 
38(1) .... 
 9 
 
 11 
 . . 4 
 
 13* .... 
 9 
 
 i 
 
 4 
 
 14 
 
 
 3 
 
 4 
 
 4 
 i 
 
 17 
 
 34- 
 
 4* .... 
 6* .... 
 15i 
 
 .... afi 
 1 c 
 
 32 HOFFMANN ON THE CIRCULATION 
 
 March 10. 7 o'clock, at A, 3 cub. in. ; at B, 1 cub. in. 
 
 - .. H ... 
 
 .. 5 
 
 11. 7 
 
 ..2 
 
 - .5* 
 
 12. 7 
 
 ..2 
 
 ..5 
 
 13. 7i 
 
 . . 2 
 
 . . 5* .... 4^ a few drops. 
 
 14. 7i .... 13| ditto. 
 
 ..2 .... 23 . . 2| cub. in. 
 
 . . 5 .... 1 none. 
 
 15. 7% ... none none. 
 
 ..11 .... 5 i cub. in. 
 
 From this it follows that the efflux, or fulness of sap, is greater 
 in the lower part of the stem than further upwards. This 
 phenomenon is not hydrostatical (as a barrel emits a more pow- 
 erful stream from a hole nearer the bottom, than from one at the 
 top, on account of the higher pressure of water), but depends 
 on the force of the water making its way upwards, as is seen by 
 a comparison with Experiment No. 1. It is also again seen 
 what an obstacle the nightly cold is. Lastly, a comparison of 
 the temperatures of the air in the sun, which I observed, shows 
 how much the ascent of the sap is favoured by the heat of the 
 air. 
 
 From the following table, especially from the two last columns, 
 it is seen that on the whole the outflow runs parallel with the 
 temperature. The 10th of March alone forms an exception, evi- 
 dently on account of the unusually favourable weather on the 
 9th, the after-influence of which is seen here. 
 
OF SAP IN PLANTS. 
 
 SCIEN. MEM. Nat. Hist. VOL. I. PART I. 
 
34 
 
 HOFFMANN ON THE CIRCULATION 
 
 The specific gravities of the effused fluid exhibited the fol- 
 lowing scale. They were determined in a narrow-neck globular 
 bottle, of about 1 oz. capacity. 
 
 Rain water, 1st filling . . . 25 '660 grammes. 
 
 2nd 25-661 
 
 3rd . 25-665 
 
 Sap of the Sugar Maple. 
 
 March 7. 3i o'clock 
 
 8. 4 .... 
 
 9. 2| 
 
 10. 2 .... 
 
 11. 2 
 
 12. 2 .... 
 
 13. 2 .... 
 
 14. 2 
 
 Orifice A. 
 
 25 '877 gramm. 
 25-875 .... 
 25-871 .... 
 25-861 .... 
 
 25-889 
 
 25-883 .... 
 
 25-890 
 
 25-896 
 
 Orifice B. 
 25-918 gramm. 
 
 25-918 
 
 According to this, the specific gravity increases pretty rapidly, 
 and the sweetness of the sap also is readily detected by the 
 tongue. The upper part of the stem contains a less aqueous sap 
 than that near the soil. 
 
 The reaction of the exuded fluid was neutral to blue litmus 
 and to turmeric paper in a fresh condition on the 8th of March ; 
 on the 9th slightly acid, as also on the 15th. 
 
 The amount of sugar contained was tested by adding solution 
 of potash, a few drops of solution of sulphate of copper, and 
 boiling; after a long- continued boiling only was a very small 
 quantity of copper reduced. Some ammonia was set free in 
 this operation. When the mixture was merely allowed to stand 
 at ordinary temperatures, not the least copper was reduced in 
 two hours. It was therefore cane-sugar. 
 
 13. A birch (Betula pubescens, Ehrh.) was tapped in two 
 places at half-past two o'clock on the 8th of March. The base 
 of the trunk was 1 J foot in diameter. 
 
 A, orifice 1 foot from the ground. 
 
 B, ... 7 feet 
 
 Both orifices 1 inch deep. Quills were cemented in and the 
 effused fluids caught. On the upper part of this birch a few 
 small branches had been cut off, from which some sap exuded, 
 which, however, did not run down to the bottom. The following 
 quantities flowed out : 
 
OF SAP IN PLANTS. 35 
 
 March 8. Up to 4 o'clock at A, 9* cub. in. ; at B, 7 cub. in. 
 
 . . 5* .... 7 4 
 
 9. ..7* .... 391 8* .. 
 
 . . . . 2* .... 23| ? 
 
 . . . . 5* .... 9 6 
 
 - 10. . . 7* .... 5f- If . . 
 
 -. -. 2 .... 18* 15* .. 
 
 . . . . 5 .... 7 .... 121 .. 
 
 11. .. 7 .... 13* 4* .. 
 
 .- 2* .... 9* If V. 
 
 - .. .- 5* .... 3* 6* .. 
 
 12. .. 7* .... 5| 7* .. 
 
 . . . . 2 .... 19f 38 
 
 As there was no fixed result here, the holes A and B were 
 bored out again to remove any accidental obstruction. 
 
 March 12. Up to 5 o'clock at A, 5 cub. in. ; at B, 9 cub. in. 
 
 13. .. 7i .... 9J 31* .. 
 
 . . . . 2 .... 4f 33 . . 
 
 .. 5* .... 2 12 .. 
 
 14. . 7| .... 6* 39*.. 
 
 . . . . 2 3 39*.. 
 
 A was closed up, and a new hole C bored near it. 
 
 March 14. Up to 5* o'clock, from C, 5 cub. in. ; fromB, l^cub. in. 
 
 15. .. 7* | .. none. 
 
 ..11 3 . . 4 drops. 
 
 Thus, from the 8th to the llth of March more flowed from 
 below; from that time the proportion was reversed, perhaps 
 in consequence of the more powerful swelling of the lower 
 (wetter) wood at A, and a contraction of the orifice resulting 
 from this. After a new hole was bored, the proportion was as 
 in ordinary cases (compare Experiments 20 and 21). 
 
 The specific gravities of the fluids from A, B, and C, exhi- 
 bited the following scale : 
 
 March 8. Spec. grav. of A, 25*705 gramm. ; of B, 25715 
 
 9 25-690 .... 
 
 10. .. 25-712 
 
 11 25-728 .... 
 
 12 25-722 .... 
 
 13. .. 25-718 25717 
 
 14. .. 25-714 25-719 
 
 15. Spec. grav. of C, 25*732 .... 
 
 3* 
 
36 HOFFMANN ON THE CIRCULATION 
 
 According to this, there was increase at A from the 9th to 
 the llth, then from the 12th (through a fall of snow on the 
 llth) decrease; on the 15th increase (through the preceding 
 warmth, and resulting evaporation of moisture from the earth ?) ; 
 at B increase. The sap from the lower orifice was not so dense 
 as that from the upper. 
 
 The reaction of the fresh sap was neutral to blue litmus and 
 turmeric papers on the 8th and 9th of March; on the 15th 
 slightly acid. 
 
 On the 8th and on the 15th the taste was indistinctly sweetish 
 and earthy ; but chemical testing demonstrated the presence of 
 grape- sugar, when the fluid was warmed with solution of pot- 
 ash and sulphate of copper, since a red powder was rapidly 
 thrown down. 
 
 14. A birch (Betula pubescens, Ehrh.) 1 foot in diameter was 
 tapped in various places, in order to discover whether more fluid 
 was effused from the upper or lower part of the stem. This 
 took place on the 14th of March, at three o'clock. 
 
 A, East side, 1^ foot high, gave in 5 minutes 335 drops. 
 
 B, 8 feet .... 120 . . 
 
 A and B were then closed. 
 
 C, North side, 2 feet high, gave in 5 minutes 118 drops. 
 
 D, ..,- 8 . . .... 80 .. 
 
 The lower orifice therefore gave more than the upper. 
 The fluids of A and B were neutral with test-papers. 
 
 15. Repetition of the preceding experiment in another birch 
 of the same species and of the same size. Experiment made 
 after three o'clock on the 14th of March. 
 
 A, N.E. side, 1 foot from the ground, gave in 5 minutes 93 drops. 
 
 B, 9 feet 103 .. 
 
 A and B were closed, and two new holes bored. 
 
 C, North side, 1 foot from the ground, gave in 5 minutes 63 drops. 
 
 D, .. 9 feet .... .... 51 .. 
 
 Here also the lower orifice usually emitted more than the upper. 
 The striking and frequent anomalies which appeared here, as in 
 Experiment 13, will appear abundantly explicable when we 
 reflect what an important influence a very small difference in 
 the condition of the orifices (in regard to depth, diameter, quan- 
 
OF SAP IN PLANTS. 37 
 
 tity of fragments of wood remaining in, &c.) and the unequal 
 expansion of the wood must have ; a difficulty which I could 
 not master. Here, therefore, useful results could only be ob- 
 tained by a number of observations. 
 
 II. THE SUMMER SAP. 
 
 The circulation of the sap during the summer, at the period of 
 the greatest activity of the leaves, displays at once much agree- 
 ment with and many striking differences from that of the early 
 spring, among the latter of which stands above all the circum- 
 stance that the trees hitherto mentioned no longer bleed from 
 wounds inflicted on them, although, as a little reflection must 
 reveal, the quantity of fluid actually passing in the stem is far 
 greater; a fact also demonstrated by direct observation. 
 
 In summer, as in spring, there exists a rapid ascent of the 
 crude sap ; in addition to this, a descent of unelaborated fluids 
 after every shower of rain ; and, lastly, a descent of the elabo- 
 rated fluids from the leaves into all parts of the plant. 
 
 Since there apparently exists no means of tracing accurately 
 the mode and course of the last phenomenon directly, I have 
 restricted myself to the first, namely to the roads which the un- 
 elaborated fluids traverse in their ascent and descent in plants ; 
 but the results obtained could not but give ground for the de- 
 duction of many conclusions as to the behaviour of the elabo- 
 rated saps. The following pages therefore will be devoted to the 
 investigation of the paths by which the crude summer sap 
 ascends or runs down under conditions as natural as possible, and 
 afterwards also under various abnormally arranged conditions, 
 especially when wounds have been made in the plant. 
 
 A. THE ASCENDING SAP. 
 1. With NORMAL, absorption of the Sap by the Root. 
 
 For the purpose of tracing the course of the sap, the earth 
 round the plants to be experimented on was watered with dilute 
 solution of ferrocyanide of potassium ; after which cross slices of 
 the plant were tested for that solution with a mixture of acetate 
 of iron and hydrochloric acid. It is not advisable to make these 
 experiments on plants standing in the open ground, since the 
 
38 HOFFMANN ON THE CIRCULATION 
 
 fluid is here spread about too much and too unequally ; hence 
 the absorption becomes very uncertain, or even fails to take 
 place at all, as I have experienced several times to my dis- 
 comfort in vines, plums, and sycamore trees. I therefore pre- 
 ferred such plants as had been kept a longish time in pots, 
 taking only such as exhibited a full activity of vegetation. 
 
 Euphorbia terracing L. Watered on the 5th of June ; taken 
 up by the root on the 8th. The saline solution was detected in 
 the inner layer of the bark (the liber), and in a few tracheae or 
 spiroids of the outer layer of wood. Watered on the 15th; 
 withering on the 24th ; taken up on the 25th ; the saline solu- 
 tion could be detected last, as far as 2| inches above the collar of 
 the root, in the striped spiroids of the outer layer of wood and 
 in the liber, in which it ascended farthest. These vessels were 
 only partially filled with the saline solution ; the majority still 
 contained air and did not react. 
 
 Since in these and several similar cases, not only the cellular 
 tissue, but also in direct opposition to the preceding observa- 
 tions on the Monocotyledons the air-vessels took part more or 
 less in the conduction of the sap, the first object was to clear up 
 the contradiction. 
 
 The Monocotyledons used in my investigations, whatever 
 their other differences, were almost without exception furnished 
 with tuberous or bulbous rhizomes. The conjecture was not 
 far-fetched, that the predominant subterraneous stem-structure, 
 the whole character of w 7 hich is, moreover, accumulative and 
 retentive, retarded the conveyance of the fluid into the upper 
 portions of the stem, and thereby exerted essential influence 
 over it. Hence arose the question, whether, in the Dicoty- 
 ledons also, varied conditions in the conduction of the sap 
 would occur according to the rapidity of the absorption, accord- 
 ing to superabundant or scanty watering, &c. 
 
 a. Accelerated absorption of the Fluid. 
 
 Balsamina hortensis. The root was carefully freed from earth 
 and immersed in a large vessel full of solution of the ferrocy- 
 anide ; then the stem was cut across obliquely at a height of 
 8 inches, and sucked with the mouth. After the sucking had 
 been continued for half an hour, reaction occurred at this point ; 
 
OF SAP IN PLANTS. 
 
 the solution had penetrated into several of the large and small 
 spiral vessels of the stem, and still more had ascended in the 
 delicate parenchymatous tissue surrounding the vascular bun- 
 dles ; the pith and remaining portions of the cellular tissue had 
 taken no part. When the lower end of a fragment of a balsam 
 stem 3 inches long was dipped in ink and the upper end sucked, 
 the ink rose instantaneously. From this is evident how consi- 
 derable an obstacle the uninjured epithelium of the root opposed 
 to the forced penetration of the fluid in the preceding case. 
 
 Bahamina hortensis. The plant was allowed to stand dry 
 from the 14th to the 19th of June, until the withering stem had 
 collapsed considerably. The soil was then well watered with 
 14 cubic inches of dilute solution of the ferrocyanide, which was 
 wholly retained by the mould, as in a sponge (the plant stood 
 in a pot 5 inches high and 4 inches in diameter). On the 21st 
 it began to wither, the leaves exhibited spots and died, while 
 the stem was still partly elastic. On the 23rd the plant was 
 analysed. All parts had absorbed. In the cellular tissue of the 
 pith and rind, the intercellular spaces or passages, especially, 
 were found deep blue, so that the rind-cells which contained a 
 red sap, presented red spots enclosed in blue frames; in the 
 pith the whole of the cell-contents were coloured blue in many 
 places. The vessels, striped as well as unreliable spirals, to- 
 gether with the immediately adjacent prosenchyma, were almost 
 without exception dyed deep blue ; air-bubbles were met with in 
 very few, but sometimes even in those vessels which contained 
 blue fluid. 
 
 b. Retarded absorption of the Fluid. 
 
 Ox alls tetraphylla. Watered very slightly with the saline 
 solution from June 25th to July 2 7th ; the plant was exposed to 
 the atmospheric moisture in the open air. About this time the 
 leaves began to lose their colour and wither. Analysis. The 
 bulb is composed of two distinctly separated circles of scales, 
 from the interior of which springs the leaf-stalk. The solution 
 was principally met with in the periphery of the inner portion 
 of the bulb ; and the elongated cells at the surface of the separate 
 fleshy scales, but not the spiroids, had also absorbed it in very 
 small quantity. Leaf-stalk. This contained a loose circle of 
 
40 HOFFMANN ON THE CIRCULATION 
 
 five vascular bundles ; the salt had ascended in the prosenchy- 
 matous cellular tissue surrounding these, but not in the tracheae 
 themselves ; the latter were filled with air. The cortical layer 
 had also conducted, and indeed in the intercellular passages. 
 
 Euphorbia terracina, L. Treatment as in the preceding case : 
 taken up at the end of four weeks. The solution had ascended 
 in small quantity, especially in the inner cortical layer, the liber. 
 No saline solution in the vessels of the wood. 
 
 Hibiscus Trionum. Watered with 1 cubic inch of the saline 
 solution during heavy rain ; taken up after three days. Only the 
 root had absorbed up to this time, and chiefly in the central 
 layer of wood, where the prosenchymatous cells in the vicinity 
 of the vessels were coloured blue in spots : the tracheae took no 
 part. 
 
 These experiments showed that when small quantities of liquid 
 are absorbed by the root, the sap of herbaceous Dicotyledons 
 ascends, just as in the Monocotyledons above described, in the 
 cellular tissue, and with especial ease in the delicate prosen- 
 chyma surrounding the vessels; while when the absorption is 
 hastened and superabundance of fluid present, the vessels also 
 take part in the conduction of the sap, at the same time propor- 
 tionately parting with the air they contain. 
 
 2. Behaviour of the Ascending Sap in ABNORMAL absorption. 
 
 Salix alba. Absorption through the exposed wood. A young 
 leafy shoot 10 inches long was stripped of its bark for 2 inches 
 at the bottom, and dipped 1 inch in the solution ; 2 inches of 
 bark were also removed at the upper end, and this part rolled 
 up in blotting paper. Then, to prevent drying, a glass tube 
 closed at the upper end was passed over the upper half of the 
 shoot. After one day the paper was already moist and reacted 
 strongly blue ; after six days the shoot was analysed ; it was 
 filled in all parts with the saline solution, especially, however, 
 in the wood-vessels which were gorged with sap up to the very 
 top; much salt had crystallized out on both surfaces of the 
 leaves, especially at the bases. Here, with the mouths of the 
 vessels of the wood standing open, a rapid ascent was observed 
 not only in the longitudinal direction, but also horizontally, into 
 the blotting paper in contact only with the alburnum, 
 
OF SAP IN PLANTS. 41 
 
 Salix alba. A young leafy shoot 12 inches long was stripped 
 of its bark for 2 inches at the bottom, and dipped 1 inch in the 
 fluid ; 1 inch below the top (the upper oblique cross section of 
 the shoot) an annular piece of bark 3 lines wide was removed. 
 Protected from drying as before. After six days the salt was 
 found to have ascended into the very apex, and indeed into all 
 parts, but most strongly in the medullary sheath. This con- 
 tained dark blue dotted vessels and unreliable spirals. Only the 
 epidermis of the upper piece of bark gave no reaction. 
 
 S. alba. A piece 12 inches long was cut out of a young leafy 
 shoot, 2 inches of bark removed at the bottom, and dipped 
 
 1 inch into the solution. In the upper part a little ring of bark 
 was cut out, and the whole allowed to stand without protection 
 from evaporation. After six days, all parts, up to the top of the 
 shoot, even the externally dry, exposed part of the wood which 
 had been laid bare, gave a reaction. At the extreme point the 
 vessels of the medullary sheath no longer took part, but the 
 inner prosenchymatous cells of the wood reacted deep blue. 
 
 From these experiments it is seen how little share the bark 
 takes in the conduction of the sap, and how readily a horizontal 
 movement of the sap takes place from the gorged young wood 
 into the bark, 
 
 S. alba. Absorption through the bark. A piece 12 inches 
 long, of a young leafy shoot, was taken and the bark slit up 
 
 2 inches from the bottom drawn back, and the exposed cylinder 
 of wood, 2 inches long, removed ; then the lower end (merely 
 bark) was dipped 1 inch into the solution. After six days the 
 shoot was found remarkably dry, from insufficient supply of 
 fluid. Analysis. The whole of the stripped piece of bark, even 
 the epidermis, reacted strongly. The wood had likewise ab- 
 sorbed fluid from the bark into all parts at the lower end, but 
 not uniformly ; particular vessels and cells did not react at all. 
 Cross section 2 inches higher up. The bark and medullary 
 sheath had absorbed most, the pith least. At 3 inches distance 
 from the lower end of the wood, the salt was found only in liber 
 and wood ; the epidermis and pith no longer reacted. 
 
 Consequently, under favourable circumstances, a movement of 
 the fluids in the bark, and horizontally from the bark into the 
 wood, undoubtedly occurs, although to a very slight extent. 
 
42 HOFFMANN ON THE CIRCULATION 
 
 The isolating power of the epidermis against moisture is worthy 
 of notice. 
 
 B. THE DESCENDING SAP. 
 
 It seemed advisable in this case also to examine the different 
 conditions separately, since it must be influential whether the 
 fluids ascend from the uninjured roots before descending from 
 the peripherical parts of the stem, or make their way down di- 
 rectly from the leaves, or from the points of cut shoots, &c. 
 
 1. The Descending Sap when absorbed through the LEAVES. 
 
 To warrant this experiment on physiological grounds, it suf- 
 fices to refer to the fact of such a condition occurring in nature 
 in every fall of dew or rain, wherein it in fact constitutes a 
 condition essential to the well-being of plants. 
 
 Salix fragilis, L. On June 7th a large uninjured leaf was 
 immersed in the solution, and on the 10th the shoot which bore 
 it was cut off. Analysis. In the outer part of the shoot all the 
 systems reacted ; nearer the base at length only isolated tracheae 
 of the wood, and to the greatest distance on the side of the twig 
 on which the leaf arose. 
 
 S.fragilis, L. Experiment as before, with the modification 
 that the larger shoot which bore the absorbing twig was notched 
 deeply on the corresponding side. In three days the solution 
 could be traced in the absorbing twig, farthest in the dotted 
 vessels of the woody layer, and above all in the unreliable spirals 
 of the medullary sheath. In the main shoot the fluid had de- 
 scended over the boundary between the inner and outer layers 
 of wood, but not beyond the notch. 
 
 S.fragilis, L. Fresh leaves of a young twig were immersed 
 one after another for several days in the solution, until a large 
 quantity of it had been absorbed. The main shoot which bore 
 the absorbing twig was ringed 3 lines broad down to the wood, 
 and the ring of bark removed. Analysis after twelve days. In the 
 peripherical part of the absorbing twig all systems had again 
 absorbed, but only the medullary sheath conducted far down ; 
 from this the fluid had passed out to the cicatrices of the partly 
 fallen leaves, while the buds in the axils of these, at that time 
 without any vascular connexion with the medullary sheath, 
 were wholly passed over. It had descended a good way in the 
 
OF SAP IN PLANTS. 43 
 
 interior of the wood of the main shoot, and here again at the 
 boundary between the outer and inner layers of wood (but espe- 
 cially in the latter), while in the bark and liber it had not reached 
 the ringed portion, much less passed beyond it. The fluid had, 
 moreover, not merely descended, but also ascended, in the main 
 shoot, and in the same region of the woody system. In the 
 absorbing twig itself it likewise passed into the leaves situated 
 below the absorbing leaves, and could readily be detected in the 
 unreliable spiral vessels of their petioles. It must be observed 
 that the two layers of the wood differed very much in their whole 
 character ; the outer was gorged with sap and evidently still in 
 active process of development (June 27th), while the inner was 
 white and dry, and therefore much better fitted to convey the 
 crude juices. It therefore only remains remarkable, that the fluid 
 which penetrated most easily in the medullary sheath of the twig, 
 left the neighbourhood of the pith in the main (older) shoot, and 
 passed to vessels situated further out. I observed the same in 
 Salix acuminata, Smith, in which the solution was traced 
 through three communicating generations or systems of branches. 
 The still green absorbing twig behaved as above ; the shoot from 
 which this arose possessed three layers of wood ; in this also the 
 fluid had descended chiefly near the pith. The second shoot 
 passed into (or arose from) a third thicker branch in the wood, 
 in which four layers could be distinguished, and here the fluid 
 had passed down at the boundary between the inmost and the 
 next succeeding layer of wood, and not next the pith. It perhaps 
 would not be erroneous to attribute this circumstance to the 
 difference of the annual course of growth, assuming that the 
 fluid always kept to one and the same tract, to vessels of the 
 same age, in passing from the youngest shoot into the older. 
 At all events this is not contradicted by the observed occurrence 
 of several layers of wood, for I have seen distinctly (in Salix 
 alba) that at least three succeeding systems (or generations) of 
 shoots may be developed in one and the same year, the lowest 
 and thickest containing two clearly distinguishable layers of 
 wood, which however were indicated even in the last and thinnest 
 (in the beginning of July). In order therefore to obtain a surer 
 basis for the decision of the differences of age in the young 
 systems of branches, I examined the condition of that small 
 
44 HOFFMANN ON THE CIRCULATION 
 
 vascular bundle which diverges at certain points from the me- 
 dullary sheath, and runs into the petiole of the leaf which 
 subtends the bud. Subsequently (in the succeeding year), these 
 vessels, which are torn off externally at the fall of the leaf, are 
 covered up and buried by degrees by the new wood formed in 
 the young shoot (produced by that axillary bud) ; but they may 
 still be discovered, even in old branches, if carefully sought. In 
 the above case, in Salix acuminata, it was found that the saline 
 solution had descended in the old main shoot, as mentioned, 
 between the innermost and next succeeding layer of the wood, 
 and thus externally over that little vascular bundle (originally 
 going to a leaf) belonging to the inmost layer of wood. 
 
 Balsamina hortensis. The solution absorbed by the leaves 
 could in three days be traced upwards in all parts and farthest, 
 and downwards in thevessels and the (wood) prosenchyma accom- 
 panying them ; the latter, however, had conducted very much 
 more fluid, since in cross sections the colourless large vessels 
 were ordinarily perceived surrounded by a delicate ring of very 
 small blue cellular points. In another case also, when the plant 
 had absorbed very little of the solution, it was observed that this 
 had descended principally in the internal cortical layer, and in 
 the prosenchymatous cells in the vicinity of the vessels, not how- 
 ever in the latter themselves. 
 
 While, therefore, the tracheae conducted most readily in woody 
 plants,inthe succulent balsam the neighbouring prosenchymatous 
 cells were decidedly overcharged. Perhaps the cause lay in the 
 prosenchymatous cells of the woody plants being in many cases 
 filled with air (which is not the case in the balsam), whereby, 
 of course, the passage of the solution from cell to cell through 
 the, moreover dry, membranes might be rendered more difficult. 
 
 Lactuca sativa. The solution absorbed by the leaf during 
 eleven days was contained in especial abundance in the spiral 
 vessels and their surrounding prosenchyma, on the corresponding 
 side ; on the other side of the stem, however, only in the pros- 
 enchyma surrounding the vessels, and in the lower parts of the 
 stem the same. Here, moreover, the rind and the pith also had 
 conducted, the pith principally in the cells at the boundary of 
 the medullary cavity. 
 
 Euphorbia terracina, L. After four days' absorption through 
 
OF SAP IN PLANTS. 45 
 
 a leaf, the solution was traced in the entire stem, chiefly in the 
 wood cells and isolated tracheae (unrollable spirals and dotted 
 vessels), which latter also contained a few air-bubbles at the same 
 time. 
 
 Tropaeolum majus. After five days' absorption the solution 
 was found inside the intercellular passages of the rind and pith, 
 stiil more in the prosenchyma of the wood, and most of all in 
 some tracheae. 
 
 Cucumis Melo. After one day's absorption all the intercellular 
 passages, for several inches upwards and downwards in the stem, 
 were found filled with the saline solution, while the fluid cell- 
 contents themselves did not react; particular portions of the 
 (wood-) prosenchyma, and above all some of the large tracheae, 
 had also absorbed. 
 
 The size of the vessels here permitted a decision, for this and 
 all other cases, of the question whether the blue reaction so often 
 observed in the interior of the exposed tracheae might not result 
 from the process of preparation, in short from the cutting of 
 the sections, since the knife might indeed readily spread reacting 
 fluids from the neighbouring prosenchymatous cells into the 
 open mouths of the vessels. If such were the case, if therefore the 
 reaction in the interior of the vessels were exclusively caused by an 
 unavoidable smearing at the time of the analysis, the blue vas- 
 cular points arising from the reaction would not, at all events, 
 always occupy the same place in a succession of transverse slices 
 from a stem where the course of the vessels was exceeding 
 straight. But this actually took place, and it follows beyond 
 doubt that the tracheae can in some cases take up and carry 
 forward fluids. 
 
 Vitis vinifera. Here again it was found that the fluid pro- 
 ceeded both downwards and upwards from the absorbing leaf 
 into the shoot bearing it, and in both cases in the same situation, 
 namely, chiefly in the medullary sheath and in the portions of 
 cellular tissue enveloping the liber-bundles on the inner side; 
 apparently somewhat more had descended externally, and some- 
 what more ascended internally. 
 
 Cucurbita Pepo. This time a tendril, instead of a leaf, was 
 immersed in the solution, but it absorbed very little, probably 
 in consequence of continued wet weather. Analysis showed 
 
46 HOFFMANN ON THE CIRCULATION 
 
 that the fluid had ascended in the prosenchyma accompanying 
 the vessels, but not in these themselves. 
 
 From these and similar experiments it follows that in the ab- 
 sorption of fluids through the leaves, they are conveyed most 
 readily by the tracheae or the prosenchyma closely surrounding 
 these; in plants gorged with sap more readily in the latter, and 
 the reverse in diy woody plants. But even in the most succu- 
 lent vegetables, only a somewhat longer continuance of the in- 
 troduction of the fluid, or a greater quantity of it, is requisite to 
 cause it to pass very readily into the air-tubes, and at length 
 into all parts. It would therefore be erroneous to assume that 
 any particular anatomical system is exclusively charged with the 
 conveyance of un elaborated fluids in the ascending or descending 
 direction. It was above all seen, that the trachea? do usually 
 convey air in summer, but very readily become temporarily 
 more or less, or even wholly filled with fluids which displace the 
 air. In fact, chemical reasons led me to consider the existence 
 of the gas in the spiral vessels and spiroids as nothing more 
 than a result of the absorption of crude fluids from the soil, which, 
 ascending in the higher and warmer layers of the plant, at once 
 give off almost unaltered the gases dissolved in them, these being 
 diffused through those communicating passages, and so gra- 
 dually evaporated outwards and upwards without doing any 
 mischief. In this point of view the vessels would be regarded 
 as 4 tubes of safety. 5 
 
 It merits some attention, that, as the last experiments prove, 
 no parts take so little share in the conduction of the solution 
 downward as the layers of the bark. I therefore took occasion 
 to investigate the capability of the bark to convey fluids by a 
 direct experiment. This was done by removing every other 
 passage but the bark from the descending fluid. 
 
 Salix vitellina. On the 1 9th of June a fresh pendent twig 
 1^ line in diameter, had the bark slit up for the length of 1 inch 
 at the side, 5 inches from the end ; the bark was turned back 
 and the wood within completely removed for a length of 2 lines ; 
 then the bark was returned into its place, rolled up in a living 
 leaf to prevent drying, and the shoot strengthened by a splint. 
 Lastly, a leaf situated below the excised wood was immersed in 
 the solution. After twenty-four hours the fluid had advanced 
 
OF SAP IN PLANTS. 4? 
 
 very little in the pith, but elsewhere in all parts (bark and liber 
 included) as far as the cross-section of the wood, but not beyond 
 this even in the bark. The result was similar after absorption 
 for four days. Even after seven days 5 absorption, the solution 
 had not made its way over the bridge of bark ; indeed this did 
 not itself react, although it was in part perfectly fresh and living. 
 In this case, moreover, the whole of the lower outer part of the 
 twig was densely filled with the saline solution ; even the badly 
 conducting pith of the lower portion of wood reacted distinctly ; 
 the medullary sheath and the peripherical portion of the wood 
 reacted most strongly, especially on that side of the wood corre- 
 sponding to the absorbing leaf. From this it is evident that a 
 far stronger penetration of the fluids than that which occurred 
 here, is requisite to overcome the resistance which liber and bark 
 oppose to the descending sap (see Sect. 4 below). 
 
 This observation rendered it necessary to apply the saline 
 solution immediately to those parts to which the business of 
 conveying the sap down is most frequently attributed, in order 
 to bring the question nearer to a decision. 
 
 2. The Descending Sap with direct absorption by the CAMBIUM 
 
 layer. 
 
 Salix acuminata, Sm. In a branch 1^ inch thick, the bark 
 was slit up, separated to a certain extent, and a piece of filtering 
 paper, many folds thick, soaked in the solution, inserted under 
 it, the wound being then loosely bandaged. After one day 
 (June 15) it was found that the salt had neither ascended nor 
 descended beyond the exposed portion of the wood ; it had only 
 penetrated extremely superficially even in the liber which lay 
 directly upon the paper, and not at all into the rest of the bark 
 or the wood. 
 
 Salix arbuscula, Whlbg. Bark slit up for 2 inches ; branch 
 1 1 inch thick : otherwise as above. After four days, only those 
 parts directly in contact with the paper reacted ; the salt had not 
 passed beyond in any direction ; the paper was still moist. 
 
 Salix hippophaefolia. Branch 1 inch thick ; bark slit up as 
 in the preceding, but the fluid was actually dropped in on the 
 18th and 19th of June. On the 20th it was found that the 
 solution had not gone beyond ; even the layer of sap-wood was 
 scarcely penetrated Jth of a line deep. 
 
48 HOFFMANN ON THE CIRCULATION 
 
 Salix arbuscula. Branch 1J inch in diameter. Repeatedly 
 wetted, as in the preceding case, during eight days: result 
 almost the same. The solution had only advanced 1 line beyond 
 the exposed spot, and quite uniformly upwards, downwards, and 
 to the side ; the sap-wood reacted of a line deep. When the ex- 
 periment was continued for eighteen days the result was the same. 
 
 Consequently there is no layer in the whole tree less favour- 
 able than the cambium for the conduction of the sap. In oppo- 
 sition to the views of many inquirers, this part, being in the 
 most active condition of development, most energetically arrests 
 the fluids. 
 
 It is clear how unfitted the bark is for the transport of fluids ; 
 they occupy a longer time there than in most other parts, in 
 changing their place. And in this experiment, we must not be 
 led away by the results of what are called the " magic rings*" 
 on trees. For if a thickened border is formed on them at the 
 upper cut edge, this only proves that the sap in general has a 
 descending motion ; not, however, that this does not take place 
 far better and more easily in the totally uninjured woody layer. 
 When we reflect that even in the oldest trees a continual in- 
 crustation of the cells, a continual increase of that transforma- 
 tion of the saps, goes on deep in the interior of the wood, the 
 result of which is the concentric growth of the heart-wood, at the 
 expense of what is at first sap-wood, it is seen at once that it 
 would be a great mistake to regard the wood, on account of its 
 solidity, as lifeless and unengaged in the conduction of the sap. 
 
 3. The Descending Sap in absorption by the ROOT. 
 
 Salix alba, L. A piece 1 foot long, of a shoot an inch 
 thick, was placed in the ground on the 24th of February, and 
 kept at a moderate temperature, so that roots were formed, and 
 by the 20th of April leaves had already burst out. On the 6th 
 of June the rooted portion was carefully split up the middle, 
 from below upwards, and one of the halves immersed in solution 
 of the ferrocyanide, the other in a vessel of pure water standing 
 close beside. On the 14th all the leaves were dead, the roots 
 still fresh and healthy. On the 4th of July the height of the 
 fluids in the two vessels was not perceptibly altered, whether the 
 levels were previously alike or different, as counter- experiments 
 * Made by removing a ring of bark running all round the tree. 
 
OF SAP IN PLANTS. 49 
 
 proved ; therefore no siphon action had been exerted. On this 
 day the twig was analysed. The solution had not only ascended 
 to the upper end in the one part, but also descended in the other 
 part (at the water side), and indeed just to the surface of the 
 water ; it had penetrated farthest of all in the vascular part of 
 the outermost wood, which, at the upper part, was in contact 
 with the absorbing half of the shoot ; in the liber and bark it 
 fell about 1 inch short of this, while the inner wood, the medul- 
 lary rays, and the pith, did not react. The surrounding water 
 exhibited no reaction, which, it may be remarked in passing, 
 does not speak much in favour of the hypothetical "root-secre- 
 tion/' The half dipping in the saline solution, when examined 
 upwards, reacted most in the medullary sheath, and in the (two) 
 outer layers of wood ; also, however, in the liber and bark ; while 
 the inner (third) layer of wood and the pith had not conducted 
 so far. At the upper free and undivided extremity, the branch 
 reacted only at one side, that corresponding to the vessel con- 
 taining the saline solution ; therefore the solution had not 
 passed round by the top to descend into the other half (to the 
 water), but had gone over (in extremely small quantity) hori- 
 zontally from wood to wood further down. 
 
 When the experiment was stopped sooner, in other cases, it 
 was found (June 12th) that the solution had merely ascended, 
 and not descended ; in another piece of a shoot, the solution had 
 descended half way in the water-half by the 15th of June. In 
 one case, when the experiment was kept in action longer, the 
 solution had descended \ an inch down below the level of the 
 water in the half dipping in the latter,- not, however, to the 
 highest of the little roots ; here also the water exhibited no re- 
 action ; in fact, the portion of the inner layer of wood here laid 
 bare by splitting the shoot had not conducted. 
 
 Whether, in these cases, the absorption of the saline solution 
 took place through the roots, or also through the lowest exposed 
 portion of the inner layer of wood, it is certain that here again 
 the liber and bark were decidedly less concerned than the tra- 
 cheae of the wood, in the descent of the sap. It is seen that the 
 descending sap, when it ascended from the roots and penetrated 
 horizontally from wood to wood, avoided the medullary sheath, 
 while it was shown in previous experiments that it very readily 
 
 SCIEN. MEM. Nat. Hist. VOL. I. PART I. 4 
 
50 HOFFMANN ON THE CIRCULATION 
 
 passes into the latter when it is brought into the plant by the 
 leaves ; a circumstance which is doubtless to be explained by the 
 intimate anatomical connexion between the vessels of the me- 
 dullary sheath and those of the petioles in young shoots. 
 
 4. The Descending Sap after direct absorption by CUT SURFACES 
 
 OF THE WOOD. 
 
 Salix vitellina. The end of a pendent young leafy shoot was 
 cut off, and the lower peripherical portion stripped of bark for 
 2 inches ; the part thus laid bare was immersed 1 inch in the 
 solution. At 2 inches further up in the same shoot, the bark 
 was slit up at the side, and the cylinder of wood cut out for a 
 length of 2 lines ; the bark being returned to its place, and the 
 wound wrapped in fresh leaves, the whole shoot was supported by 
 a splint, to keep it in a fixed position. After four days the shoot 
 had absorbed the fluid as far as it dipped in it. In this case 
 the saline solution had passed the bridge of bark, had advanced 
 4 \ inches beyond the vacancy in the wood, and into all parts ; 
 furthest, however, in the bark and wood, principally in the me- 
 dullary sheath and the peripherical part of the wood. Repeated 
 experiments gave the same result, but sometimes the liber, some- 
 times the wood, had conducted a little farther. Consequently, 
 here, where a forced entrance of the fluid had accomplished the 
 passage through the bridge of bark, the solution had again 
 penetrated in the horizontal direction through the wood above 
 this bridge, and sometimes even advanced further in it than in 
 the bark itself. 
 
 S. alba. A portion 1^ foot long of a leafy young shoot 
 was stripped of its bark for 2 inches at the upper end, and 
 dipped, with its wood wrong end upward, 1 inch deep in the 
 solution. Then 1 inch of bark was peeled from the other free 
 end, and a closed glass tube turned down over it to prevent de- 
 siccation. After seven days the fluid had ascended through all 
 parts; whence, comparing this with the cases mentioned in 
 section A 2, it results, that in absorption by exposed layers of 
 wood, it makes no difference in the conduction of the sap whether 
 the shoot is immersed in the fluid upright or in a reversed posi- 
 tion. In this case also, some salt had crystallized out upon the 
 leaves. When the free end of the wood was enveloped in blot- 
 
OP SAP IX PLANTS. 51 
 
 ting paper, the latter absorbed a great deal of the solution (in the 
 horizontal direction from the wood) even when the bark much 
 lower down was unaffected. Or if only a ring of bark was cut 
 out on the upper part of the shoot, this interruption was no 
 hindrance to the advance of the solution ; it was found at the 
 end, both in the wood and in the bark. The epidermis did not 
 give a blue reaction even after remaining one hour in contact 
 with the salt of iron. 
 
 Salix acuminata, Sm. The question investigated in this case 
 was, how far a horizontal conduction of the fluids can take place 
 under favourable circumstances in the wood itself, through layers 
 of different ages. For this purpose the point of a small twig 
 was cut off, at the end of June, and the open end immersed in 
 the solution. The main shoot (6 lines thick) which bore the 
 foregoing was so notched circularly in four different places, that 
 there was no immediate communication with the vessels of the 
 stem in any place : the wounds were enveloped in fresh leaves. 
 After eight days it was found that the solution had advanced 
 exclusively in that side of the main shoot which corresponded to 
 the absorbing twig, and indeed only as far as the notch which 
 interrupted the vascular communication 4 inches further up. 
 Here also the outermost layer of wood and the liber had conducted 
 principally, and not the cellular intermediate layer of the bark. 
 From this we see what difficulties are opposed to the assumption 
 of a horizontal movement of the sap through the medullary rays; 
 although, at the same time, a horizontal movement of the saps in 
 the young wood, generally, under very favourable circumstances, 
 as in the experiments of Hales (/. c.), cannot be disputed. 
 
 Postscript. With regard to the behaviour of the milk-sap, 
 which I had an opportunity of observing in several Euphorbia, 
 in Sonchus oleraceus, &c., in reference to the conduction of sap, 
 I am led to assume, from all that I could notice, that it takes no 
 part whatever in this, whether the fluid penetrate into the plant 
 through the leaves or through the roots, setting aside all the 
 anatomical reasons against a circulation of the milk-sap, the most 
 decisive of which is, that in the majority of plants the milk-sap 
 passages have no continuity or general distribution. [A.H.] 
 
52 MULLER ON THE MALE OP 
 
 ARTICLE II. 
 
 Upon the Male of Argonauta Argo and the Hectocotyli. 
 By Professor HEINRICH MULLER of Wurzbury. 
 
 [From Siebold and Kolliker's Zeitschrift fur Zoologie, June 1852.] 
 
 AMONG the many perplexities presented by the sexual rela- 
 tions of the Cephalopoda, we have had to reckon, even up to the 
 present time, the statement of the majority of observers, that 
 they had found none but female Argonauts. I believe that in 
 the present essay I for the first time describe the perfect male 
 Argonaut, as one of the arms of which the so-called Hectocotylus 
 Argonauts is developed. The Hectocoiyli, which, from the first, 
 Cuvier called " truly extraordinary 55 creatures, will none the 
 less deserve that title. 
 
 It is well known that Kolliker* has endeavoured to show that 
 the Hectocotylus of the Argonaut, described by Delle Chiajef 
 and afterwards by Costa J, is the male of this Cephalopod ; that 
 the newly discovered Hectocotylus Tremoctopodis also is the 
 male of Tremoctopus violaceus, D. Ch. ; and Von Siebold has 
 assented to his views. 
 
 More lately Verany||, in his work upon the Cephalopoda, 
 communicated some very important discoveries with regard to 
 the Hectocotylus of an Octopod. He found, that among five 
 specimens of a peculiar species which he had previously named 
 Octopus Carena, in three the third arm upon the right side was 
 longer and stronger than the others, and was provided with a 
 vesicle at its extremity. The fourth specimen had in the same 
 position a short pedunculated vesicle ; and the fifth possessed 
 simply the peduncle without either arm or vesicle. Filippi 
 noticed that the longer arm, which in one instance was observed 
 
 * Annals of Natural History, 1845. Linnaean Transactions, vol. xx. 
 Bericht von d. Zootomischen Anstalt zu Wiirzburg, 1849. 
 f Descrizione, iii. p. 137, tab. 152. 
 J Annales d. Sciences Nat. 1841, p. 184 and pi. 13. 
 Vergleichende Anatomic, p. 363. 
 || Mollusques Mediterraneans, 1^* partie, Genoa, 1847-51. 
 
ARGON AUTA ARGO AND T11K IIKCTOCOTYLI. 53 
 
 to drop off on being touched, resembled the Hectocotylus Octo- 
 podis of Cuvier*, and Verany concludes from thence that this 
 Hectocotylus Octopodis is a deciduous arm bearing male organs 
 which are probably periodically developed. With regard to the 
 Hectocotyli of the Argonaut and of Tremoctopus on the other 
 hand, Verany believes that they cannot be arms of the corre- 
 sponding Cephalopoda. 
 
 These statements rendered the subject of the Hectocotyli far 
 more difficult than ever. It could hardly be believed that the 
 Hectocotylus of the Octopus could be really distinct in its nature 
 from the two examined by Kolliker ; and yet upon the other 
 hand, there were many reasons for hesitating to apply the con- 
 clusions drawn from the former to the latter. The Hectocotylus 
 octopodis differs in many respects from the others ; its sexual 
 relations are less certain, while those of the Octopods to which 
 it was attached, either in the mantle or as an arm, are wholly 
 unknown ; and finally, the positive assertions of Madame Power 
 and Maravigno (see Kolliker, /. c.) seemed to prove that the 
 Hectocotylus Argonautce was developed as such in the ova of the 
 Argonaut. 
 
 While at Messina, in the past autumn, I was very desirous of 
 repeating the observations of Madame Power; but notwith- 
 standing the examination of many thousand ova of all the Ar- 
 gonauts which I could procure, I merely found embryos of the 
 ordinary form more or less developed ; never those vermiform 
 young, whose description had led to the belief that the Hecto- 
 cotyli were developed in especial bunches of ova. 
 
 At last, at the end of September and in the beginning of Oc- 
 tober, there were brought to me, among many very small Argo- 
 nauts which had not yet acquired a shell, a few of a quite pecu- 
 liar form. Their cephalic extremity presented a little sac, which 
 projected between the arms, as the animals swam about with 
 their peculiar retrograde movement. On closer inspection f one 
 could perceive seven arms, which all terminated in points like 
 the six lower arms of other Argonauts of the same size. The 
 
 * Annales d. Sc. Nat. 1829, p. 147, pi. 11. 
 
 f The relations of the parts were clearest when the animals fixed themselves 
 during life, within a glass, so that one could look from without straight down 
 upon the oval surface of the head ; or after death, by placing them in a waxen 
 pit so as to obtain a similar view. 
 
54 MULLER ON THE MALE OP 
 
 two upper and the two lower arms were longer than the lateral 
 ones ; of the latter on the right side three only were present ; 
 while on the left side there existed, in all the specimens which 
 I received, in the place of the lower lateral arm, the sac in 
 question, supported by a short and delicate pedicle, as if it were 
 constricted. The pedicle arose from a small depression between 
 the second and fourth arms and the mouth, from which the sac 
 could be easily drawn out a little. The membrane which unites 
 the base of the arms of the Argonaut passed upon the left side 
 from the second to the fourth arm, without immediately invest- 
 ing the sac, whose position was somewhat internal to it. 
 
 The sac itself was not so long as the arms in the smallest 
 specimens, whilst in the larger it equalled or exceeded them in 
 length. In shape it was not exactly round, but somewhat 
 elongated and compressed in such a manner that the diameter 
 in a radial direction from the mouth was greater than in the line 
 of the two neighbouring arms. The colour, like that of the rest of 
 the body, was intensely reddish brown when the chromatophora 
 were dilated, more greyish when they were contracted. Only 
 on the inner, oral side was there a white streak without chro- 
 matophora, which however did not extend over the whole length 
 of the sac. 
 
 In all cases a Hectocotylus Argonauts lay coiled up within the 
 sac. It was curved towards the side which bears the suckers, so 
 that the back of the thick part corresponded longitudinally with 
 the internal convexity of the sac. The part described by Kol- 
 liker as a silvery sac, forms at this place, immediately under the 
 skin of the sac in large specimens, a ridge-like elevation visible 
 externally, through which a whitish tint often glistens. The 
 thinner part of the sucker-bearing body is bent back along the 
 inner convexity of the sac towards the base, and the filiform ap- 
 pendage lies between them in multitudinous convolutions. 
 
 This position of the Hectocotylus is frequently obvious from 
 without, especially during the lively movements which it often 
 makes ; and still more clearly on the opening of the sac, when 
 it uncoils itself from its narrow cell under the eye of the spectator. 
 
 The relation of the Hectocotylus to the capsule in which it lies, 
 and the change which the latter undergoes after its eversion, 
 are very remarkable. 
 
ARGONAUTA ARGO AND THE II ECTOCOTYLT. 55 
 
 I may here observe, that in one case the sac burst before my 
 eyes, along the inner, oral side, in consequence of the violent 
 movements of the Hectocotylus, when the process about to be 
 described took place in exactly the same manner as in other spe- 
 cimens which were artificially opened. 
 
 It is observed, in the first place, that the thick end of the Hec- 
 tocotylus is fixed to the pedicle of the sac or forms it ; next, that 
 the membrane of the sac is perfectly distinct from the filiform 
 appendage and from the neighbouring parts of the sucker-bear- 
 ing body ; but that, upon the thick portion of the body, while 
 it leaves the sucker- side free, it is attached along the back behind 
 the suckers, and forms the covering of the silvery sac above men- 
 tioned. 
 
 The so-called pigmented testis capsule of Kolliker, however 
 (as it is observed in the Hectocotyli which are found free upon 
 female Argonauts), does not yet exist, and is subsequently formed 
 from the membrane of the sac. 
 
 As soon indeed as the appendage and the thinner part of the 
 body, which usually become twisted upon their axis at the same 
 time, are evolved, the thick part bends forcibly back in the op- 
 posite direction to the previous curvature, that is towards the 
 back. By this means the longitudinally cleft membrane of the 
 sac is inverted, so that its inner surface comes to be exterior, and 
 the edges of the torn part are turned back towards the back of 
 the Hectocotylus, which is now concave. The previously external 
 pigmented layer of the sac now lies in the pit between these 
 edges, and when the latter have united, there is left only a 
 small cleft, a process which can naturally not be directly traced. 
 We have just such a pigmented capsule formed as has been already 
 found in the dorsal crest of Hectocotylus Argonautae. 
 
 In this way we readily account for the singular fact, that a 
 colourless layer is constantly found upon the exterior of the 
 dorsal crest, while the layer of chromatophora lies internally 
 upon the so-called capsule of the testis. 
 
 The membrane of the sac then belongs to the future Hectoco- 
 tylus. This was seen most clearly in that specimen in which, 
 as has been already noticed, the sac opened spontaneously ; for 
 upon touching the Hectocotylus frequently it detached itself from 
 its delicate pedicle so as to carry away the inverted sac with it. 
 
56 MUJLLER ON THE MALE OF 
 
 However, as the cleft in the sac had not extended quite so far 
 as the insertion of the pedicle, the first suckers still remained 
 hidden by the pigraented sac, whose borders began to be reverted 
 only opposite to the fourth sucker. 
 
 The case here cited hardly allows us to doubt that the Hecto- 
 cotylus once formed is intended to become detached from the rest 
 of the animal ; as might indeed already be concluded from the 
 fact that all the Hectocotyli seen by Delle Chiaje, Costa and 
 Kolliker, to which I can add thirteen others, were found sepa- 
 rated and associated with female Argonauts. Hence also it would 
 seem to be probable that the detachment of the Hectocotylus is 
 preceded by the bursting of the sac ; though I have found no 
 specimen in which when captured the Hectocotylus had already 
 made its exit from the sac. When and in what manner the 
 separation of the Hectocotylus^ and its transport to the female, 
 go on ; whether any act of copulation, for instance, takes place, 
 were points upon which I had no opportunity of making any 
 observations. 
 
 I will now first consider a few points with regard to the ex- 
 ternal and internal structure of Hectocotylus Argonauts, and I 
 will then compare the Hectocotyli of Octopus and Tremoctopus 
 with it. For the most part I have only to confirm Kolliker's 
 observations, though of course my interpretation of them must 
 be somewhat different. The name " Hectocotylus " may very 
 well be retained, without any implication of independent ani^ 
 mality. 
 
 Hectocotylus Argonautce. 
 
 As to external form, there were two portions to be distinguished 
 in all the Hectocotyli, whether free or enclosed in sacs, which 1 
 examined : the one thick, and carrying suckers ; the other called 
 by Kolliker the filiform appendage, thin and suckerless, but di- 
 rectly continuous with the former. 
 
 In the free Hectocotyli the body and its appendage sometimes 
 attained the length of an inch or more each ; in other cases, each 
 was some lines shorter. A few of the Hectocotyli which were 
 just set free from the sac had this latter size. In three speci- 
 mens, in which the body and head of the whole animal, as far 
 as the base of the arms, were about 4 lines long, the sucker- 
 bearing portion of the Hectocotylus-arm measured 8-10 lines, and 
 
ARGONAUTA ARGO AND THE HECTOCOTYLI. 57 
 
 the appendage about as much more. In an animal of 3 lines 
 long, each part of the Hectocotylus-avm was a few lines shorter. 
 The smallest specimen which I met with measured 2 lines to the 
 base of the arms ; body and appendage of the Hectoco(ylus-arm 
 each 3-4 lines. The length of the uninjured sac was about 
 1 line in an animal of 2 J lines ; on the other hand, it was 3 lines 
 in a specimen whose body, as far as the arms, was 4 lines long*. 
 
 At the thick end of the detached Hectocotyli is the point, 
 where the constricted axis must finally have divided ; it is drawn 
 a little towards the dorsal side, while the h'rst suckers project 
 somewhat forward. No trace of any rent is to be seen, but the 
 surface is quite smooth as if cicatrized, and the fringe which 
 unites the suckers upon their dorsal side is also present between 
 the oblique anterior pair, so that the one series of suckers passes 
 in a continuous curve into the other. 
 
 The point of transition of the thicker body into the filiform 
 appendage is sharply marked in all the free Hectocotyli and in 
 the larger enclosed ones. The suckers with the fringe which 
 unites them cease suddenly, the axis of the body becoming 
 thinner and passing into the appendage. In the smallest speci- 
 men before mentioned, on the other hand, the transition was far 
 more gradual. The suckers in the posterior broad part of the 
 body, which did not measure more than -15 of a line across, be- 
 came gradually smaller and more rudimentary, and finally ap- 
 peared as mere transverse elevations ; when they ceased the dia- 
 meter of the body was still O'l of a line. 
 
 The membranous lobes described by Kolliker at the origin of 
 the suckerless part of the body were present in all free Hectoco- 
 tyli ; but it could generally be clearly observed that there is pro- 
 perly speaking only a single lobe, which in its highest part 
 crosses the body of the appendage transversely, and then passes 
 gradually upon each side into a slight fold. These two folds 
 run along the appendage for a considerable distance : in one 
 case, the most elevated portion of the lobe was prolonged into 
 two elongated processes. The height of the transverse portion 
 
 * An eighth specimen, in which both the body and the unopened sac surpass 
 the above dimensions, is in the possession of M. Verany, who immediately re- 
 collected it on seeing my specimens. It had previously been brought by Krohn 
 from Messina. 
 
58 MULLER ON THE MALE OF 
 
 varied from an inch to more than half an inch (1 bis uber ''). 
 The fibrous tissue of which the lobe consists is contractile, and 
 frequently moves very vivaciously by itself. In the yet attached 
 Hectocotyli the lobe was in the same way more or less developed, 
 and was wanting only in the smallest specimen. This is un- 
 favourable to the view that the lobe is a residue of the torn sac ; 
 which might otherwise suggest itself, especially since the strong 
 resistant epithelium which externally coats the appendage is 
 absent upon the lobe. The edges of the lobe were generally 
 smooth and did not appear torn. 
 
 Of the tentacular cirrhi which Costa (/. c. fig. 2 a e and/) de- 
 picts at the anterior end of the Hectocotylus, I could never find 
 any trace, and I am inclined to believe that they were some ac- 
 cidentally adhering foreign bodies, since nothing could be lost 
 or torn away, in the Hectocotyli otherwise perfect, which were 
 taken out of the sac. 
 
 Such specimens as the latter are also important for the deter- 
 mination of the interpretation which is to be put upon the 
 dorsal pigmented capsule * and the position of the appendix in 
 it. Kdlliker has called this capsule the capsule of the testis ; 
 inasmuch as in one specimen he saw the filiform appendage 
 enter it through a cleft in the back, and become connected 
 therein with a coil of seminal canals, to which he gave the name 
 of f testis/ I believe that the presence of semen there is acci- 
 dental, and that another interpretation must be given to the 
 position of the appendage. It has been already stated, that 
 there exists no capsule in the Hectocotyli while still included 
 in the sac ; the appendage is always free, and nothing is to be 
 seen of any seminal canals. In the free Hectocotyli the capsule 
 was indeed always formed, but in many instances it was quite 
 empty, the appendage also lying outside it. In other cases the 
 appendage passed, in the manner depicted by Kolliker (pi. 1. 
 fig. 9 and pi. 2. fig. 1?), through the cleft of the dorsal ridge 
 into the pigmented capsule, but lay free therein, no seminal 
 canals being present. 
 
 * The chroma topliora here exhibit in free Hectocotyli the same movements 
 as elsewhere. The radial muscular fibres are clearly recognizable, contracted 
 or relaxed according as the chromatophora appear large or small. Muscular 
 fibres are also found in the deeper layers of the cutis in Hectocotyli as else- 
 where among the Cephalopoda, e, g. in the dorsal ridge. 
 
ARGON AUTA ARGO AND THE IIECTOCOTYLI. 59 
 
 This could be seen partly upon opening the capsule, partly 
 from without during the movements of the Hectocotylus. The 
 appendage not only twisted about in the capsule, but crept al- 
 ternately out and in, so that even the thin part of the sucker- 
 bearing body, as far as it would go, became hidden in the cap- 
 sule. The Hectocotylus then crawled about in a very peculiar 
 manner with this inserted part, w^hich formed about the middle of 
 the body, directed forwards. On the other hand, if the Hecto- 
 cotylus were disturbed by touching, it not unfrequently drew its 
 appendage quite out of the capsule, and could then be no longer 
 distinguished from the first form which has been mentioned. 
 
 It appears then, that the appendage makes the pigmented 
 capsule its residence either from being accustomed to its pre- 
 vious imprisonment in the sac, or as a sort of presentiment of its 
 proper position *. 
 
 The exceptional occurrence of seminal canals in the capsule 
 of Kolliker's Hectocotylus is explained, if we consider the route 
 which the semen must take to be poured out. 
 
 Kolliker has exactly described the course of the vas deferens 
 between an aperture in the neighbourhood of the point of the 
 appendage and a thick silvery sac which lies under the pigment- 
 capsule. He called that sac a penis, or finally, vesicula semi- 
 nalis ; assuming that the semen passes out of the capsule 
 (testis) along the appendage, then into the ductus deferens 
 along the back, and finally out of the silvery sac at the thick 
 end of the Hectocotylus. 
 
 However, in the most free Hectocotyli, and even in the 
 largest of the included ones, we find this sac completely filled 
 with semen. Sometimes this distension extends into the ductus 
 deferens to a greater or less extent, and evidences itself to the 
 naked eye even, by an intense white streak along the back and 
 appendage of the Hectocotylus. Lastly, on one occasion a Hec- 
 tocotylus passed a whole coil of a thread, about '06 of a line thick 
 and consisting of spermatozoa, from the aperture of the append- 
 age, and the thread remained attached to it, so that the appear- 
 
 * Considering the occurrence of gills in Hectocotylus Tremoctopodis, we 
 might ask whether that form clevelopes a digestive organ, for which Cuvier 
 took the capsule in //. Ocfopodis. At present however we have no evidence 
 upon the point. 
 
60 MULLER ON THE MALE OF 
 
 ance figured by Kolliker (pi. 2. fig. 19) arose: only the ap- 
 pendage was free, while in Kolliker's specimen it was inserted 
 in the pigmented capsule. 
 
 We may hence assume that the semen during ejaculation passes 
 fromthethickersactowards the point of the appendage*. It agrees 
 very well with this conclusion, that a copulation very probably 
 takes place during which the appendage represents the penis 
 (vide infra). Kolliker's Hectocotylus therefore only committed 
 an error loci when it deposited its semen in the pigmented cap- 
 sule. The presence of an investment to the seminal coil w T hich 
 Kolliker found in the pigment-capsule, is not, as I believed at 
 first, any argument against its secondary deposition there, for a 
 structureless layer was also very visible in the free seminal cy- 
 linder, at least in some portions of it. It is perhaps only 
 analogous to the structureless mass which is to be found else- 
 where in the sexual canals of the Cephalopoda, and is deposited 
 around the semen when excreted. In a second instance I could 
 find no such investment. 
 
 Since the pigmented capsule upon the back of the Hectoco- 
 tylus could not be the testis, the latter was to be sought for 
 elsewhere. At first, I was tempted to consider the silvery sac 
 as its representative ; since not only was this full of perfect 
 spermatozoa in all free Hectocotyli, but also in that Hectocotylus- 
 arm already referred to which had burst its sac after its spon- 
 taneous detachment. Nevertheless it was surprising that in 
 other Hectocotylus-arms just taken out of their sac, the silvery 
 capsule had not its white colour, and neither perfect semen nor 
 any stages of its development were to be perceived therein. 
 
 Subsequently I convinced myself that there is unquestionably 
 a testis in the abdomen of the animal which carries the Hectoco- 
 tylus as an arm. Behind the gills and venous appendages a 
 great part of the mantle- cavity is taken up by a capsule, whose 
 free lower wall is very remarkable on account of its isolated 
 chromatophora scattered over as hining golden ground. Behind, 
 
 * In most cases I could not exactly make out the place of the aperture, though 
 in the two upper thirds of the appendage the ductus deferens is usually easily 
 recognizable, and even far forward has a diameter of 0'05 of a line when it is 
 not collapsed. On one occasion I succeeded in pressing the semen from the 
 silvery sac to within two lines of the point where the ductus deferens only 
 measured 0-03 of a line. 
 
ARGONAUTA ARGO AND THE I1ECTOCOTYLI. 61 
 
 it adheres to the mantle. In the capsule lies a white mass which 
 consists of little cylinders or caeca which are united at one ex- 
 tremity: their length is about 1 line, their thickness 0'06-'l 
 of a line. A clearly-defined tunica propria could not be distinctly 
 recognized in these spirit specimens for each cylinder, but ex- 
 panded membranous coverings could be frequently observed 
 between them. In the cylinders themselves large pale cells lay 
 at the periphery ; the interior was in one case occupied by masses 
 which consisted of numerous granules of about 0'002 of a line 
 in diameter, and which had frequently a delicate process in an 
 oblique direction with regard to the axis of the cylinder. In a 
 second specimen there could be no doubt that these lumps were 
 forms of the development of the spermatozoa. There lay in the 
 same position more or less developed bundles of spermatozoa, 
 whose somewhat wavy threads had the same oblique direction 
 with regard to the axis of the little cylinder. This appeared, 
 consequently, to be quite a fibrous streak. The length of the 
 single bundles was about 0'08 of a line. 
 
 In these two animals provided with full testes, the generally 
 white and distended capsule of the Hectocotylus was colourless 
 and collapsed. In a third animal again, which had carried the 
 detached Hectocotylus-wm filled with spermatozoa, the shining 
 golden capsule was indeed present, but it was empty. If we 
 connect all these facts together, it becomes very probable that the 
 semen is produced in the testis, and that it is then transferred 
 into the Hectocotylus, although I could not recognise with cer- 
 tainty this portion of the ductus deferens, which must lie under 
 the skin of the head. 
 
 The silvery capsule, then, would be neither penis nor testis, 
 but vesicula seminalis ; and so long as the Hectocotylus remains 
 connected with the rest of the animal, the essential distinction 
 from other cephalopod males must consist in this, that the aper- 
 ture of the ductus deferens, instead of lying in the man tie- cavity, 
 is placed at the end of the peculiarly-developed arm. 
 
 The structure of the silvery capsule harmonizes very well with 
 this interpretation. It is, as Kolliker has shown, very muscular *, 
 and in its interior there lay in all the free, and in the largest of the 
 
 * The muscular fibres are distinguished from those of the rest of the bodv by 
 a peculiar development, a point to which I shall recur elsewhere. 
 
62 MULLER ON THE MALE OF 
 
 included Hectocotyli, the coils of a thread of 0'06-0'08 of a line 
 in diameter, consisting of perfect spermatozoa. I have not seen 
 the aperture of this organ, stated to exist by Kolliker at the ex- 
 tremity of the thick end of the Hectocotylus. If the semen be 
 actually passed out of the testis into the capsule, such an open- 
 ing must exist at one period or other ; but it probably becomes 
 closed behind the deposited semen before the detachment of 
 the Hectocotylus takes place. 
 
 The spermatozoa of the Argonaut consist of a very delicate 
 thread, at one of whose ends is a somewhat thicker fusiform 
 body. They are therefore analogous to those of Tremoctopus, 
 but smaller, since they measure, as we see especially in the 
 bundles, only 0'08-0'09 of a line in length, of which we may 
 consider the body to form O'Ol of a line. In general the bodies 
 lie grouped together, and from them the threads pass nearly 
 parallel, like the cilia of a colossal ciliated epithelium. On one 
 occasion almost every bundle of bodies was spirally twisted. 
 This occurred in the appendage of a Hectocotylus which I found 
 in the ovarian capsule of a female Argonaut. In this one case I 
 saw a lively movement in the spermatozoa, the groups of which 
 formed regular progressive waves like the sea after a strong 
 breeze. 
 
 What is there in the muscular tube which forms the axis of 
 the Hectocotylus ? is a most important question. 
 
 Since we know that the Hectocotylus is developed as an arm, 
 it may be surmised, a priori, that the structure of the whole 
 axis will nearly resemble that of other arms, as indeed Kolliker 
 has already shown it does, so far as the muscular tube is con- 
 cerned. In fact, there lies in its interior a chain of ganglia, 
 which answer to the suckers. We see them best in longitudinal 
 sections which have been placed in solutions of chromic acid or 
 corrosive sublimate, and the single ganglia may be separated and 
 demonstrated as far as the root of the filiform appendage. From 
 this point the muscular tube may be very readily traced to the 
 extreme end, but it is difficult to make out what it contains : 
 certainly not the vas deferens ; for this, as Kolliker has shown, is 
 only attached superficially. In fresh specimens I saw a few times 
 a clear tube-like streak, which gave off lateral branches as well 
 in the axis of the sucker-bearing portion as in that of the 
 
AUGONAUTA ARGO AND THE HECTOCOTYLI. 63 
 
 appendage, in which it measured only '012 of a line; but 
 of its nature I can say nothing. The thickness of the whole 
 axis measured in one case at the end of the seminal capsule 
 0-39 of a line ; towards the end of the sucker-bearing portion 
 0'3 of a line; in the beginning of the appendage 0' 15 of a line ; at 
 the end of it 0'03 of a line. The inner tube measured at the 
 same points O24, O18, 0*08, and 0'025 of a line. 
 
 The development of the Hectocotylus as an arm, while it ex- 
 plains the presence of a ganglionic chain, equally accounts for 
 the absence of any special organs of sense. But on this ground 
 the sensibility of the skin is very considerable. 
 
 Since the muscular tube is filled by the chain of ganglia, the 
 supposition that an intestinal canal exists there, which Kolliker 
 himself considered doubtful, must be given up ; at least I have 
 perceived nothing of the kind. 
 
 With respect to the circulation, I can unfortunately give no 
 information as to the connexion existing between the Hectoco- 
 tylus and the rest of the animal. In the separate Hectocotyli 
 the investigation is beset with difficulties, since they are for the 
 most part very restless, and wind and twist about in the most 
 determined manner. Yet a progressive wavy motion can readily 
 be observed in the trunks which lie upon each side of the back and 
 are immediately continued into the appendage. In one instance 
 I could distinctly perceive that this somewhat slow movement 
 passed upon the right side (the appendage being supposed to 
 be posterior and the suckers below) as far as the extreme point 
 of the appendage, and then returned in the opposite direction. 
 
 After each wave towards the point, however, there succeeded 
 not merely a centripetal one upon the other side, but centri- 
 petal movements frequently arose, which commenced from the 
 point of the appendage. In other cases I met with a different 
 rhythm in the longitudinal trunks of the one and of the other 
 side, and a few times it appeared to me as if in the same vessel 
 the movement went on sometimes in one sometimes in the other 
 direction, as in the Tunicata. However, two vessels lying close 
 together might readily cause a deception in this case. 
 
 Whether any distinct central organ of the circulation or heart 
 exist, I cannot as yet decide. 
 
 There occur indeed considerable dilatations in the vessels; 
 
C4 MULLER ON THE MALE OF 
 
 especially in one specimen, in which I found after the circulation 
 had ceased, a sacculated space '15 of a line long by *018-*08 
 broad in one of the longitudinal vessels of the back, somewhat 
 behind the extremity of the seminal capsule. At both ends of 
 the dilated portion more delicate lateral branches were given off. 
 Somewhat further behind upon the same vessel, and in a corre- 
 sponding position upon that of the other side, there was a 
 rounded expansion of '05--06 of a line in diameter. If these 
 dilatations are to be called hearts in which case they might be 
 considered to undergo a further development we must suppose 
 that such exist in many places, which would agree with the 
 general arrangement in the Cephalopoda. 
 
 But it may well be that these spots had merely remained ac- 
 cidentally dilated after death, for the narrower parts of the ves- 
 sels were evidently contracted, and one of them, further on in 
 the thick part of the body, was evenly dilated to 0'05 of a line. 
 The differences in breadth, which may be successively observed 
 in the same place during life, are again very considerable. A 
 vessel between the axis and the seminal capsule measured in its 
 condition of expansion 0*05 of a line, and contracted to *02 of a 
 line. 
 
 This rhythmical expansion and contraction of the larger ves- 
 sels goes on in somewhat different modes. Frequently one por- 
 tion of a vessel is suddenly distended by the wave propelled by 
 the contraction of that portion which lies immediately behind it, 
 and then collapses again. At other times one part is slowly dis- 
 tended by the blood which streams in gradually, especially out 
 of the smaller vessels, and at last contracts with a jerk, whereby 
 the vessel in consequence of its elongation becomes much bent. 
 
 The independent share of single portions of the vascular 
 system in the centripetal movements of the blood is very clear 
 here as in other parts of the Cephalopoda, e. g. the gills. 
 
 More or less rhythmical and swift contractions are seen to 
 drive the blood from the smallest venous twigs into the larger 
 trunks ; these help it on further either by an immediate contrac- 
 tion, which is a continuation of that of the smaller branches, or 
 only after they are more dilated by the repeated contractions of 
 the latter. That this venous movement is nowise propagated 
 from the arteries, is clear from the circumstance that single 
 
ARGONAUTA ARGO AND THE HECTOCOTYLI. 65 
 
 ramifications often pulsate rapidly, while the neighbouring ones 
 are either still or move at a different pace. These relations are 
 especially recognizable in those ramifications which come off 
 from a transverse branch of the longitudinal trunks, between 
 every pair of suckers, and spread in the membranous fringe 
 connecting these. 
 
 Here, as in many other places in the Cephalopods, one may 
 readily convince oneself of the existence of capillary vessels. 
 
 Concerning the development of the male Argonaut I can state 
 nothing, since I unfortunately obtained no more ova advanced 
 in development, after I had discovered the Hectocotylus to be 
 an arm ; and inasmuch as I had not previously paid sufficient 
 attention to the form of the arms, in the expectation of finding 
 the totally different vermiform embryos described by Madame 
 Power. Indubitably, however, the male embryos are not to be 
 found in especial bunches of ova, but have been frequently 
 seen among the female ones by Kolliker and myself, although 
 from the similarity of their form no further notice has been 
 taken of them. One is the more justified in this supposition, 
 since the sac with the Hectocotylus appears to be relatively 
 smaller the younger the animal, and from its shape might be 
 easily confounded with the yelk-sac. 
 
 In some preserved ova of the Argonaut far advanced in deve- 
 lopment, I believe that I can recognize the arm of the Hectoco- 
 tylus, 
 
 The statements of Madame Power and of Maravigno quoted 
 by Kolliker (/. c. p. 84) contain truth and fiction ; but they may 
 be thus interpreted. What are denominated Hectocotyli three 
 days old are without doubt Hectocotyli ; the description of them 
 which is given, no less than the statement that only two or three 
 are developed in the maternal shell, accords very well with this 
 view. For if we procure Argonauts with advanced ova, in a 
 short time we see the hatched young swim about in innume- 
 rable multitudes. The statement that the seven other arms 
 spring out as buds from the vermiform animal {while it is assu- 
 ming the form of the common Argonaut, leads one almost to 
 believe that Madame Power saw entire male Argonauts with 
 Hectocotylus-arms everted from their sacs in the shell of the 
 female Argonaut. 
 
 SCIEN. MEN. Nat. Hist. VOL. I. PART I. 5 
 
66 MULLER ON THE MALE OF 
 
 If this were demonstrable from the original manuscript, it 
 would afford an important evidence in favour of the immediate 
 transportation of the Hectocotylus from the whole male upon 
 the female Argonaut* 
 
 In the following pages I will bring forward for comparison 
 all that is to be said concerning the two other known kinds of 
 Hectocotylus, for it is precisely the very striking differences and 
 similarities of the three Hectocotyli with one another, that pro- 
 mise in course of time to afford an insight into the meaning of 
 the separate organs and the nature of this singular creature as a 
 whole. 
 
 For this purpose I refer to the description by Kolliker of the 
 Hectocotylus Tremoctopodis, and to that of the Hectocotylus Octo- 
 podis by Cuvier and Verany. Although the identity of the spe- 
 cies of Octopus, in which Cuvier and Verany found their Hecto- 
 cotyliy is not demonstrated, yet the Hectocotyli are so nearly re- 
 lated that they may well be considered together. 
 
 Hectocotylus Octopodis. 
 
 As Kolliker has shown, the Hectocotylus of the Octopus is di- 
 stinguished from that of the Argonaut not only by its greater size, 
 but because at one extremity instead of the filiform appendage 
 there is a vesicle containing a filament ; in other respects the 
 two forms essentially agree. 
 
 Upon comparing the figures of Cuvier and Verany, we find 
 that the " solid cylindrical body " which Cuvier indicates as the 
 origin of the silky thread is the muscular axis ; the supposed 
 nervous threads of Cuvier are the vascular trunks, which in 
 Hectocotylus Argonaut take on a similar appearance in spirit ; 
 the sac (e) filled with the coils of a white thread is the thicker 
 seminal capsule ; the canal (h) is the ductus deferens upon the 
 back ; the " stomach " (d ) corresponds with the pigmented 
 dorsal capsule of Hectocotylus Argonaut. The position of the 
 aperture of this capsule alone differs, since in Hectocotylus Ar- 
 gonautce it remains at the posterior end, while Cuvier has depicted 
 it at the anterior (/). According to this figure and Cuvier's 
 statement that this opening (which he calls a mouth) in the fresh 
 state is slit-like and leads into the pigmented capsule, as well as 
 from the analogy of Hectocotylus Argonauts, I cannot agree 
 
ARGONAUTA ARGO AND THE HECTOCOTYLI. 07 
 
 with Kolliker (pp. 79 & 80) that this aperture belongs to the 
 seminal capsule. Whether a second aperture for this exists at 
 the anterior end is not certainly determined by Cuvier himself, 
 and he does not state that Laurillard had seen the seinen poured 
 out anteriorly. The connexion which, according to Cuvier, exists 
 between the thread (i) everted from the terminal vesicle, on the 
 one hand with the axis of the body, and on the other with the 
 canal (ti), which, coming from the seminal capsule, is evidently 
 analogous to the ductus deferens in the Argonaut, is singular. 
 
 If with Kolliker we may be permitted here to suppose an 
 error on the part of Cuvier, who only examined spirit speci- 
 mens, I should imagine, keeping in view the fact that Verany 
 found a filament with a free and pointed end in the terminal 
 vesicle of the Octopus, that the latter was overlooked by Cuvier. 
 If this be the case, the analogy between the filament exserted 
 from its vesicle and the filamentous appendage (penis) of Hecto- 
 cotylus Argonauta becomes striking. 
 
 It would then require to be made out whether and how this 
 appendage makes its exit from its vesicle, and we might con- 
 ceive similar relations to those which I shall subsequently show 
 obtain in Hectocotylus Tremoctopodis. In the latter case the 
 presumed error of Cuvier would be easily explicable. The above- 
 mentioned differences in the position of the pigmented sac 
 might also be connected with the difference in the position of 
 the appendage, since in Hectocotylus Octopodis the supposed 
 appendage is perhaps never meant to pass into that pigmented 
 capsule as in Hectocotylus Argonauts. 
 
 From the structure of the Hectocotylus Octopodis, especially 
 the presence of the silky thread in the capsule, e, and the asser- 
 tion of Dujardin (Helminthes, p. 131) that the white thread 
 consists of spermatozoa, the male nature of this Hectocotylus also 
 may be concluded. 
 
 Its development is probably quite similar to that of the Hec- 
 tocotylus of the Argonaut. 
 
 Verany and Filippi (see above) have already proved that the 
 Hectocotylus of the Octopod arises as one of its arms. Verany 
 has observed in the same place a sac, which, according to the 
 figure in which chromatophora are indicated, appears rather to 
 be analogous to the sac of the male Argonaut than to the 
 
 5* 
 
68 MULLER OX THE MALE OF 
 
 vesicle which otherwise terminates the Hectocotylus Octopodis. 
 The pigmented capsule upon the back of the latter again is evi- 
 dence of a process of eversion similar to that of the Argonaut ; 
 and in the specimen of Octopus, which M. Verany had the good- 
 ness to show me, the pigmented spot upon the back of the 
 Hectocotylus-arm appeared very similar, if I do not err, to that 
 upon the back of the Hectocotylus-arm of the Argonaut when 
 just everted from its sac. Here also then the eversion of the 
 Hectocotylus from its sac precedes its separation. Whether the 
 pigmented capsule is already developed in one of Verany's spe- 
 cimens I know not. It is interesting that Cuvier describes one 
 of his Hectocotyli as the arm of the Octopus. Four out of five 
 individuals were found in the mantle of the Octopod ; " the fifth 
 had attached itself to one arm of the Poulpe, and had changed 
 it into a kind of sac in which it had imbedded its head, whilst the 
 rest of the body remained free externally (p. 150) ; " and " it has 
 almost destroyed the arm, and appears to replace it so com- 
 pletely that at first it might be taken for the arm itself " (p. 149), 
 It is hardly to be doubted that the animal " qu'un parasite devore" 
 was a male Octopus, which carried a Hectocotylus newly freed 
 from its sac, but not yet separated. The last link of the series 
 finally is formed by that Octopus, in which Verany found merely 
 a short stump in the place of the Hectocotylus-arm, which in all 
 probability had already fallen off. 
 
 Considering the general resemblance of the Hectocotyli of the 
 Argonaut and of the Octopus, it is very remarkable, that, accord- 
 ing to Verany, in all cases the third arm of the right side is the 
 abnormally developed one in Octopus, whilst in the Argonauts 
 it always is the third arm of the left side. Cuvier does not 
 state in the place of what arm his Hectocotylus was fixed. 
 
 It is much to be regretted that Cuvier has given no informa- 
 tion as to the sexual organs of the Octopods which carried the 
 Hectocotyli in their mantle or as an arm, and it is the more de- 
 sirable that such Octopods should be closely examined, since 
 their more considerable size will without doubt allow a more 
 easy and better determination of many points than the small 
 Argonauts permit. 
 
ARGONAUTA ARGO AND THE HECTOCOTYL1. 69 
 
 Hectocotylus Tremoctopodis. 
 
 The third kind, the Hectocotylus Tremoctopodis, is interme- 
 diate in size between the two others ; in form, however, it differs 
 far more from the Hectocotylus of the Argonaut than from that 
 of the Octopus. Nothing is known of its development. 
 
 However, besides the structure of the muscular tube of the 
 body already pointed out by Kolliker, that of the suckers, and 
 the presence of genuine chromatophora, we have one very im- 
 portant point of resemblance with the Hectocotylus Argonauta 
 in the presence of a longitudinal series of ganglia. 
 
 This ganglionic chain, which has already been recognized by 
 Von Siebold, passes from the anterior end of the Hectocotylus 
 to the commencement of the capsule in the abdomen. The 
 single ganglia are so disposed that one lies upon each of the 
 alternating suckers ; they are thence closely appressed. If we 
 make a longitudinal section, not perpendicularly between the 
 suckers, but horizontally, we obtain precisely the view given by 
 Kolliker, pi. 2. fig. 14. It is therefore obvious that the co- 
 nical masses of granular substance described by him, at p. 74, 
 were these ganglia. 
 
 The doubts as to the presence of any intestine expressed by 
 Kolliker are quite just in this case. The opening which he 
 also gives as doubtful, at the anterior extremity of the body 
 somewhat towards the back, was perhaps only the end of the 
 axis whose already attenuated tube here terminates the inner 
 layers contributing to form a blind end round the last ganglion, 
 while the outer layers united with the skin form a more or less 
 distinct knob*. 
 
 If in many cases an opening is actually present, this would 
 indicate even more than the mode of termination which has 
 been described, and which agrees with that of the thick end of 
 the Hectocotylus Argonaut &, that supposing the Hectocotylus of 
 the Tremoctopus to be developed as an arm like the others, this 
 is its attached end. 
 
 The structure of the opposite end renders this conclusion 
 
 * Von Siebold also has concluded from the want of such an aperture that 
 there is no digestive organ in Hectocotylus Tremoctopodis, and Cuvier affirms 
 that in Hectocotyliis Octopodis the axis has no opening anteriorly. 
 
70 MULLER ON THE MALE OP 
 
 probable ; the ovate or pyriform capsule in the abdomen being 
 similar to that which in Octopus is certainly placed at the free 
 end of the Hectocotylus-arm. 
 
 Besides, both in form and position that abdominal capsule is 
 analogous to the membranous lobe on the appendage of Hecto- 
 cotylus Argonautce. 
 
 Among eighteen Hectocotyli of Tremoctopus, twelve had the 
 abdomen constructed as Kolliker has described it. In six, how- 
 ever, the capsule of the abdomen had a cleft upon its dorsal side ; 
 this commenced close behind the last sucker of the left side (the 
 suckers being supposed to be below and the capsule behind), 
 and extended somewhat obliquely as far as the commencement of 
 the delicate process into which the capsule is prolonged ; the 
 latter lay consequently wide open, and it could readily be seen 
 that it was empty ; that is, that it contained neither the convo- 
 lutions of the seminal capsule nor the ductus deferens, which 
 in other cases are found in the closed capsule*. Upon careful 
 examination, however, the cleft is, even in all ordinary Hecto- 
 cotyli, to be seen as a streak occupying the direction indicated. 
 There is a ridge upon the right side ; pale, more or less closely 
 adherent, and capable of being raised. It can be observed then 
 that the subjacent layer, upon the left side, passes for a cer- 
 tain distance under the other, and appears to be as it were rolled 
 up at its anterior end. 
 
 In Hectocotylus Tremoctopodis this cleft then always exists, 
 and it would be interesting to know whether it also occurs in 
 the capsule of Hectocotylus Octopodis. 
 
 When the cleft is open and the capsule is empty and relaxed, 
 it has a considerable resemblance in external character to the 
 membranous lobe of Hectocotylus Argonautae, which also at 
 times forms a deep pit. Both organs exhibit a lively undulatory 
 movement. 
 
 In order to comprehend more exactly the relative position of 
 the capsule, it is previously necessary to show that the penis of 
 
 * I presume, that at least in most cases the capsule has been burst after the 
 Heclocotyli were taken, by contact with fresh water or the like. In three Hec- 
 tocotyli of the ordinary form which I had thrown into a dilute solution of 
 chromic acid, I also found after a few days the capsule open and the contents 
 fallen out. 
 
ARGONAUTA ARGO AND THE HECTOCOTYLI. 71 
 
 the Hectocolylus Tremoctopodis is analogous to the filiform ap- 
 pendage of Hectocotylus Argonaut. 
 
 Of the six specimens in which the cleft in the capsule was 
 open, three were particularly distinguished by having no penis 
 visible externally. It was not torn off, as might have been con- 
 cluded from the absence of the opening out of which it generally 
 passes * ; but it lay spirally coiled up under the skin inferiorly 
 behind the last suckers, and, indeed, more towards the right 
 side. It was very short, but relatively thick. Here then it was 
 clearly evident that the penis is the immediate continuation of 
 the muscular axis, which could not be so well demonstrated in 
 specimens with a long free penis. Close behind the last suckers, 
 the end of the thick part of the axis, which contains the last 
 ganglion, lies in such a manner in the lower wall of the capsule, 
 that it can be seen through the dorsal cleft above mentioned as 
 a knob somewhat projecting from the inner surface of the cap- 
 sule. From this the muscular tube bends down to the lower 
 side of the Hectocotylus and forms the penis, which here lies 
 coiled up under the skin, instead of as usual passing forward 
 and becoming free in the neighbourhood of the third to the fifth 
 sucker. 
 
 Where the axis bends down, the longitudinal vascular trunks 
 pass into the penis f Immediately beyond this flexure the. 
 ductus deferens, generally convoluted, comes from the left side 
 to the anterior side of the penis into which it penetrates. The 
 larger convolutions which this duct frequently makes at the 
 base of the penis produce the transverse ridge, which may be 
 frequently observed in many Hectocotyli between the body and 
 the capsule upon the lower side. 
 
 If now we consider the place of the cleft capsule, keeping in 
 mind this relation of the penis to the axis, its position upon the 
 back of the axis (where the thicker part passes into the thinner) 
 is quite analogous to that of the membranous lobe in Hectoco- 
 tylus Argonautce. 
 
 * In one specimen the semicircular edge which usually surrounds the aper- 
 ture behind was faintly indicated, perhaps in preparation for the subsequent 
 exit. 
 
 f Whether at an earlier period the contents of the axis also are continued 
 into the penis, I cannot decidedly say. 
 
72 MULLER ON THE MALE OF 
 
 If then the abdominal capsule of Hectocotylus Tremoctopodis 
 is analogous with this lobe, and perhaps also with the terminal 
 vesicle of Hectocotylus Octopodis, we must give up its supposed 
 analogy with the pigmented capsule of the two other Hecto- 
 cotyli; and the Hectocotylus Tremoctopodis seems to possess 
 nothing comparable therewith. 
 
 On the other hand, the presence of a free penis by no means 
 constitutes an absolute difference from the other Hectocotyli. It 
 is its position chiefly which distinguishes it from the appendage 
 of Hectocotylus Argonautae, and the circumstance that the ductus 
 deferens lies in its interior, whilst in the latter it is only attached 
 externally to the prolongation of the axis. If it were certain 
 that the filament which we find in the terminal vesicle of Hecto- 
 cotylus Octopodis had the same signification, and is not a mere 
 seminal tube, the analogy of the three Hectocotyli in this point 
 would be complete. 
 
 In the other portions of the sexual apparatus, the testis and 
 the ductus deferens, such an agreement cannot at present be 
 demonstrated. 
 
 Kolliker has named ( testis ' a vesicle which generally com- 
 pletely fills the abdominal capsule. The cleft outer capsule 
 readily separates again into two layers, the outer of which is 
 similar to the general cutaneous investment: under the epithe- 
 lium there is a fibrous network with numerous vessels, whose 
 capillary loops may be seen in the delicate terminal prolonga- 
 tion. The second layer consists, like the subcutaneous tissue of 
 the back, of muscular bundles, which especially affect a longi- 
 tudinal arrangement. Upon the inner surface it supports a layer 
 of delicate polygonal cells. Below this again comes the so-called 
 sac of the testis, which may be easily separated. Its wall has a 
 peculiar checkered (carrirtes) appearance ; t\vo layers of fibres 
 are visible, which cover one another very regularly like the 
 fibres of a tissue, at right angles, or often at somewhat oblique 
 angles. The fibres are when isolated somewhat rigid, but often- 
 times not dissimilar to muscular fibres. Elsewhere, however, 
 they can be hardly separated at all, and in many places almost 
 structureless layers occur. 
 
 In the interior of this vesicle there was always contained the 
 thread described by Kolliker, which consists almost entirely 
 
ARGOXAUTA ARGO AND THE IIECTOCOTYLI. 7-3 
 
 of perfect spermatozoa. In this case a special investment is fre- 
 quently not to be discovered, as Kolliker and Von Siebold (VergL 
 Anat. p. 411) state; in a few instances, however, the greater 
 part of the thread was surrounded by a distinct structureless 
 membrane. 
 
 Its existence was clear in places where it stretched over gaps 
 in the contents, or where it was quite empty, and also in places 
 where it was torn, and the masses of spermatozoa had swelled 
 up and made their way out. Whether this investment is a true 
 membrane which subsequently disappears, or whether more 
 probably it is rather an accidentally deposited homogeneous mass, 
 I will not attempt to decide ; only it is to be noted that this in- 
 vestment was not to be found in a few other portions of the same 
 seminal cylinder. 
 
 The one end of this filiform seminal mass is connected with 
 the bulb which forms the commencement of the ductus deferens 
 (ductus ejaculatorius, V. Siebold) described by Kolliker. One 
 part of it lies coiled up with the seminal cylinder in the checkered 
 vesicle, the other part stretches on into the penis. 
 
 This peculiar ductus deferens* appears to consist of a sub- 
 stance essentially identical throughout, but varying very greatly 
 in consistence and form in different localities. It is a yellowish 
 or colourless^ sometimes tough, sometimes more brittle, but 
 elastic mass, which frequently, e. g. in the interior of the bulb, 
 is tolerably soft, but at other places is of almost horny hard- 
 ness and friability. Histologically, it appears sometimes struc- 
 tureless, sometimes marked very beautifully with parallel stria- 
 tions. The striae are either immeasurably close or 0'004 (fre- 
 quently 0'001-'002) of a line apart, and exhibit transitions from 
 the most extreme delicacy to very marked lines. 
 
 They have the greatest similarity with those which we see in 
 the wall of the Echinococcus vesicles. The structureless mass 
 appears to pass into more slightly or more strongly marked 
 layers which determine the partly longitudinal, partly transverse 
 striation. This often takes on very strange forms when the 
 parts are torn, doubtless in consequence of the folding and tear- 
 
 * I retain this term, although the part does not seem to he quite analogous 
 to the organ so named in H, Aryonauta. 
 
74 MtJLLER ON THE MALE OF 
 
 ing. The substance is little altered by a diluted solution of 
 caustic soda. 
 
 The innermost coat of the ductus deferens is generally formed 
 by a layer which strongly refracts light, and when it is stretched 
 looks like a tubular brittle glassy membrane. 
 
 Elsewhere when collapsed it has the appearance of a longitudi- 
 nally fibrous cord,which is easily torn transversely into fragments, 
 and only the local dilatations (for example from 0'02 of a line in 
 diameter to quite smooth clear vesicles of 0-2 of a line in diameter) 
 show its tubular character. One portion is frequently invagi- 
 nated for a certain distance in a funnel-shaped expanded portion 
 behind it, whereby a swelling is produced. In other places the 
 innermost layer forms the spiral band mentioned by Kolliker. 
 This exhibits considerable elasticity, and its coils are often 
 very close, often far separated, which depends upon the form 
 of the penis. The band has sometimes the appearance of a 
 spirally cut delicate tube, sometimes that of a cylinder, like the 
 snake-toys which are cut out of horn. 
 
 Next to this innermost layer the mass of the ductus deferens 
 appears to be longitudinally striated to an irregular extent. Ex- 
 ternally again it becomes circularly striated, and not unfre- 
 quently some layers appear to be more sharply distinguished 
 from the rest. In the midst some portion will frequently be 
 found wholly structureless, and quite external to the ductus 
 deferens ; a strongly marked layer has again all the characters of 
 a so-called vitreous membrane. 
 
 In the penis the whole ductus deferens, without reference 
 to its contained spiral band, sometimes forms spiral coils of 
 much greater extent, in which the outer layers of the penis take 
 but little part. 
 
 Many modifications of the ductus deferens occur which appear 
 to indicate different stages of development. Instead of the 
 usually tolerably solid enlargement at its commencement (Kol- 
 liker, pi. 2. fig. 11 d), there exists at times a somewhat large 
 pyriform body which attains a few lines in length, and the larger 
 it is so much the softer are its contents. In its axis, however, one 
 can already distinguish the commencement of the inner denser 
 tube, which further on in the ductus deferens incloses or forms 
 the spiral band. 
 
ARGONAUTA ARGO AND THE HECTOCOTYLT. ?5 
 
 In one of the specimens without any externally visible penis 
 there projected from the cleft in the back a transparent, pointed, 
 ovate vesicle of a few lines in length, which contained merely 
 a fluid, and at its fixed end was drawn out into a more delicate 
 fine tube of about the same length. The latter appeared 
 when the vesicle, in consequence of being frequently touched, 
 detached itself, and was evidently formed analogous to the 
 ductus deferens ; it consisted of a longitudinally striated cord 
 (i.e. perhaps a folded tube) and an external, distant, structureless, 
 partially laminated sheath. The larger vesicle therefore may per- 
 haps be considered as an earlier form of development of the bulb, 
 with which the vas deferens generally begins. Other changes in 
 the latter and in the penis appear to belong to a later period. In 
 two Hectocotyli which were met with in copulation upon female 
 Tremoctopoda (vide infra), the abdominal capsule was also open 
 and empty, probably in consequence of long lying in water. 
 The penis, however, with the external part of the ductus deferens 
 plainly visible in it, was distinguished onboth occasions by a length 
 of an inch and a half. It passed out of the skin, not in the middle 
 line, but nearer to the right-hand series of suckers, and close 
 to the penultimate pair, which plainly arose from its being torn. 
 Its outermost third appeared to be similar to the whole free part 
 of the penis in other cases ; the two upper thirds were thinner, 
 as if pulled out longitudinally. After the skin was taken away 
 from the place of exit of the penis as far as the abdominal cap- 
 sule, the portion of the penis lying below it was seen to pass 
 below the axis obliquely towards the last sucker of the left side, 
 and there cease. This inner part of the penis formed a fusi- 
 form enlargement, which appeared to be hollow. The outer- 
 most layers of the penis passed into the surrounding fibrous 
 tissue, but the connexion with the axis was no longer recogni- 
 zable. In all probability these changes of form of the penis and 
 ductus deferens are connected with the function of copulation, 
 and a third Hectocotylus, in which the outermost portion of the 
 penis was plainly torn off, but the inner end had the same rela- 
 tion as in the other two, had probably already performed this 
 act. Its abdominal capsule also was open and empty. The 
 eversion of the ductus deferens for the purpose of ejaculation, 
 indicated by Von Siebold (/. c. p. 411), appears to take place, 
 
?6 MULLER ON THE MALE OF 
 
 and indeed in a peculiar manner, which reminds one of the 
 process of eversion of the spermatophora of other Cepha- 
 lopoda described by Milne-Edwards (Annales d. Sc. Naturelles* 
 1842). 
 
 From the preceding facts I will merely draw the conclusion, 
 that the sexual organs in Hectocotylus Tremoctopodis are not only 
 more complicated than in Hectocotylus Argonaut a, but that dif- 
 ferent stages in their development occur, although the Hectoco- 
 tylus possesses in general the same form as that with which we 
 are already acquainted. Our knowledge of this Hectocotylus is 
 too imperfect to enable us to give a general interpretation of the 
 generative organs. But its structure and the analogy with the 
 Hectocotylus of the Argonaut lead to the supposition that the 
 vesicle which contains the seminal coil is not the testis, but a 
 seminal receptacle, although the mode in which the semen makes 
 its way, and the place of its origin are less demonstrable than in 
 the Hectocotylus of the Argonaut. 
 
 Next to the generative apparatus, the most striking features 
 in Hectocotylus Tremoctopodis are the numerous villi on each 
 side of the back, which Kolliker has with great probability 
 called gills *. 
 
 In the living Hectocotylus the single villi are contractile, ap- 
 parently in consequence of the fibres which form a meshwork 
 in their interior. Independently of this movement of their sub- 
 stance, a considerable rhythmical contraction may be observed 
 in the efferent (venous) part of the very rich and frequently 
 anastomosing vascular network which lies in each villus, and 
 which passes from the finer to the coarser vessels, as was stated 
 above to be the case in the Hectocotylus Argonautce and in the 
 Cephalopoda in general. In one instance there were twenty-two 
 contractions in ten minutes. 
 
 Since these branchial villi might occur in different individuals 
 in different degrees of contraction, the determination of their 
 size in different individuals appeared to be a matter of some 
 interest. For this purpose the largest group of villi in each of 
 several specimens preserved in spirit was selected. When they 
 were very much developed, their length was about 0-6-1-2 of a 
 
 * Do these in any way subs.erve nutrition within the mantle of the female? 
 (see Von Sicbohl, /. c. p. 389). 
 
ARGOXAUTA ARGO AND THE HECTOCOTYLI. 77 
 
 line. The smallest were not much shorter, and some were 
 longer. The breadth in the middle of the villi was generally 
 0-15, hardly under 0'12, but as much as 0'22 of a line. These 
 were Hectocotyli with a freely projecting penis. 
 
 In two others, on the other hand, whose penis was hidden, 
 the length of the villi was but rarely over 0*6-0*7 of a line, and 
 the most were shorter. The breadth was at the base rarely more 
 than 0'12 of a line, and diminished rapidly to 0*06 or 0'04 of a 
 line. The villi namely, had here the form of a rapidly dimi- 
 nishing and pointed cone, whilst in specimens with well- deve- 
 loped gills the diameter of the gills in the outer half surpassed 
 at times that of the base, and the end was more rounded than 
 pointed. 
 
 Since it may be assumed that Hectocotyli with larger gills have 
 in general progressed further in their development than those 
 with smaller ones, we have here a further evidence that the penis 
 rolled up under the skin of the latter is a younger stage of de- 
 velopment than the common form of the free penis. 
 
 The Hectocotylus of the Tremoctopus, then, is very strongly 
 distinguished from the two others by the want of a pigmented 
 dorsal capsule ; by the position of the seminal coil in the cap- 
 sule at the end of the body, and the peculiar structure of the 
 ductus deferens ; lastly, by the presence of gills : and, indeed, 
 from the great discrepancies which exist among the Hecto- 
 cotylus-bearing males of Cephalopods among nearly allied spe- 
 cies, we should be prepared for thorough differences among 
 themselves. 
 
 Upon the other hand, the analogy of the Hectocotylus of the 
 Tremoctopus with the others in all essential points is so great, 
 that although there is a complete want of all direct observations, 
 we must assume it to have a similar origin, and that one day an 
 entire male Tremoctopus belonging to this Hectocotylus will be 
 discovered, the exact investigation of which will doubtless be 
 still more interesting than in the Argonaut. However that may 
 be, all three Hectocotyli must be kept in mind in attempting to 
 determine the nature of the Hectocotyli in general. 
 
78 MULLER ON THE MALE OF 
 
 Nature of the Hectocotyli. 
 
 With regard to this problem, we must consider, first, their 
 relation to the animal which lodges them in their free condition, 
 and, secondly, to that as whose arm they are developed. 
 
 The main point as respects the former relation, which Kolliker 
 first demonstrated for the Hectocotyli, may be safely assumed 
 to be that each of the three forms of Hectocotylus, considered 
 as one with the animal upon which it is developed *, forms the 
 male factor with respect to a particular kind of female Cepha- 
 lopod; Argonauta, Tremoctopus and Octopus granulosus, Lamarck, 
 O. Carena f, Verany. The evidence of this consists in the fol- 
 lowing facts : 
 
 1. No other males of the Cephalopoda mentioned are known. 
 All Argonauts { of the ordinary form with velate arms, and all 
 individuals of Tremoctopus which have been dissected, were 
 females with ova. To the Argonauts enumerated by Kolliker I 
 can add fifty others of every size, and to the thirteen individuals 
 of Tremoctopus, thirty which I have examined with reference to 
 this matter. As has been said, nothing is known respecting the 
 Octopus. 
 
 2. Most of the free Hectocotyli carried semen demon strably ; 
 and it is very probable that the others had done so. To the 
 fifteen Hectocotyli Tremoctopodis fourteen others may be added 
 in which this was certain, whilst in four the demonstration failed 
 on account of the emptiness of the capsule. In Cuvier's Hec- 
 tocotylus Octopodis Dujardin found spermatozoa. To the six 
 Hectocotyli Argonautce enumerated by Kolliker, I can add thir- 
 teen which all carried the white sac under the pigmented dorsal 
 capsule, and as often as this was opened it was found to con- 
 tain spermatozoa. To these free Hectocotyli are to be added 
 the Argonauts which carried a Hectocotylus-arm inclosed in its 
 sac. All the specimens, which were carefully examined, contained 
 semen either in the sac of the Hectocotylus-arm or in the testis. 
 
 Respecting these animals, indeed, doubts might be raised as 
 to the identity of the species with the common Argonaut, on 
 
 * Hectocotylus Tremoctopodis questionably, 
 f If these be different, there will be four species. 
 
 J Verany (p. 54) cites a solitary statement of Leach that he had found a 
 male Argonaut. 
 
ARGONAUTA ARGO AND THE IIECTOCOTYLI. 79 
 
 account of the want of both the expanded arms and the shell. 
 But, in the first place, the similarity of the Hectocotylus-arm 
 with the free Hectocotylus speaks for that identity. Next, the 
 mode in which they occur : during a few days only did I obtain 
 the animals with the Hectocotylus-arm and Argonauts of the 
 ordinary kind in any quantity together. The latter were partly 
 larger ones with shells, partly also not more than 2-4 lines long, 
 and these, like the males, had no shell, at least as I obtained 
 them, while the expanded arms were already easily recognizable. 
 The colour and remaining form of the body were, however, in 
 such close agreement with those of the male animals *, that the 
 presence of the expanded arms and afterwards of the shell must 
 be considered not to be specific, but to be sexual differences. It 
 is perhaps not without importance, that these vela with a kind 
 of mesentery on the twisted axis of the arms occur in females 
 of that species whose males carry an arm so excessively deve- 
 loped, which however belongs to a different pair from the vela 
 of the female. The same probably holds good of Tremoctopus ; 
 for in this, as I shall elsewhere show, the two upper arms have 
 not the shape which is commonly figured, but form, when, as 
 rarely happens, they are well preserved, elongated lobes, which 
 excite as much surprise by their enormous size as by the extra- 
 ordinary magnificence of their coloration. 
 
 It may be expected that the male Tremoctopus may have such 
 a structure, as to have been described as some other kind of 
 Octopus. Since Cuvier says nothing of any difference in those 
 Octopods which lodged the Hectocotyli from the other which 
 carried the Hectocotylus as an arm, it seems that the male, as 
 which the latter no less than Verany's specimen of Octopus Ca- 
 rena must be regarded, in this case is not strikingly different from 
 the female. 
 
 3. The anatomical agreement of the suckers, &c. of each Hec- 
 tocotylus with those of the Cephalopod female upon which it 
 occurs, has been especially made out by Kolliker. 
 
 4. In like manner the exclusive association of each Hectoco- 
 tylus with its kind of female only. Up to the present time free 
 Hectocotyli have only been found in the society of female Cepha- 
 
 * Even the bundles of hairs described by Kolliker (Entwickelungsgeschichte 
 d. Cephalopoderi) were present as in the females of the size of a hazel-nut. In 
 larger specimens I no longer found them. 
 
80 MULLER ON THE MALE OF 
 
 lopoda, and indeed, as Kolliker observes, only upon females with 
 ripe ova. I have myself found the free Hectocotylus Argonauts 
 only upon the inner surface of the shell, or upon the ova, or 
 fixed or creeping upon the animal itself, and I can affirm that 
 among the many Argonauts, less than a nut in size, which I 
 have examined, I never found a Hectocotylus. The Hectocotyli 
 of the Tremoctopus were almost all fixed in the mantle-cavity ; 
 a few crept about in its vicinity externally, or lay at the bottom 
 of the vessel in which the Tremoctopus was contained ; since, 
 as Kolliker has stated, they usually leave the dead animal. 
 
 5. Direct testimony that the Hectocotyli play the part of males 
 to their female Cephalopoda is afforded by two observations of 
 a perfect copulation in Tremoctopus. 
 
 Upon the 2nd of August two large specimens of Tremoc- 
 topus were brought to me at the same time, each of which carried 
 in its mantle-cavity a Hectocotylus^ fixed as usual in the neigh- 
 bourhood of the gills. Upon pouring water on them, it was seen 
 that the penis of each \vas inserted far into the opening of the 
 right oviduct. Both of the Hectocotyli moved vivaciously, and 
 appeared to be very angry that their endeavours were disturbed. 
 Since it was late in the evening I was obliged to defer further 
 examination until the following morning, when I found both in 
 situ, but dead. Both Hectocotyli were distinguished by the 
 length of the penis ; on endeavouring to draw it out of the ovi- 
 duct it was* held pretty fast, and if let go was retracted again for 
 a certain distance ; one might so allow half an inch of the penis 
 to glide in and out. This resulted from a very elastic filament, 
 which, from the point of the penis, projected in deeper ; it could 
 be drawn out for an inch from the opening of the oviduct with 
 the penis, and then when it finally gave way it slipped back 
 again. In both cases this thread did not exactly enter at the 
 point of the penis, but somewhat behind ; and then in its further 
 course it could be clearly identified as the inner part of the for- 
 merly-described ductus deferens. 
 
 The right oviduct of the Tremoctopus possessed, besides the 
 chambered gland, two dilatations whose walls were greatly soft- 
 ened. The external enlargement was little larger than upon the 
 left side, and contained, together with mucus, merely a portion 
 of the thread torn off from the penis, which has been mentioned. 
 The second larger expansion contained the very singularly con- 
 
ARGONAUTA ARGO AND THE HECTOCOTYLI. 81 
 
 structed continuation of this ; I will only remark that there hung 
 therein a solid white reniform body of some lines in diameter 
 which consisted wholly of spermatozoa. These were quite 
 similar to those which are usually found in Hectocotylus Tremoc- 
 topodis, and it is therefore unquestionable that these Hectocotyli 
 also serve to fecundate the female Tremoctopoda. 
 
 The observation of peculiarly-formed masses of spermatozoa 
 far back in the compartments of the oviducal gland itself, was 
 repeated in many specimens of Tremoctopus, and it seems al- 
 most as though this gland had at least in part the function of 
 a spermatheca ; though indeed its relations in other Octopods do 
 not well agree with this view. On the other side of the gland 
 1 found no semen, neither in the two copulating Tremoctopoda 
 nor in others ; but I will so much the less question the possi- 
 bility of its penetration as far as the ovarian capsule, as the por- 
 tion of the oviduct between the gland and the ovary is remark- 
 able for its conspicuous ciliary epithelium. A similar epithelium 
 invests also the folds of the ovarian capsule itself which converge 
 towards the internal aperture of the oviduct ; it is found there 
 over a considerable space, and finally extends through the so- 
 called water-canal described by Delle Chiaje and Krohn in 
 Tremoctopus and Eledone, which reaches from the posterior side 
 of the ovarian capsule towards the lateral compartment. 
 
 For Argonauta I can bring forward no such complete obser- 
 vation, yet the copulation and fecundation by the penetration 
 of the appendage of Hectocotylus Argonauta into the female 
 sexual aperture become very probable from the following facts. 
 
 The ovarian capsule of an adult Argonaut contained a filiform 
 body, which, from its form, from the lobe at the thicker end, 
 and from its minuter structure, was certainly the torn- off append- 
 age of a Hectocotylus Argonaut ce. Attached to it were very diffuse 
 masses of spermatozoa in lively motion. In another very large 
 Argonaut I had sought in vain for Hectocotyli. After cutting 
 up the intestines, and especially the generative organs in many 
 directions, I found in the water used for washing the parts, three 
 filaments, which were the appendages of so many Hectocotyli. 
 
 Functionally, then, the appendage of Hectocotylus Argonauta 
 is to be compared to the penis of H. Tremoctopodis, although 
 perhaps the appendage is not always intended to reach the ova- 
 
 SCIEN. MEM. Nat. Hist. VOL. I. PART I. 6 
 
82 AHJLLER ON THE MALE OF 
 
 rian capsule, and may have been a result of some accident to the 
 Hectocotylus. 
 
 The state of polygamy in which many females of these Cepha- 
 lopods live is worthy of remark. Cuvier (Laurillard) found three 
 Hectocotyli in the mantle of an Octopus ; Kolliker, among twelve 
 Hectocotyli of the Tremoctopus, once found three together, and 
 twice, two ; Von Siebold found among three, two together ; I 
 among eighteen found four together once, and three times, two 
 upon one specimen. I also met with two Hectocotyli upon one 
 Argonaut, twice. 
 
 Since it is improbable that the Hectocotyli can pass from one 
 female to another, either the number of the males must be 
 greater than that of the females, or many of the latter must alto- 
 gether despair of the society of the former. On the other hand, 
 it seems that the many Hectocotyli for one female are OVK CLTTO- 
 (frcaXiot, as Homer says of the evval aOavdrcov. In the oviduct 
 of one Tremoctopm were found two distinct, but for the rest 
 almost identical seminal masses, each with its appended tubular 
 filament, and many such fragments appeared to indicate some- 
 thing more than bigamy. 
 
 This is perhaps connected with the manner in which at least 
 a portion of the Cephalopoda here referred to lay their eggs. 
 The ova of Tremoctopus and Argonaut a are, it is well known, 
 found in groups, each of which is attached to a delicate stalk. 
 These stalks are in the Argonaut fastened to the convoluted por- 
 tion of the shell ; in Tremoctopus to a principal stem some lines 
 thick. The ova of each such single group are as a rule at about 
 the same stage of development ; whilst the different groups vary 
 so greatly, that in the larger bunches we frequently meet fresh- 
 laid ova in company with perfect embryos. In this case a re- 
 gular progression may frequently be detected, so that develop- 
 ment gradually advances from one end to the other of the whole 
 bunch. In one bunch of ova of Tremoctopus there was further- 
 more this distinction between the two ends of the principal 
 stem : that the end which carried the most fully-developed em- 
 bryos had a brownish, wrinkled, old appearance ; while that in 
 which the ova were undeveloped was clearer, smoother, softer, 
 and fresh-looking. Between the two were transition-states. 
 The size of each group which has a distinct thinner stalk answers 
 
ARGONAUTA ARGO AND THE HECTOCOTYLI. 83 
 
 pretty closely to the quantity of ova which we often find in Trem- 
 octopus in a dilatation of the oviduct, which, on the outer side, 
 immediately follows the gland. The ova which we find in the 
 part of the oviduct before the gland, as well as in Argonauta in 
 the beginning of the oviduct, are as yet only provided with their 
 separate proper stalks, which are delicate, but already somewhat 
 long ; these become united in the outer part of the oviduct into 
 a group with a common stalk, and thence they probably remain 
 here for a considerable period. It may therefore well be, that 
 the different groups of a large bunch of eggs are attached at dif- 
 ferent times, and although the duration of the intervals is wholly 
 unknown, it may be imagined to be not very small, and perhaps 
 too considerable to allow of the fecundation of all the ova by a 
 single previous copulation. Such ova belonging to different 
 periods might be fecundated by many Hectocotyli at different 
 times. 
 
 Inasmuch as it has been said that the Argonaut is hermaphro- 
 dite, I beg expressly to observe that nothing which I have ever 
 noticed favours this conclusion. In the male specimens the 
 testis lay where otherwise the ovary would be found, and of the 
 latter there was no trace ; whilst in a female of 3 lines long it 
 was already very perceptible, and characterized microscopically 
 by ova of 0-02 of a line in diameter. Besides, the want of the 
 velum upon the arms of the Hectocotylus-bearers shows that 
 these are quite separate individuals from the females. 
 
 If now with regard to two kinds of Hectocotylus the anatomical 
 fact is established, that they are developed as arms of perfect 
 Cephalopods, and also that all three Hectocotyli very frequently 
 occur isolated, there is a question which promises to be one of a 
 more general interest, viz. What is the relation of the free Hec- 
 tocotylus to the animal from which it has detached itself ? 
 
 1. That the Hectocotylus stands still less in the relation of a 
 parasite (Cuvier) to the animal as whose arm it is developed, 
 than to that in whose mantle it resides, is clear. I will only 
 call to mind, how from the very first all observers have brought 
 forward the striking similarity to a Cephalopod-arm ; they have 
 not, however, come to the readiest conclusion, that it is such an 
 arm, without many deviations. 
 
 2. That Madame Power also wrongly imagined the Hectoco- 
 
 6* 
 
84 MULLER ON THE MALE OF 
 
 tylus Argonauts to be a vermiform embryo of the common Argo- 
 nauta (vide supra) has been already shown by Kolliker. 
 
 3. Kolliker brought forward formerly the view that the Hec- 
 tocotyli as male individuals are the independent equivalents of 
 the female Cephalopods. According to the present state of 
 knowledge, this view can be tenable only under two suppositions. 
 Either, one must assume an alternation of generations in its 
 wider sense between the Hectocotylus and its previous supporter ; 
 or, after the separation of the Hectocotylus from the rest of the 
 body, it must be regarded as the representative of the individu- 
 ality, having thrown off the remainder as so much no longer 
 useful ballast. 
 
 Against the former view of a kind of alternation of genera- 
 tions however, too many objections at once arise ; among others, 
 the development in the place of one of the eight typical arms ; 
 the imperfect organization as regards the other generations ; 
 further, that the alternation would take place merely in the 
 males ; whilst the females of Argonaut a and Tremoctopus are 
 known to lay eggs from which individuals similar to them pro- 
 ceed. Lastly, the presence in Argonauta of a testis with per- 
 fect semen, which probably passes thence into the Hectocotylus, 
 opposes altogether the hypothesis that the latter is a male gene- 
 ration proceeding from an asexual gemmiparous one. 
 
 For the other supposition, that the Hectocotylus, together with 
 its producer, forms only one animal, but after its separation 
 must be regarded as a continuation of the whole, because it is 
 the means of propagation of the species, analogous cases might 
 be adduced of certain animals in which the organs of individual 
 life retrograde in relation to those of the propagation of the 
 species. 
 
 It might be instanced that many Echinoderms, for example, 
 are produced by budding from larvae, which then waste away ; 
 and herewith might be compared the surprisingly great and 
 rapid development of the Hectocotylus-axm, as contrasted with 
 the small size of the other arms*. But before drawing such 
 comparisons, further observations must be obtained upon the 
 duration and mode of life of the two separated moieties of the 
 
 * In my specimens not more than six pairs of suckers are distinctly developed 
 upon three arms. 
 
ARGOXAUTA ARGO AND THE HECTOCOTYLI. 85 
 
 original animal. For we know as little how long the isolated 
 Hectocotylus, as how long the seven-armed Cephalopod, lives ; 
 whether the latter produces new Hectocotyli*, or passes through 
 yet other metamorphoses. In this respect it is remarkable that 
 male individuals of only a very small size relatively to the females 
 have been observed, and that, independently of sex, they exactly 
 resemble the very young females. The circumstance also that 
 many of the small animals had a tolerably advanced mass of 
 semen in the testis, and that others already carried perfect semen 
 in the seminal sac of the Hectocotylus-arm, rather indicates that 
 these males do not grow large, for the ova of females of the 
 same size are nowise developed to the same extent. If large 
 male Argonauts occur, they have been without doubt overlooked 
 in consequence of their wanting the expanded arms and the 
 shell. The specimens of the Octopus described by Verany are 
 indeed considerably larger ; and Cuvier says nothing about the 
 size of the animals which bore the Hectocotyli either in the 
 mantle or as an arm. Yet the case of an Octopus, brought for- 
 ward by Verany, which, in the usual place, had merely the pe- 
 dicle without an arm or vesicle, is the only direct evidence for 
 the continued existence of the Cephalopod which has cast off 
 the Hectocotylus. 
 
 Until more light is thrown upon these relations, it seems 
 unnatural to assume that all the most important organs of an 
 animal, the central organs of the circulating and nervous systems, 
 the apparatus of sense and digestion, and so forth, are thrown off 
 en bloc, and that the remainder with the semen, which is not 
 even produced in it, should continue to represent the individual. 
 
 4. If for the present then the Hectocotylus can hardly be 
 considered to be an entire individual, it only remains to regard 
 it as a separated portion of the whole. 
 
 Costa has expressed the view that the Hectocotylus Argonauts 
 is the spermatophore of the Argonaut (Annales des Sciences Na- 
 turelles, 1841, p. 184). The Hectocotylus might be rightly so 
 
 * In favour of a regeneration of the cast-off flectocotylus-arm we have the 
 fact, that not uncommonly this occurs with other arms. A small conical pro- 
 cess covered with a number of small suckers sprouts forth from the torn place 
 of the arm. 
 
86 MULLER ON THE MALE OF 
 
 called, if the word is to be taken in its general sense ; but it can 
 certainly not be classed together with the well-known seminal 
 cases of other Cephalopods which at present bear that name. 
 These spermatophora are mere capsules composed of a no further 
 organized mass, whose movements take place from purely me- 
 chanical causes. They are seminal machines, which might as 
 well be called a secretion, if the semen is to be so denominated. 
 The Hectocotyli, on the other hand, are composed of different 
 organs and of almost all the elementary tissues which exist, in 
 the same condition as they are found elsewhere in the living 
 body. I will not neglect, however, to draw attention to the 
 analogy which exists in many respects between the spermato- 
 phora and the structure above referred to in Hectocotylm Trem- 
 octopodis,as theductus deferens. In both the seminal mass is fixed 
 to a spiral band contained in a sheath, and its uncoiling appears 
 to be connected in the one case as in the other with the extru- 
 sion of the semen. The substance of the spermatophora, as of 
 the ductus deferens, is a mass which exhibits transitions from a 
 less to a more considerable consistence, and also from a complete 
 absence of structure to a striation, which, however,is riot produced 
 by any peculiar elementary parts. The substance of which the 
 capsules and pedicles of the ova are formed is similar, and in the 
 oviduct of Tremoctopus we find masses, of which it is not easy to 
 say how much proceeds from the Hectocotylus and how much 
 from the female herself. Should this analogy, upon which I 
 will not enter further here, be confirmed, the Hectocotylus Trem- 
 octopodis might at most be called a spermatophore-bearer. 
 
 In any case, the Hectocotylus of the Argonaut (and probably 
 also the two others) stands in the relation to the rest of the 
 animal, of an arm, which is at the same time penis and ductus 
 deferens. When separated it may be compared with any other 
 partj which separated from a living individual, yet preserves for 
 a certain time a given amount of vital properties. How far, as 
 regards amount and duration, this may extend, cannot be deter- 
 mined a priori, and the Hectocotyli may perhaps surpass all 
 hitherto known instances. 
 
 Nothing can better illustrate the character of their movements, 
 than that Lauriliard, Delle Chiaje and Kolliker were led thereby 
 
ARGONAUTA ARGO AND THE HECTOCOTYLI. 8? 
 
 to hold them for decidedly independent animals, and every 
 future observer will be unable to avoid the same impression*. 
 
 The circulation of the blood of the Hectocotylus, although its 
 course is only imperfectly known, is very lively and rhythmical. 
 It should be observed, that in detached arms of Tremoctopus a 
 rhythmical movement of the veins from the periphery to the 
 centre continued for half an hour after separation from the 
 body, although the animal had been dead for an unknown time. 
 The protracted contractility of separated portions of the Cepha- 
 lopoda, for example of the skin with the chromatophora, is also 
 already known. Yet in the whole male Argonaut the Hectoco- 
 tylw-arm was the part in which the reflex movement ceased 
 latest, since it continued to make apparently voluntary move- 
 ments for many hours after these had ceased in the rest of the 
 animal. How long the movement, and indeed the existence of 
 the Hectocotyli endure after their natural separation is altogether 
 unknown f, but probably for a considerable time, if copulation 
 be not effected ; if indeed they do not exist afterwards. 
 
 The presence of the appendages described as gills in Hecto- 
 cotylus Tremoctopodis is very remarkable : since they do not 
 occur in other Cephalopod- arms and Hectocotyli, and since, like 
 the penis, they appear to become still larger in detached Hecto- 
 cotyli, it is to be concluded that the Hectocotylus in question is 
 originally intended to have a longer separate existence. But 
 the other Hectocotyli also are evidently by no means torn off 
 accidentally, but from the manner of their occurrence as well as 
 
 * Verany mentions in comparison the gill-processes of Eolidse, which, when 
 detached, continue to move for many hours. 
 
 f Since it is not easy to keep Cephalopoda with Hectocotyli in confinement 
 long enough, it will be desirable to pay particular attention in future to their 
 occurrence at particular seasons of the year. Verany obtained the Octopus 
 Carena at different seasons ; Kblliker obtained the Hectocotylus Tremoctopodis 
 in August and September pretty frequently ; that of the Argonaut again but 
 rarely. I found most Argonauts without Hectocotyli before the end of Sep- 
 tember, but at that time and in the beginning of October the majority of the 
 large specimens possessed them. In the end of July and the beginning of Au- 
 gust I obtained Tremoctopoda pretty frequently, and usually with Hectocotyli 
 on one occasion there were eight of the latter in one day. Subsequently the 
 Tremoctopoda occurred only singly, and no longer contained any Hectocotyli. 
 Hence the deficiencies in my account of the //. Tremoctopodis, since I erro- 
 neously expected always to obtain the same supply as at first. 
 
88 MULLER ON THE MALE OF 
 
 the structure of their place of attachment, they are intended to 
 be detached *. In all probability, finally, the thin appendage 
 of the Hectocotylus in Argonanta and Tremoctopus finds its 
 way into the female sexual aperture only after the separation, 
 for we find almost all Hectocotyli filled with semen, and the 
 penis of Hectocotylus Tremoctopodis often is in an apparently 
 virgin condition. This is easily possible, considering the lively 
 twisting movements which the appendage in both Hectocotyli 
 makes, even independently of the rest of the body, and in Hec- 
 tocotylus Tremoctopodis it is rendered still more easy by the cir- 
 cumstance that in the other portions of the penis the epithelium 
 forms a multitude of recurved hooks, the hinder edge of each 
 cell riding on its neighbour. It is to be considered, however, 
 whether preliminary acts of coition do not first determine the 
 separation of the Hectocotylus from the rest of the animal. 
 
 It is remarkable enough, anatomically, that certain Cephalopod 
 males should be distinguished from those of the immediately 
 allied species by the presence of the Hectocotylus-arm ; but the 
 facts adverted to render the relations of the detached Hectoco- 
 tylus so peculiar, that one is forced either to remain in doubt, or 
 to come to the conclusion that the line of demarcation between 
 independent animated beings, and such as are not so, is by no 
 means so distinct as the schools draw it. 
 
 It is, however, hardly the time at present to draw any theo- 
 retical conclusions, when so many matters of fact remain to be 
 inquired into with regard to the known species of Hectocotylus 
 (and there may be others), by which perhaps all that has been 
 done may be upset again ; for what has been stated here can 
 only indicate in what direction future investigations must be 
 undertaken. I thus sum up the chief results : 
 
 1. Perfect male Argonauts occur distinguished from the fe- 
 males, which only have hitherto been known, by the absence of 
 the expanded " vela " upon the two upper arms. 
 
 2. These male Argonauts carry the Hectocotylus Aryonautce 
 
 * It is important to know whether changes in the size and form of all Hec-> 
 tocotyli occur after their separation ; whether, for example, the coalescence of 
 the everted edges of the skin in Hectocotylus Argonauts happens before or 
 after separation from the rest of the animal. In my free specimens the pig- 
 mented capsule was in all cases fully formed. 
 
ARGONAUTA ARGO AND THE II ECTOCOTYLI. 89 
 
 (D. Ch.) in a pedunculated sac in the place of the third arm of 
 the left side. 
 
 3. The thick end of the Hectocotylus is fixed to the pedicle, 
 while the thin coiled-up part is free. 
 
 4. By the bursting of the sac and the eversion of its edges, 
 the pigmented capsule on the back of the Hectocotylus arises. 
 
 5. The testis lies in the abdomen of the whole animal, the 
 external aperture of the ductus deferens being near the point 
 of the Hectocotylus-arm, whose thin appendage has at the same 
 time the function of a penis. 
 
 6. In the axis of the Hectocotylus there lies a chain of 
 ganglia. 
 
 7. It is not to be supposed that the Hectocotyli are developed 
 as vermiform embryos in especial bunches of ova. 
 
 8. The Hectocotylus Octopodis of Cuvier, which Verany has 
 shown to be the arm of an Octopus, is mainly distinguished from 
 the Hectocotylus Argonauts by its size, by the presence of a 
 capsule at the free end, and by its development as the third arm 
 on the right side, of the Octopus. 
 
 9. The Hectocotylus Tremoctopodis of Kolliker is distinguished 
 by its gills, by a peculiar structure of the ductus deferens, and 
 by the want of a pigmented dorsal capsule ; but it possesses a 
 ganglionic chain in its axis, its penis is a more delicate prolon- 
 gation of this, like the appendage of the Hectocotylus Argonaulce, 
 and its cleft abdominal capsule is to be compared to the lobe 
 upon the appendage of the latter. 
 
 10. The Hectocotylus Tremoctopodis is thence to be considered 
 analogous to the two other Hectocotyli) although the animal as 
 whose arm it is developed is not at present known. 
 
 11. Each Cephalopod with a Hectocotylus-arm is to be re- 
 garded as the male of the corresponding female Cephalopod. 
 
 12. The Hectocotyli are intended to separate from the rest of 
 the body, and are then received and lodged by the female. 
 
 13. In this condition they have apparently independent mo- 
 tion and circulation ; they contain perfect semen ; and in Trem- 
 octopus, as also probably in Argonauta, a copulation with the 
 female animals takes place. 
 
 14. The Hectocotyli are not comparable to the spermatophora 
 
90 MULLER ON THE MALE OF 
 
 of other Cephalopoda; but perhaps the so-called ductus de- 
 ferens in Hectocotylus Tremoctopodis is similar to the?e. 
 
 15. The free Hectocotyli can by no means be regarded as 
 independent animals. 
 
 NOTE BY PROFESSOR KOLLIKER. 
 
 I desire to take this opportunity of stating, that I have con- 
 vinced myself of the truth of the most important of the discoveries 
 made by M. Miiller, by examining the Cephalopods which he 
 has brought, and that I entirely agree with his view of the re- 
 lation of the Hectocotylus Argonauta to the male Argonaut. As 
 it now appears, I was led formerly to put too great a value 
 upon the statements of Maravigno and Madame Power, and I 
 was thence induced to consider the Hectocotyli as male Cepha- 
 lopoda which were developed as such in the ovum. It appears 
 now that I was indeed right in the main, when I claimed the 
 Hectocotyli as belonging to the Cephalopoda ; but that they are 
 not complete animals, but only parts of them, separated indeed in 
 a very strange manner, and by the great independence of their 
 organization and vital manifestations forcibly resembling inde- 
 pendent animals. 
 
 KOLLIKER. 
 
 EXPLANATION OF FIGURES 1 AND 2 OF PLATE I. 
 
 (Both figures are magnified somewhat more than four times.) 
 
 * Represents the natural size. 
 
 Fig. 1. The perfect male Argonaut seen from the left side : the numbers in- 
 dicate the pairs of arms ; the second and fourth arms of the left side 
 are thrown back, in order to show in what manner the sac containing 
 the Hectocotylus is fixed by its pedicle in the place of the third arm. 
 Over the exterior of the sac a ridge extends longitudinally. 
 
 Fig. 2. A male Argonaut in the same position, only the Hectocotylus has come 
 out of its sac. The sucker-bearing portion is twisted once completely 
 round upon its own axis, so that it is seen at first from one side, then 
 from above, then from the other side, then in the ascending portion 
 directly from below, and again upon the same side as at first. The 
 fixed end of the Hectocotylus is still covered by the pigmented mem- 
 brane of the sac ; further on the latter is torn longitudinally upon the 
 
ARGONAUTA ARGO AND THE HECTOCOTYLI. 91 
 
 sucker-side towards the mouth, and so inverted in consequence of the 
 Hectocotylus being bent back, that one looks upon what was previ- 
 ously the inner surface of the sac: the chromatophora glimmer 
 through only indistinctly. The margins of the cleft lie in the con- 
 cavity of the first flexure ; one margin passes before, the other behind 
 the thick end of the Hectocotylus ; both unite at * on the dorsal side. 
 Between the edges and the white streak which indicate the seminal 
 sac there is a pit, whose inner surface is formed by what was pre- 
 viously the outer surface of the sac. Where the sucker-bearing part of 
 the Hectocotylus passes into the filiform appendage (penis), the lobe 
 appears on the back, and from this on each side a fold passes on to 
 the appendage. 
 
 [T H. H.] 
 
92 SIEBOLD ON HECTOCOTYLUS. 
 
 ARTICLE III. 
 
 A few Remarks upon Hectocotylus. By C. TH. VON SIEBOLD, 
 Professor at the University of Breslau. 
 
 [From Siebold and Kblliker's Zeitsclirift for June 1852.] 
 
 1 HAVE read with the greatest interest the recent discoveries 
 of Verany and H. Miiller as to the true nature of the Hectoco- 
 tylL I have now, with Kolliker, arrived at the persuasion 
 that Madame Power, through the too great positiveness with 
 which she described the development of the Argonauta in the 
 egg, has partly been the cause of the hitherto erroneous views 
 that have been entertained upon the subject. Since Maravigno, 
 in fact, only reported upon the communications concerning Argo- 
 nauta made by Madame Power to the Academy of Catania, it is 
 difficult to say for how much share in the error he is responsible 
 by additional careless observations of his own. From the first 
 I was desirous to have a sight of the figures which Madame 
 Power added to her treatise, and which neither Oken, Creplin, 
 Erichson^ nor Kolliker had as yet seen. I availed myself of my 
 last visit to Vienna to examine Madame Power's treatise in the 
 Atti dell' Accademia Gioenia di Scienze Naturali di Catania 
 (torn, xii.), contained in the Imperial Library, and especially to 
 convince myself of the resemblance of the figures of Argonauta 
 embryos given by Power, with Hectocotylus. I found that the 
 complaints made by Oken (Isis, 1845, p. 617) about the careless 
 editing of these academical papers were fully j ustifiable, since 
 even in this Viennese copy of the twelfth volume the illustrative 
 plate of Madame Power's essay w-as wanting. In accidentally 
 turning over the leaves of some of the succeeding volumes, how- 
 ever, I came in the fourteenth volume upon the missing plate. 
 Figs. 1-4 represent, somewhat magnified, but very coarsely 
 executed, a something which has a remote resemblance to a 
 Hectocotylus ; one distinguishes an elongated clavate body, one 
 end of which runs out into an acute point, and whose thicker 
 end is provided laterally with a double series of indistinct pro- 
 
S1EBOLD ON HECTOCOTYLUS. 93 
 
 minences. Figs. 1-3 exhibit five or six such elevations upon 
 each side. Fig. 4, on the other hand, has ten upon each side. 
 Fig. 4 then differs from the three preceding figures only by the 
 increased number of the lateral elevations, and yet Madame 
 Power says (see Wiegmann's Archiv, 1845, vol. i. p. 378, or 
 Oken's Isis 9 1845, p. 610) of this fourth form, which she sup- 
 poses to be an embryo three days old, that from this stage 
 elevations like buds gradually arise, provided with a double 
 series of dark points, and that these are the commencement of 
 the arms and their suckers ; where, however, in fig. 4 these com- 
 mencements of the arms are supposed to be, I can by no means 
 comprehend ; for this body, described and figured as an embryo 
 three days old, reminds one only of the arm of a Cephalopod 
 with its double row of suckers. Had Kolliker chanced to see 
 these figures, he would certainly have still more strongly be- 
 lieved that the Hectocotylus actually leaves the egg in its proper 
 form. 
 
 Now that Verany and H. Miiller have drawn attention to the ex- 
 ternal sexual differencesof the Cephalopoda, the different accounts 
 given by Aristotle of the sexual distinctions and functions of the 
 Octopus acquire an especial value, since Aristotle appears to have 
 been acquainted with the natural history and internal structure 
 of the Cephalopoda to an extent that we must even now con- 
 sider astonishing. From the following passages, which 1 here 
 extract verbatim from Schneider's translation (Aristotelis de 
 Animalibus Historic, book x.), Verany and H. Miiller, who have 
 produced a new phase in the history of Hectocotylus, will learn 
 with astonishment, that Aristotle may fairly contest with them 
 the priority of their discovery of the relation of the male Octopus 
 to the Hectocotylus-arm. In fact, in book iv. chap. 1, 6 (loc. 
 cit.) 9 it is thus written : " Polypus (such is Aristotle's inva- 
 riable designation for Octopus) brachia sua ad officium cum 
 manuum turn pedum accordat: namque duobus, qua? supra 
 os habet, admovet ori cibum. Postremo autem omnium, est 
 hoc inter cetera acutissimum et solum aliqua parte candidum in 
 dorso (vocatur autem dorsum pars brachii laevis a qua prorsum 
 acetabula collocata sunt) et in extremo bifidum hoc igitur ad 
 coitum utitur." 
 
 In the fifth book, chap. v. 1, we find further: "Aiunt non- 
 
94 SIEBOLD ON HECTOCOTYLUS. 
 
 nulli, marem habere non nihil simile genitali in uno ex brachiis, 
 quod duo maxima acetabula continet; id protendi quasi nervo- 
 sum usque in medium brachium atque totum in narem (funnel) 
 -fbeminae inseri." 
 
 In the same book, chap. x. 1, lastly, Aristotle returns once 
 more to the sexual distinctions of the Cephalopoda in these 
 words : " Differt a foemina mas capite (abdomen) oblongiore et 
 id quod genitale vocant piscatores habet in brachio candidum." 
 
 The task now remains for those observers who have the op- 
 portunity of investigating that portion of the Mediterranean 
 which lies between Greece and Asia, to decide what species of 
 Octopus Aristotle understood by his " Polypus," and how far 
 his acquaintance with the sexual relations of the male Octopus 
 coincides with the history of the Hectocotylus as it has been 
 recently made known. 
 
 [T. H. H.] 
 
II. VON MOHL ON CELLULOSE. 95 
 
 ARTICLE IV. 
 
 Investigation of the question: Does Cellulose form the basis of all 
 Vegetable Membranes? By HUGO VON MOHL. 
 
 [From the Botanische Zeitung, vol. v. p. 497 et seq."] 
 
 IN a former paper* I laid down the anatomical and chemical 
 reasons which led me to persist in maintaining the doctrine of 
 the growth of the membrane of the elementary organs of plants 
 propounded by myself and attacked by various writers, and 
 induced me to reject the view, defended by the Utrecht professors, 
 Mulder and Harting, that the outermost layers of those mem- 
 branes are the youngest and the inmost the oldest. Since that 
 paper was written I have carried through a long series of new 
 observations for the further elucidation of the conditions here in 
 question, the results of which, so far as relates to the chemical f 
 characters of vegetable membranes, 1 believe may be published 
 with advantage, because they may serve to throw light upon 
 some points as yet unknown, and to refute the chemical evidence 
 brought forward by Harting and Mulder in favour of their view. 
 In the Essay already referred to, I closely discussed the 
 opposition presented by the deductions drawn by Mulder and 
 Harting on one side, and by myself on the other, from the known 
 reaction of cell-membranes when acted on by sulphuric acid and 
 iodine. My opponents are of opinion that the circumstance of 
 thin recently formed membrane being coloured blue by iodine 
 and sulphuric acid, while in many full-grown cells only the inner 
 layer manifests this reaction, while the outer are tinged yellow 
 by these two substances, gives ground for the deduction that 
 these outer layers have been formed subsequently to the others, 
 and that the inmost layers of the full-grown cells are the same 
 membranes which constituted alone the wall of the young cell. 
 On the other hand, I asserted that this conclusion is too hasty, 
 
 * Bofanische Zeitung, vol. iv. p. 337 et scq. Translated in the Annals of 
 Natural History, vol. xviii. p. 145 et seq. 
 
 t I shall speak of the anatomical conditions on another occasion. 
 
96 H. VON MOHL ON CELLULOSE. 
 
 since a particular layer of an elementary organ may undergo a 
 chemical metamorphosis in the course of time, without experi- 
 encing on that account any alteration in dimensions, or affording 
 cause for it to be regarded as a new layer in an anatomical sense 
 of the word : I stated that in respect to this metamorphosis we 
 have to consider two possibilities, since it might arise either 
 through the cellulose of which the layer was originally composed 
 becoming dissolved and replaced by some other chemical com- 
 pound, or through the persistent cellulose becoming saturated 
 by another compound, and hence losing the capability of reacting 
 with iodine and sulphuric acid. For various reasons I declared 
 the latter view r , which certainly offers the most glaring contra- 
 diction to the views of the chemists, to be the more probable, 
 but I could not distinctly prove it, because I was unable at that 
 time to extract the infiltrated matters from such membranes as 
 offered an obstinate resistance to the action of sulphuric acid and 
 iodine, and in which cellulose could not be demonstrated to 
 exist by the application of those reagents ; such a process of 
 extraction being necessary to render the cellulose (which I 
 assumed to form the basis of the membranes) accessible to the 
 action of the iodine. Now, as the following pages will show, I 
 have succeeded in this with all the elementary organs of vege- 
 tables, and I therefore assert most distinctly that the walls of all 
 the elementary organs of plants are composed of cellulose ; that 
 it is quite inadmissible to draw conclusions as to the period of 
 origin of any given layer of their walls from its chemical condi- 
 tions, and that in regard to this question anatomical evidence 
 alone is valid. 
 
 In order to establish this proposition, I am compelled to enter 
 somewhat minutely into the details of my investigation : if I 
 enter into more extended explanations of the methods I followed 
 than seems to many altogether necessary, this is to be attributed 
 to the circumstance that I only arrived at determinate conclusions 
 after many unsuccessful experiments, and I wish others to be 
 able to confirm the correctness of my views. 
 
 Cuticle stands first of all the structures, in which it is impos- 
 sible to demonstrate a trace of cellulose by iodine and sulphuric 
 acid. It either completely withstands the action of sulphuric 
 acid, or, if it undergoes a certain degree of softening by this acid, 
 
H. VOX MOHL ON CELLULOSE. 9? 
 
 this never causes iodine to produce a blue colour in the substance 
 of the membrane, but the latter is always coloured yellow or 
 brown by the application of those reagents. The results are very 
 different when cuticle is subjected for some time to the action of 
 caustic potash. For this purpose a thin section of some epidermis 
 possessing a thick cuticle, for example that of the leaf of Aloe 
 obliqua, must be kept from 24 to 48 hours in a strong solution 
 of caustic potash, between two slips of glass, at ordinary tempe- 
 ratures. The solution I used was so concentrated, that crystals 
 of hydrate of potash were formed when the temperature of the 
 room fell to freezing-point. It is not requisite that the potash 
 should be chemically pure. When the action of the potash on 
 the cuticle was strong enough, the microscope revealed that 
 numerous little drops exuded from it, of a tenacious fluid, not 
 mixing with the solution of potash, but becoming yellow with 
 iodine. The cuticle itself was somewhat swollen up and showed 
 itself (like the membrane of thick- walled cells treated with 
 sulphuric acid) to be composed of numerous superimposed 
 lamellae, which were not continued uninterruptedly from one cell 
 to another, and hence did not form a connected layer lying upon 
 the epidermis and distinguishable from it, but terminated at the 
 boundaries of contiguous epidermal cells and formed part of 
 their walls. In most cases the epidermal cells had expanded 
 somewhat in the direction of their breadth, and the vSegments of 
 the cuticle corresponding to the individual epidermal cells had 
 become more or less perfectly separated from each other. When 
 a few drops of a strong tincture of iodine* are applied to the 
 preparation, the latter dried, and then wetted with water, the 
 cuticle acquires as bright a blue colour as the walls of the epi- 
 dermal cells and the subjacent parenchyma. The purity of the 
 colour is increased, as in most cases in which a cellular membrane 
 is coloured blue by iodine without the application of sulphuric 
 acid, by allowing the preparation to dry up once or twice after 
 being saturated with iodine and wetted with water, and then 
 
 * In these, as in all the following researches, I used a tincture of iodine, in 
 preparing which I added an excess of iodine, so that part of this remained 
 undissolved at the bottom of the alcoholic tincture. The attempt to apply a 
 tincture made with sulphuric aether instead of the alcoholic, so as to gain time 
 by the rapid drying, was not accompanied by good results, since this tincture 
 did not wet the preparation so perfectly as that made with alcohol. 
 
 SCIEN. MEM. ,Vfl*. ///*/. VOL. I. PART II. 7 
 
98 H. VON MOHL ON CELLULOSE. 
 
 wetting it again with water, and if requisite also a second time 
 with tincture of iodine. 
 
 A similar result is obtained by cutting off a section of the 
 cuticle parallel to the surface of the leaf, and treating it in the 
 same manner with potash and iodine. The cross-sections of the 
 side-walls of the epidermal cells, composed of cuticular substance, 
 exhibit exactly the same appearance as the other thick-walled 
 cells, composed of a number of superimposed layers ; between 
 them runs an external membrane common (?) to the two adjacent 
 cells, which has frequently a yellow or greenish colour at the 
 first wetting with water, but becomes likewise blue after a 
 repetition of the operation. When the cells have separated from 
 each other, this outer membrane is torn irregularly and hangs in 
 fragments attached to one or other of the contiguous cells. 
 
 The cuticle of other fleshy or leathery leaves, for instance of 
 Aloe margaritifera, Hoy a carnosa y Hakeapachyphylla, Hake a gib- 
 bosa, &c., behaves exactly in the same way as that of Aloe obliqua. 
 
 These statements place it beyond doubt that the cuticle of the 
 leaves mentioned is not a homogeneous layer of substance dif- 
 ferent from cellulose, secreted upon the surface of the epidermis, 
 but that this membrane is composed of separate segments corre- 
 sponding to the epidermal cells ; that it is composed of numerous 
 superincumbent lamellae of cellulose ; and that its chemical 
 diversity from cellulose arises from the infiltration of a substance, 
 coloured yellow by iodine, which not only resists the action of 
 sulphuric acid itself, but protects the cellulose which is saturated 
 with it from the influence of sulphuric acid and iodine. The 
 result is the demolition, in regard to the thick cuticle of thick- 
 walled epidermal cells, of the evidence advanced on chemical 
 grounds against the view I formerly advanced (Vermischte 
 Schriften, p. 260) of the structure of cuticle, namely, that it is not 
 a coating over the epidermis composed of substance excreted 
 from the latter, but owes its origin to a metamorphosis of a 
 portion of the outer walls of the epidermal cells. 
 
 The infiltrated substance was not totally extracted by macera- 
 tion of the epidermal cells for 24-48 hours in solution of potash, 
 for the addition of sulphuric acid to the preparation saturated 
 with iodine immediately reproduced the brown colour which is 
 caused in cuticle by these reagents before it is treated with 
 
II. VOX MOIIL ON CELLULOSE. 99 
 
 potash, and the same phenomenon is seen in the wood-cells when 
 the solution of the infiltrated substance is imperfect. 
 
 While the above-described action of potash on the cuticular 
 layer of epidermal cells is taking place, a very thin pellicle 
 becomes detached from the outer surface of the epidermis, either 
 in strips, or, when the epidermal cells separate from each other, 
 a piece of this coat remains adherent upon the outer side of each 
 of them. This pellicle is not coloured blue by iodine, but always 
 yellow. When the above treatment is applied to the epidermis 
 of organs in which the outer wall of the epidermal cells is not 
 much thicker than their side walls, and in which iodine and sul- 
 phuric acid demonstrate only a very thin cuticle, for instance, 
 of the leaves of Iris fimbriata, of stems of Epiphyllum truncatum, 
 of the petiole of Musa, &c., a thin yellow pellicle remains here 
 also on the outside of epidermal cells coloured blue by iodine. 
 If the epidermis is boiled with solution of potash, this pellicle 
 shrinks together and by longer boiling is completely dissolved, 
 while the epidermal cells only swell up and acquire a beautiful 
 blue colour with iodine. This pellicle, which occurs under all 
 circumstances upon the epidermis, whether it be a portion of its 
 cells transformed into cuticle or not, consists, judging from its 
 different behaviour with potash, of a substance essentially dif- 
 ferent from the cell-membrane, and is doubtless the same mem- 
 brane which Ad. Brongniart separated from leaves by maceration, 
 and denominated cuticle. It has been confounded, by myself 
 and others, with that portion of the w r alls of the epidermal cells 
 which is coloured yellow by sulphuric acid and iodine, under the 
 name of cuticle, because the methods of investigation hitherto in 
 use afforded no means of separating these two different parts 
 distinctly from each other. But it is evident that this membrane 
 must be distinguished from the subjacent cells ; I therefore pro- 
 pose to restrict the name of cuticle to it alone, and to apply the 
 term cuticular layer to that part of the epidermal cells which 
 becomes coloured yellow by sulphuric acid and iodine. The 
 cuticle exists on all cells exposed to the air, without exception ; 
 if any one choose to ascribe it to a secretion of the epidermal 
 cells, I have no objection to offer to the notion ; but it would 
 be difficult to bring forward any proof of its correctness ; and 
 perhaps we ought to regard the circumstance that this cuticle 
 
 7*' 
 
100 H. VON MOHL OX CELLULOSE. 
 
 is marked with raised lines in many plants, as a proof that it is 
 not to be considered simply as a hardened excreted fluid, since 
 possibly those lines ought to be looked upon as a proof of definite 
 organization. 
 
 The researches of Mulder and Harting have made known that 
 sulphuric acid and iodine do not demonstrate the existence of 
 cellulose in cork any more than in cuticle ; any one may readily 
 convince himself of the correctness of this statement in the cork 
 of the cork oak, of the elder, c. The cells also of the nascent 
 suberous layer, in their earliest condition, while still covered by 
 the epidermis, exhibit the same yellowish brown colour on the 
 application of the said reagents, as developed cork, even in those 
 plants in which the cork never attains any considerable develop- 
 ment, for instance in Cereus peruvianus. The conclusion drawn 
 from the absence of a blue colour, that the membrane of cork- 
 cells contains no cellulose, and is composed of a peculiar substance, 
 is, on the other hand, just as groundless as in the preceding case ; 
 for a thin section of the cork of the cork oak, which has been 
 boiled in solution of potash until the brown colour it originally 
 assumes has disappeared, acquires as bright a blue with iodine 
 as any other membrane composed of cellulose; in like manner, 
 and also by the application of nitric acid in the way described 
 below, the corks of Sambucus nigra, Acer campestre, Ulmus 
 campestris, and Euonymus europ&us, show that their cells are 
 composed of cellulose. 
 
 It is well known that the layer to which I have applied the 
 name of periderm, is, in anatomical respects, to be regarded as 
 a modification of the cork-layer. This circumstance led me to 
 conjecture that this membrane would display chemical characters 
 similar to those of cork. This was confirmed. I subjected the 
 periderms of the oak, of Crat&gus Oxyacantha, Betula alba, and 
 Plosslea floribunda, to the action of a boiling solution of potash, 
 after which iodine produced the blue colour. The blue colour 
 was quite clear in the oak and Cratcegus, but in the other two 
 less pure; the periderm of Plosslea, indeed, did not require a very 
 long boiling in solution of potash to produce the blue colour, 
 but only isolated patches of the cells were coloured pure blue, 
 the greater part acquiring a dirty blue tint. The periderm of 
 the birch, which very obstinately resisted the action of the potash, 
 
H. VON MOHL ON CELLULOSE. 101 
 
 required a long continuance of the boiling before the iodine would 
 produce the blue colour. 
 
 The organs above mentioned, forming the surface of plants, 
 especially the cuticular layer of the epidermis and the cork of 
 the cork oak, and in a less degree the corks of the other plants 
 enumerated, stand, in respect to the chemical properties of the 
 substances combined with their cell-membranes, preventing the 
 reaction of cellulose, in opposition to all those elementary organs 
 which form the internal tissues of plants. In these also the re- 
 action of cellulose is very frequently partially or entirely pre- 
 vented by compounds combined with them, but caustic potash is 
 not the proper means of reducing the cellulose of these organs 
 into a condition capable of the reaction. Even when, as in many 
 cases, for example in the secondary layers of many wood-cells, 
 such as those of the wood of Buxus, potash has this effect, the 
 result is often waited for in vain, and in case of success, the mem- 
 branes boiled with caustic potash but seldom acquire a pure blue 
 colour with iodine, and a yellow or brown colour is mostly min- 
 gled with it. On the other hand, the application of nitric acid 
 is always attended with complete success. 
 
 The effect of this acid is perhaps most perfect when the plant 
 to be investigated is allowed to macerate for a long time in 
 dilute acid, at ordinary temperatures ; but since in solid woods, 
 when even small fragments are placed in the acid, several months 
 or even a year may easily elapse before the effect of the acid has 
 completely developed itself, this method is scarcely applicable 
 when a large series of observations is to be made with this agent. 
 I therefore substitute a boiling of the substance to be examined 
 in moderately strong acid, for the long-continued maceration ; 
 by this means the desired effect is very rapidly obtained, only in 
 many plants the risk is run of dissolving the cell-membrane, or 
 at least some of its layers, by continuing the boiling too long. 
 This inconvenience, however, may be avoided by a little care ; 
 for in general the colour of the vegetable structure affords a mark 
 by which we can detect whether the required effect of the acid 
 has commenced and the boiling is to be stopped, or it is to be 
 continued for a longer time. At first, the acid ordinarily pro- 
 duces in the fragment of vegetable substances placed in it, 
 immediately it is heated, a yellow or brown colour, accompanied 
 by considerable effervescence and frequently with the formation 
 
102 H. VON MOHL ON CELLULOSE. 
 
 of vapours of nitrous acid, which colour however soon gives 
 place to a pale yellow, or a complete bleaching of the preparation. 
 When this bleaching takes place, the desired effect is generally 
 attained. I then brought the preparation, if it had not already 
 been boiled between two slips of glass*, on to a glass slider, 
 washed it with water, either dried it perfectly by a moderate 
 heat, or saturated the acid with ammonia, wetted the dried pre- 
 paration with strong tincture of iodine, let it dry up in the air, 
 and wetted it once more with water for microscopic examination 
 and to produce the blue colour. Sometimes it was necessary to 
 repeat the wetting with tincture of iodine, or to moisten the pre- 
 paration, saturated with iodine, with water, and let it dry again 
 several times. The whole process is somewhat tedious, but time 
 is saved, by setting to work with a number of preparations at 
 once, and, when they are saturated with tincture of iodine, letting 
 them dry at leisure, by which means we obtain sufficient material 
 for the whole day's work at the microscopic investigation. I 
 have frequently, to save time, assisted the drying of the prepara- 
 tion saturated with iodine by artificial heat ; as a rule, however, 
 it is more advantageous to allow the evaporation of the iodine to 
 go on at the ordinary temperature of the room, since even a 
 slight heating may easily cause too strong an evaporation of 
 the iodine. 
 
 It is well known that the parenchymatous cells of succulent 
 and young organs, in which the membranes are imbued with a 
 comparatively small quantity of the compounds coloured yellow 
 by iodine, require no preparation to render them capable of as- 
 suming a blue colour with iodine (see my Vermischte Schriften, 
 p. 344). It is different with the parenchymatous cells of older 
 structures which have become saturated with encrusting sub- 
 stances, for instance, the cells of pith and of medullary rays, &c. 
 Very frequently these cannot be coloured blue at all, or only 
 very imperfectly with iodine alone, and do not assume a pure 
 blue tint even with iodine and sulphuric acid, but are tinged with 
 
 * In all cases when it is desired to boil a thin cross section of a vegetable 
 structure in nitric acid, it is advisable to place it in a few drops of acid upon a 
 slip of glass, to lay a thickish covering-glass over it, and then place the glass 
 slip (to avoid cracking it) upon a metal plate which can be heated until the acid 
 boils. The most delicate preparations may be boiled in this manner, while they 
 almost inevitably tear up into fragments when it is attempted to boil them in a 
 glass tube or a platinum spoon. 
 
H. VOX MOHL ON CELLULOSE. 103 
 
 a dirty blue, so that it remains doubtful whether cellulose forms 
 any considerable part of their substance, or even whether it is 
 present at all, at least in some of the layers. These circum- 
 stances very readily explain why Mulder, who thought he had 
 an unerring and very delicate test for cellulose in the application 
 of sulphuric acid and iodine, was of opinion that the pith of 
 Sambucus nigra, for example, was composed of cellulose only in 
 the earlier conditions, and of a peculiar substance in the full- 
 grown state. But the matter turns out quite differently when 
 this pith is treated in the manner above described with boiling 
 nitric acid, for it then assumes a beautiful indigo-blue colour 
 with iodine. 
 
 While iodine and sulphuric acid produce, if not a bright blue, 
 at least a green colour in old parenchyma-cells, and thus the 
 presence of cellulose is placed beyond doubt even by this method 
 of investigation, the brown cells which surround the vascular 
 bundles of Ferns usually resist sulphuric acid as obstinately as 
 even cuticle, and it is absolutely impossible to demonstrate the 
 presence of cellulose by its help. In the essay above referred 
 to, I endeavoured to show on anatomical grounds, that this mem- 
 brane in the Ferns is produced by the transformation of a cellu- 
 lose membrane, but was compelled to leave undecided whether 
 or not it still contained cellulose in its fully developed condition. 
 The application of nitric acid affords an easy means of deciding 
 this question, and furnishes the proof that this membrane is 
 only prevented from reacting with iodine by its combination 
 with some infiltrated substance. For instance, if the black 
 membrane surrounding the vascular bundles of the petiole of 
 Aspidium filix mas, is boiled in nitric acid until its dark brown 
 colour is changed into bright yellow, iodine imparts a beautiful 
 blue colour to the membrane of these cells, the texture of which 
 is not changed in the slightest degree. 
 
 In many cases, in the Ferns, other portions of their cellular 
 tissue are so saturated with foreign compounds that they do not 
 react with iodine and sulphuric acid. Among these, for example, 
 are the outer layers of the dark brown petiole of Adiantum 
 pedatum, on the cells of which the said reagents do not act at 
 all at first ; only when the acid has been in contact with the cells 
 for twenty-four hours does the blue colour which shows itself at 
 
104 H. VON MOHL ON CELLULOSE. 
 
 the circumference of the preparation lead to the recognition of 
 the presence of cellulose in those cells, while the membranes 
 themselves remain yellowish brown. Here again a short boiling 
 in nitric acid suffices to render the membranes capable of taking 
 a very beautiful bltie colour. 
 
 In particular parts of the cellular tissue of Polypodmm 
 percussum, the outer coat of the parenchymatous cells acquires 
 a yellow colour with iodine and sulphuric acid, while the inner 
 layers swell up and become blue; in a word, they behave in this 
 respect like the outer coat of wood-cells. In preparations boiled 
 with nitric acid the cells are coloured blue throughout ; therefore 
 in these also cellulose is the basis of the outer layer, resisting 
 sulphuric acid. 
 
 Such cells, resisting the action of sulphuric acid, are more 
 common than would be supposed from what has generally been 
 stated; for many thick-walled parenchyma-cells, in the same way 
 as many wood-cells, assume only a yellow or at most a greenish 
 tint with the said reagents, as is the case in the parenchyma- 
 cells of many Palm-stems, e.g. of Calamus, of Cocos botryophora, 
 in the thick-walled pitted cells of the pith and rind of Hoya 
 carnosa, in the stony cells of the winter pear, &c. All these 
 cells assume a bright blue colour with iodine after they have 
 been boiled with nitric acid ; the statement of Mulder, that the 
 thick-walled pith-cells of Hoya contain no cellulose, is conse- 
 quently without foundation. 
 
 Since nitric acid is capable of rendering the cellulose ac- 
 cessible to the reaction of iodine in cells which more or less 
 obstinately withstand sulphuric acid, it may readily be imagined 
 that this acid never fails us in common parenchyma-cells, in 
 which sulphuric acid and iodine readily produce a blue, when 
 we desire to impart the blue colour to such cells by means of 
 iodine. This always presents itself in the greatest purity, and 
 without requiring the continuance of the boiling long enough to 
 alter the texture of the cell-membrane in the slightest degree. 
 When it is desired to facilitate the anatomical investigation of 
 cells by the production of this blue colour, for instance to exa- 
 mine minutely their pits, which always appear far more distinct 
 in the blue- coloured cells, this method is far preferable to the 
 application of sulphuric acid, from the very fact that it does not 
 
H. VON MOHL ON CELLULOSE. 105 
 
 cause any change in the texture of the cells. The blue colour 
 shows itself uniformly, whether we investigate thin-walled, still 
 succulent cells, such as the rind-cells of woody plants or herba- 
 ceous vegetables, the cells of the parenchyma of the leaf and 
 petiole, or the dead cells of the pith or medullary rays of old 
 wood. The walls of epidermal cells saturated with cuticular 
 substance, and the cork and periderm of many plants, only, are 
 inaccessible to the action of nitric acid ; in this latter respect, 
 however, the cells of the periderm and cork of other plants form 
 an exception, since cellulose can be demonstrated in them not 
 only by potash but also by nitric acid, for instance in the peri- 
 derm of Plosslea, the cork of Sambucus nigra, Acer campestre, 
 Euonymus europaus, and Ulmus campestris. Yet in these cases 
 it is generally necessary to boil the preparation for a long time 
 in the acid, and the effect is mostly imperfect, as these parts do 
 not usually become coloured blue completely after this treat- 
 ment; there exist, however, some structures belonging to the 
 cork system in which nitric acid is capable of producing a perfect 
 blue colour, while only a greenish tint is obtained by the appli- 
 cation of caustic potash, for example the spines belonging to 
 the suberous system of Bombax and the corky rind of the rhizome 
 of Tamus Elephantipes. 
 
 The cell-membranes which assume a blue colour after the 
 boiling with nitric acid usually form a very permanent combina- 
 tion with iodine. While in other cases the iodine which has com- 
 bined with a thin section of vegetable structure usually evapo- 
 rates entirely or in great part if the preparation is exposed for a 
 couple of days to the air, and may be extracted in a few seconds 
 with alcohol, preparations boiled with nitric acid and saturated 
 with iodine may often be left lying for weeks in the air without 
 the colour becoming perceptibly paler. In particular cases the 
 iodine combined with the membrane obstinately resisted not 
 only exposure to considerable heat, but the action of almost 
 absolute alcohol heated to the boiling-point. By alkalies, on the 
 contrary, especially by caustic ammonia, the iodine may be very 
 quickly extracted from the membrane. Only the cells of a few 
 of the plants which I investigated, in particular those of the 
 petiole of Cycas revoluta, formed exceptions to this rule, that the 
 iodine combined very firmly with the membrane. 
 
106 II. VON MOHL ON CELLULOSE. 
 
 In all the cases which I examined, the parenchyma-cells as- 
 sumed a pure blue colour through the entire thickness of their 
 membrane, and no yellow-coloured outer coat could be detected 
 at the boundary between the cross- sections of the walls of two 
 contiguous cells. In like manner the membrane which closed the 
 pits always exhibited a pure blue, or, in cells which were dried 
 and then assumed a violet colour, a bright violet, and here also no 
 trace of a yellow membrane lying between the cells could be seen, 
 as may be very distinctly observed in the cells of the petiole of 
 Cycas revoluta, especially on account of the large size of the pits. 
 When such cells, coloured blue by iodine, for instance those of 
 the pith of the elder, of the medullary rays of Buxus, the paren- 
 chyma-cells of the stem of Calamus, the cells of the petiole of 
 Cycas, &c., are placed in dilute sulphuric acid, their membranes 
 swell up strongly and finally dissolve entirely, becoming more or 
 less completely bleached in the process. Under this treatment 
 an extremely delicate yellow pellicle comes to light at the boun- 
 laries between the cells, to which pellicles small yellow-coloured 
 granules (or drops of a fluid substance ?) are in most cases ad- 
 herent. We are here reminded of an analogous structure de- 
 scribed by Mulder and Harting under the name of the "outer 
 cell-membrane," and the "cuticle of the wood-cells." The 
 question then arises whether this pellicle possessed the yellow 
 colour at the time the cells were coloured blue with iodine, or 
 was at first coloured blue like the inner layers of the cell-walls, 
 the yellow colour having been only produced subsequently by 
 the combined action of sulphuric acid and iodine. I regard it 
 as more probable that the latter was the case; for if that pellicle 
 possessed a yellow colour before the operation of the sulphuric 
 acid, we should have an indication of its presence in the trans- 
 verse slice of the walls of two contiguous cells, in spite of its 
 very slight thickness, and its yellow colour would cause a greenish 
 discoloration of the thin bright blue membrane which closes the 
 pits. Yet all my efforts to discover even a trace of such a yellow 
 membrane, with the application of the strongest objectives, which 
 gave a perfectly faultless image with a great amount of light, 
 were without the least success. Both this circumstance, and 
 above all the observations on the outer membrane of many 
 parenchyma-cells, to be mentioned below, lead me to conclude 
 
II. VON MOHL ON CELLULOSE. 107 
 
 that this outermost membrane of the parenchyma-cells also is 
 composed of cellulose and is coloured blue with iodine, but that 
 nitric acid is incapable of extracting the infiltrated matters com- 
 pletely, whence results the insolubility of this membrane in 
 sulphuric acid, and the yellow colour which it acquires from this 
 acid. In this respect this membrane would bear a resemblance 
 to the cuticular layer of the epidermal cells, in which caustic 
 potash, like 'nitric acid here, is capable of freeing the cellulose 
 from the influence of the infiltrated matters so far that it reacts 
 with iodine, but at the same time does not extract these matters 
 perfectly, and render the membrane saturated with them soluble 
 in sulphuric acid. 
 
 Among all the parenchyma-cells which I have investigated, 
 those which form the outer part of the pith of a shoot, several 
 years old, of Clematis Vitalba, are perhaps the most interesting 
 in regard to the structure of their walls. These cells have very 
 thick walls, and their membrane is composed of a tolerable 
 number of layers which may be easily distinguished. It is co- 
 loured yellow by iodine. Sulphuric acid causes the inner layers 
 to swell up, and at the same time they acquire a green colour : 
 under this operation an outer layer which is on an average y^r tn 
 of a line in thickness, remains wholly unchanged. This layer 
 therefore displays the character of Mulder's " outer cell-mem- 
 brane." When strong objectives are employed, a delicate line is 
 seen running through the middle of this layer, indicating the 
 boundaries of the contiguous cells. In a cross- section of these 
 cells boiled with nitric acid, the inner layers are coloured deep 
 blue by iodine, and the outer layer just described assumes, ac- 
 cording to the amount of action exerted by the acid, a yellow, 
 green, or blue colour. When such a preparation is wetted with 
 dilute sulphuric acid, the inner layers swell up strongly, they are 
 bleached and by degrees dissolved ; the outer layer also swells 
 to some extent, but very slightly, and is bleached, remaining other- 
 wise unaltered. If the preparation is placed in stronger acid, 
 this outer layer is also dissolved, leaving behind an immeasurably 
 thin pellicle (with adherent granules) which lie in the middle of 
 it. It is therefore evident that the outer membrane of these 
 cells, which at the first hasty glance might be taken for the 
 outermost coat, is also composed of cellulose, but that it is in- 
 
108 H. VON MOHL ON CELLULOSE. 
 
 filtrated either with a greater quantity of that substance, ac- 
 quiring a yellow colour with iodine, with which the inner layers 
 are saturated, or with some compound different from this, 
 opposing a greater resistance to sulphuric acid, which is so far 
 extracted or altered by nitric acid, that the reaction with iodine 
 occurs in the cellulose contained in this layer, but enough re- 
 mains to protect this layer from the action of weak sulphuric 
 acid, while in the outermost, immeasurably thin layer, the resist- 
 ance to sulphuric acid is so great that the latter is incapable of 
 dissolving it. 
 
 In reference to the question whether the above-described outer 
 brown pellicle of the parenchyma- cells contained cellulose, the 
 behaviour of the primary membrane of the cells of the horny 
 albumen of Sagus tcedigera seemed to me of considerable im- 
 portance, since here I could convince myself not only of the 
 absence of a yellow colouring of this pellicle, as in the other 
 parenchyma-cells, but positively of its acquiring a blue colour. 
 When the membrane of these cells is treated with a very weak 
 tincture of iodine, it is coloured bright yellow, and the primary 
 membrane deep yellow ; in such a preparation very dilute sul- 
 phuric acid produces a very bright blue in the secondary layers 
 of the cells, and a darker blue in their primary membrane, and 
 under these circumstances, the comparatively great transparency 
 of the cellulose allows one to become quite certain of the purity 
 of this colour and of the total absence of that yellow colour in 
 the outer primary coat. If stronger sulphuric acid is added, the 
 secondary membranes are bleached and gradually dissolved, 
 while the primary membrane turns yellow and becomes coated with 
 fine granules*. Under these circumstances it cannot be doubted 
 that the primary membrane is imbued with a greater quantity 
 of the substance coloured yellow by iodine, but that this is in- 
 sufficient to prevent the appearance of the blue colour under the 
 action of iodine and weak sulphuric acid; yet its presence may 
 be the. cause why a stronger acid does not dissolve this mem- 
 brane, for it is always found that a membrane resists the action 
 of sulphuric acid more strongly in proportion as it is more deeply 
 coloured by it and iodine. 
 
 * The granules, or minute drops (for there is no means of deciding whether 
 they are solid or fluid), are not separated until the sulphuric acid hcgins to act. 
 
H. VOX MOHL ON "CELLULOSE. 109 
 
 In reference to the characters of thin membranes, the liber- 
 cells generally approach to the parenchyma-cells, since ordina- 
 rily they do not possess either the great solidity and brittleness, 
 or the dark colour which distinguishes most wood-cells. This 
 greater resemblance between the liber-cells and parenchyma- 
 cells presents itself also in their behaviour to sulphuric acid and 
 iodine, since the former mostly assume a pure blue colour with 
 these reagents. On the other hand, the liber-cells of the arbo- 
 rescent Monocotyledons, especially of the Palms possessing 
 hard vascular bundles, are allied to the wood-cells of the Dico- 
 tyledons ; they are devoid not only of the softness and flexibility 
 which distinguish the liber-cells of many Dicotyledons, but in 
 many cases they exhibit also a yellow colour, sometimes passing 
 into the deepest brown. I examined the liber-cells of three 
 species of Palm, Cocos botryophora, Calamus, and the black- 
 fibred Brazilian palms, the wood of which is used for making 
 walking-sticks. When a cross-section of the liber-bundle of one 
 of these is treated with iodine and sulphuric acid, the secondary 
 layers are dissolved and the outer layer of the cells remains be- 
 hind undissolved, with a brown colour. This outer layer, which, 
 like the above-described outer layer of the pith-cells of Clematis, 
 corresponds, according to the characters given by Mulder, to 
 the " outer wood-membrane " of the wood-cells of the Dicoty- 
 ledons, and would be supposed to consist of a substance different 
 from cellulose, exhibits considerable thickness in a cross section, 
 and in Cocos botryophora (where it is about xuVo^ f a ^ ne 
 thick) is distinctly pitted. For these two reasons we cannot 
 regard it as the primary membrane of the cells, since in all 
 cases its not inconsiderable thickness and the presence of pits, 
 which do not perforate the membrane completely, but penetrate 
 only to a certain distance on both sides, lead us to conclude that 
 this layer is composed of several superincumbent lamellae. When 
 a cross section of a vascular bundle of these plants boiled in 
 nitric acid is treated with iodine, exactly the same phaenomena 
 present themselves as I have described in the pith-cells of 
 Clematis, namely, all the layers of the liber- cells, especially the 
 outer one withstanding sulphuric acid, are coloured bright blue, 
 \vhich proves that this latter also is composed of cellulose. If 
 dilute sulphuric acid is then added to such a preparation, not 
 
110 H. VON MOIIL ON CELLULOSE. 
 
 only are the inner layers of the cells dissolved, but also the 
 outer, which before this treatment with nitric acid were inso- 
 luble in sulphuric acid, and on the boundary-lines between the 
 adjacent cells, as in the parenchyma-cells, remains a pellicle of 
 the utmost delicacy coated with fine granules. Since in these 
 cells also, when very thin sections are coloured only pale blue by 
 a small quantity of iodine, it is impossible to detect by a yellow 
 colour this pellicle insoluble in sulphuric acid, I consider it pro- 
 bable that this possesses a blue colour so long as it is not ex- 
 posed to the action of sulphuric acid. The 7 presence of this 
 outer thin membrane, and the fact that it is only yellow under 
 the simultaneous action of sulphuric acid and iodine, and blue 
 with iodine alone, may perhaps be still more clearly proved by 
 macerating a vascular bundle of the black palm-wood in dilute 
 nitric acid (which however may require six to twelve months), 
 or boiling it in this acid until the liber-cells are separable by a 
 slight pressure. In this case isolated pieces of variable size of 
 the outer membrane may often be found among the separate 
 liber-cells, and we can then convince ourselves that they are 
 coloured blue by iodine, and only assume a yellow colour when 
 sulphuric acid is added. These are the observations which 
 principally led me to the opinion that the outer membrane of 
 parenchyma- and prosenchyma-cells contains cellulose, since the 
 impossibility of seeing the yellow colour in this membrane in 
 the cross section appeared not perfectly conclusive, on account 
 of its very slight thickness, though at the same time it must be 
 admitted that this circumstance is also of great importance. 
 
 Passing to the prosenchymatous cells of the wood of Dicoty- 
 ledonous plants, it is well known that cellulose may be demon- 
 strated in their internal layer by means of sulphuric acid and 
 iodine, but that these layers do not usually, it is true, assume a 
 pure blue colour with these reagents, mostly acquiring only a 
 green tint, which leads to the conclusion that cellulose does 
 really exist in them, but that its reaction is more or less obscured 
 by the presence of a yellow infiltrated substance. Even when, 
 as in the wood of Taxus> the resistance to sulphuric acid is very 
 considerable, the presence of cellulose may be shown by applying 
 a very strong acid, which completely destroys the texture of the 
 cell-wall, and then, by adding tincture of iodine diluted with a 
 
H. VON MOIIL OX CELLULOSE. Ill 
 
 great deal of water, the dissolved cellulose (which according to 
 this experiment is dissolved as such, and not as dextrine) is pre- 
 cipitated with a beautiful blue colour. But although these means 
 suffice to demonstrate the presence of cellulose, the application 
 of sulphuric acid is not adapted for the settlement of the question, 
 whether in such solid woods the cellulose forms always the 
 principal mass of the membranes and is only saturated with a 
 foreign substance, or the latter is predominant and the cellulose 
 only a very subordinate constituent. In this case the application 
 of nitric acid removes every doubt, inasmuch as the secondary 
 membranes of all wood-cells become bright blue through their 
 entire thickness with iodine, when they have previously been 
 macerated for a long time, or boiled until disorganized, in nitric 
 acid. The compound, therefore, which Mulder termed the " in- 
 termediate wood-substance/ 5 never itself forms the intermediate 
 layers of the wood- cells, but is a material infiltrated into them. 
 Since this result is quite universal, I regard it as superfluous to 
 mention particular examples, and confine myself to touching on 
 a few points which may be doubtful. 
 
 One of these refers to the character of the internal membrane 
 which lines the wood-cells in Taxus and Torreya, and of which 
 the spiral fibres running in these cells form part. This inner 
 coat, as was first shown by Prof. Hartig of Brunswick, resists 
 the action of sulphuric acid very strongly and under its influence 
 is coloured yellow by iodine, whence, relying upon these reagents, 
 as Hartig did, one might be inclined to assume that this membrane 
 was composed of a substance quite different from the interme- 
 diate layer, and contained no cellulose. The latter is by no means 
 the case, for the above-described treatment with nitric acid de- 
 monstrates, by the blue colour which this membrane and its fibres 
 assume, that these also are composed of cellulose. 
 
 The second point to be adverted to here, relates to the pits, 
 of which it might be doubtful, from the descriptions which 
 Hartig, Harting and Mulder have given of the structure of cells 
 and the characteristics of the " outer wood-membrane," whether 
 the membrane which closes the outer ends of the canals of the 
 pits is always composed of cellulose. In regard to this, there 
 can be no doubt in preparations of the Coniferre which have been 
 treated with nitric acid, since it is found that the pits are closed 
 
112 H. VON MOHL ON CELLULOSE. 
 
 by blue, although not brightly coloured, membrane, as I have 
 seen most distinctly in the wood of Taxus baccata and Abies 
 pectinata. But I must expressly remark, that observation of 
 this, as well as of the membrane which closes the pits of the par- 
 enchyma-cells, requires a microscope of the highest quality, fur- 
 nished with very strong objectives ; with objectives not of very 
 short focus, i. e. unless at least less than a line, even when the 
 image they give is perfectly free from error, the membrane closing 
 the pits will be sought in vain, since the penetrating power of 
 the microscope will be too small. 
 
 The most difficult point in the investigation of the wood-cells 
 is that of their outermost membrane (Mulder's " outer cell-coat/' 
 Harting^s "cuticle of the wood-cells"). 
 
 In the first place, the remark perhaps may not be superfluous 
 in reference to this membrane, that in many wood-cells we meet 
 with a case similar to that in the above-described pith-ceils of 
 'Clematis and the liber of Calamus and Cocos botryophora, 
 namely, that when a cross-section of the cell is soaked with 
 iodine, layers of two kinds may be distinguished, a thick inner 
 one, very brightly coloured, and a thinner outer one which 
 acquires a darker yellow colour with iodine and might readily be 
 taken for the primary membrane of the cell, e. g. in Buxus, in 
 particular cells of the wood of Erythrina caffra and of many 
 kinds of Ficus. This outer layer withstands the action of sulphuric 
 acid much more strongly than the inner, so that a weaker acid 
 suffices to cause a strong swelling up of the inner layer, bringing 
 out a blue or green colour, while the outer layer is quite unaf- 
 fected and remains yellowish brown. A stronger acid, however, 
 is capable of producing a green colour in the outer layer, or at 
 least of bleaching and dissolving it when the action is allowed to 
 continue for some time. Treatment of a cross section with boiling 
 nitric acid leaves no doubt of the true nature of the conditions, 
 since in a preparation so treated both layers are coloured bright 
 blue by iodine, and dilute sulphuric acid quickly dissolves even 
 the outer layer, so that any confusion of this with the outer cell- 
 membrane is out of the question. 
 
 The latter exhibits the same qualities as I have described 
 above of the outer coat of the parenchyma and liber; it is 
 extremely thin, withstands the action of sulphuric acid, and 
 
H. VON MOHL ON CELLULOSE. 113 
 
 is coloured yellow by this and iodine. It is just as difficult with 
 this outer coat of the wood-cells as with the outer layer of the 
 parenchyma-cells, to answer the question whether it is coloured 
 yellow or blue by iodine, but similar reasons render it probable 
 here also that the latter is the case. For if a transverse section 
 of a Dicotyledonous wood which has been boiled in nitric acid 
 is soaked with iodine, a yellow membrane may be detected 
 between the blue-coloured cells ; if the action of the acid has 
 been more powerful, this yellow colour is more and more lost 
 and passes through green into a perfectly pure bright blue, so 
 that no trace of any yellow membrane lying between the blue 
 cells can be seen here any more than in the parenchyma-cells. 
 This is the behaviour, for example, of the wood of Abies pectinata, 
 Larioe europaa, Taxus baccata, Torreya tazifolia, Buxus semper- 
 virenSy Viburnum Lantana, Viscum album, Betula alba, Fayus 
 sylvatica, Clematis Vitalba, Erythrina caffra. When dilute 
 sulphuric acid is added, the cell-membranes are dissolved with 
 a slow bleaching, arid there remains behind a network of immea- 
 surably thin yellowish- brown pellicles, which correspond to the 
 boundaries of the cells. 
 
 In most, perhaps in all woods, the intercellular passages 
 running between the wood-cells are filled up by an intercellular 
 substance, which is coloured yellow by iodine and sulphuric 
 acid, and not attacked by the latter, whence one might easily be 
 led to assume that this substance formed a common mass with 
 that membrane of the cells which likewise acquires a yellow 
 colour under these circumstances. But the incorrectness of 
 such a notion is proved by the examination of the preparations 
 boiled in nitric acid, since in these the intercellular substance 
 retains its yellow colour on the application of iodine, while the 
 outer cell- membrane is coloured blue. Whether the intercellular 
 substance of Dicotyledonous woods is wholly free from cellulose, 
 or contains it in a very strongly combined condition in which it 
 is not acted on by iodine, I cannot yet venture to decide. The 
 application of caustic potash to the investigation of this condi- 
 tion entirely failed me, and the application of nitric acid fur- 
 nished no decisive result. For if the boiling with nitric acid is 
 stopped before the texture of the cells is attacked, the intercel- 
 lular substance, as above mentioned, remains yellow on the 
 SCIEN. MEM. JVo/. Hist. VOL. I. PART II. 8 
 
114 H. VON MOHL ON CELLULOSE. 
 
 application of iodine ; while if the transverse section of a wood 
 is boiled longer than is requisite to impart to its cells the capa- 
 bility of acquiring a blue colour with iodine, under which cir- 
 cumstance the cells begin to separate from each other, the inter- 
 cellular substance is no longer found, being dissolved. I hoped 
 to find it in a transition state between these two extreme 
 cases, and then perhaps, if it contained cellulose, to be able 
 to detect this with iodine ; and, if I was not deceived, it indeed 
 happened with a few w r oods, for example, in Buxus sempervirens 
 and Clematis Vitalba, it assumed a bright blue colour after the 
 yellow had disappeared. This colour however was very pale, and 
 might possibly have depended on a bluish tinge thrown upon 
 the bleached intercellular substance by the surrounding dark 
 blue-coloured cells, so that I do not venture to declare the 
 observations certain, and must leave this point undecided for the 
 present. 
 
 To mention some of the examples in which an intercellular 
 substance with the said properties filled up the intercellular 
 passages between the wood-cells, I may name Larix europcea, 
 Taxus baccata, Torreya taxifolia, Viburnum Lantana, Buxus 
 sempervirens, Clematis Vitalba. 
 
 When the intercellular substance is dissolved by means of 
 nitric acid, the cells of the wood begin to part from each other. 
 It is difficult to trace accurately the process which occurs here, 
 since the blue colouring of the cell-membrane by iodine, which 
 would greatly facilitate the investigation, does not occur 
 unless the preparation saturated with iodine is allowed to dry 
 up ; but this drying causes a contraction and tearing of the 
 membranes, which places the greatest difficulty in the way of 
 detecting what goes on during the separation of the cells. The 
 notion might readily be formed that the separation of the cells 
 resulted from the solution of their outer membrane, as well as 
 the intercellular substance, by the nitric acid, and that the cement 
 which connected the cells together was thus removed. But if I 
 have rightly understood the operation, it is something quite dif- 
 ferent from this. The outer membrane is not dissolved, as is 
 easily seen when such preparations, saturated with iodine (whether 
 the cells have been separated from each other by boiling nitric 
 acid or by long maceration at ordinary temperatures), are treated 
 
H. VON MOHL ON CELLULOSE. 115 
 
 with sulphuric acid, under which circumstances the outer mem- 
 brane presents itself unchanged with a yellow colour, after the 
 rest of the cell-membranes have been dissolved. The separation 
 of the cells seemed rather to depend upon the outermost layer 
 of the secondary membranes becoming softened into a gelatinous 
 condition, and detached from the primary membrane. The cir- 
 cumstance that the outer layers of the cells are caused to swell 
 up and dissolve in strong acid sooner than the inner, is not un- 
 commonly met with, especially in treating with sulphuric acid 
 half gelatinous cells saturated with iodine, for example, the half 
 collenchymatous cells of the bark, like those of Erythrina cqffra. 
 In such cases it is very common for the outer layers of the swollen 
 cells to have a brighter blue colour than the inner, and when by 
 a longer action of the acid these inner layers also become per- 
 fectly blue, the outer layers are completely bleached. A similar 
 phaenomenon sometimes presents itself most distinctly under a 
 strongish action of nitric acid. This is especially the case with 
 the wood- cells of Clematis Vitalba, the outer layers of which, 
 when the boiling in acid is long continued, dissolve into an 
 amorphous jelly, which acquires a blue colour with iodine. Such 
 a perfect solution of the outer layers, however, is by no means 
 necessary to bring about the separation of the cells; even a slight 
 softening of the cell-membrane seems sufficient to separate the 
 secondary layers from the outer membrane, and thereby the 
 cells from each other. In favour of this, we have both the 
 microscopic examination of cross sections which have been boiled 
 in nitric acid till the cells have separated, and in which fragments 
 of delicate torn membranes, but no amorphous jelly, are met with 
 between the cells, and also the circumstance, that in the wood 
 of Abies pectinata, which had been macerated for about a year in 
 dilute nitric acid, and in which the elementary organs fell apart 
 on the slightest pressure, the canals of the pits were closed at 
 the outer ends by a thin membrane, which could not have been 
 the case if the outer membranes of the cells had been dissolved. 
 The extraordinary softness which the cell- membranes had ac- 
 quired, both in this wood and in the hard vascular bundles of 
 the black-fibred palm above-mentioned, when treated in the 
 same way, was remarkable. 
 
 In this separation of the cells, the outer coat never seemed to 
 
 8* 
 
116 H. VON MOHL ON CELLULOSE. 
 
 split into two lamellae remaining attached to the two adjacent 
 cells, but the membrane situated between two cells remained un- 
 divided, separating from both cells, or remaining attached to one 
 of them, which of course must have been accompanied by a dis- 
 ruption of it in other places, i When exactly the right period of 
 the action of the acid in which the wood is macerated, has been 
 hit, comparatively large pieces of the outer coat may be often 
 obtained isolated, by tearing up a piece of such wood with a 
 needle, since the cells may be readily extracted, as from a shell, 
 from the chambers formed by the cavities of the outer coat. 
 
 Proceeding to the Vessels, the different layers of the walls of 
 the forms containing spiral or annular fibres behave in the reverse 
 way to those of cells. In the latter, namely, when they are 
 greatly lignified, the outer layers are usually saturated most 
 strongly with foreign compounds, and therefore offer the greatest 
 resistance to the action of sulphuric acid, while the inner layers, 
 as the youngest membranes, are frequently coloured a beautiful 
 blue by iodine and sulphuric acid ; in the vessels, on the con- 
 trary, the secondary structures (the fibres) are those which most 
 strongly resist sulphuric acid, and only acquire a yellow 7 or at 
 most a green colour, while the tube on the inner wall of which 
 the fibres are deposited may acquire a bright blue with these 
 reagents. This difference is seen very beautifully in the vessel- 
 like elementary organs, furnished with flat, band-like spiral fibres, 
 of the wood of many Cactaceae, especially of the Mammillaritz. 
 When these elementary organs are treated with boiling nitric 
 acid, both the fibre and the outer coat are coloured bright blue. 
 In like manner the spiral fibres of the vessels of herbaceous 
 plants, for instance of Asparagus, may be coloured bright blue 
 after treatment with nitric acid ; in the vessels of many plants, 
 however, especially in the spiral vessels of Sambucus nigra and 
 the scalariform vessels of Tree Ferns, a rather long-continued 
 boiling in the acid is requisite to destroy the green colour and 
 bring out the pure blue. 
 
 The pitted vessels of the Dicotyledons approach the wood- 
 cells nearer than the spiral vessels in their behaviour with iodine, 
 since it is their outer layers which are principally infiltrated with 
 the foreign compounds coloured yellow by iodine. But treatment 
 with boiling nitric acid also produces the blue colour in all the 
 
II. VON MOIIL ON CELLULOSE. 11? 
 
 layers here, and not only in the thickened layers of the walls of 
 the vessels, but in the delicate membrane which closes the pits. 
 This was the behaviour, for example, in the vessels of Sambucus 
 nigra, Viburnum Lantana, Asclepias syriaca, Buxus sempervirens, 
 Clematis Vitalba, Betula alba, Quercus Robur, and Tilia. The 
 outermost membrane of these vessels behaves in every respect 
 like the outer cell-coat of the prosenchymatous cells of wood, and 
 similar reasons to those which testify that the latter contains 
 cellulose are furnished also by the outer membranes of vessels, so 
 that I may refrain from entering into minute details on this point. 
 
 The researches of Mulder and Harting have already made 
 known that the wall of the Milk-vessels contains cellulose ; and 
 in like manner I only think it necessary to state briefly that the 
 elementary organs of that part of the vascular bundles of Mono- 
 cotyledons which 1 have described under the name of proper 
 vessels (vasa propria) in the Palms, and elsewhere, acquire a 
 beautiful blue colour with iodine after treatment with nitric 
 acid. 
 
 Looking back over the researches here described, it appears 
 clear that the walls of all the elementary organs of vegetables 
 may be brought, by the action of caustic potash or of nitric acid, 
 into a condition in which they assume a blue colour with iodine, 
 and that the only exceptions to this among all the solid structures 
 of plants, are the cuticle, in the strictest sense of the term, and 
 perhaps the intercellular substance of the higher plants. 
 
 The action exerted by potash or by nitric acid upon vegetable 
 membranes is not merely transitory, enduring only while th j 
 action is kept up (as Mulder assumes of the action of sulphuric 
 acid upon cellulose), but is permanent, inasmuch as the mem- 
 branes which have been treated in the above- described way 
 retain the capability of taking a blue colour with iodine after the 
 active substance has been completely removed, as when the 
 nitric acid is neutralized by ammonia. The question now arises, 
 whether the cellulose itself suffers a transformation by the appli- 
 cation of these means, rendering it capable of taking a blue 
 colour with iodine, in the manner starch does, or, whether 
 these means act merely to extract or decompose more or less 
 perfectly the foreign compounds combined with cell-wall, whbh 
 acquire a yellow colour with iodine, and deprive cellulose of the 
 
118 H. VON MOHL ON CELLULOSE. 
 
 power of reacting with iodine. These questions must be answered 
 by chemists, and not by botanists. Yet I may be permitted to 
 allude to two points. A conversion of the cellulose into starch 
 is out of the question, for the cell-membranes treated in the way 
 described remained afterwards, as before, insoluble in boiling 
 water; if therefore a transformation of the cellulose is assumed, 
 it must be into some compound as yet unknown, the characters 
 of which have still to be minutely investigated. For the present 
 the assumption of such a transformation appears to me unwar- 
 ranted, in so far that the power of the cell-membranes to acquire 
 a blue colour with iodine is the only reason at present existing 
 which can be urged in favour of this, while I have already shown, 
 on previous occasions, that fresh, perfect, unaltered cell-walls of 
 many plants, particularly of young organs, also acquire a blue 
 colour with iodine, which indicates that cellulose possesses this 
 quality, as well as starch, in and by itself, whenever its reaction 
 is not prevented by other compounds united with it. For the 
 present, and until we obtain further explanations from the 
 chemists, it will be simplest to assume that the potash and nitric 
 acid bring about this reaction by removing such foreign com- 
 pounds from the encrusted membranes. 
 
 Looking from anatomical and physiological points of view, and 
 these alone I have occupied in my researches, I believe that I 
 have shown, from the latter, that the reaction of sulphuric acid 
 and iodine upon cellulose is altogether devoid of the trustwor- 
 thiness ascribed to it, and that the assumption based upon this 
 supposed trustworthiness, that particular layers are formed of 
 other compounds besides cellulose, in the course of the develop- 
 ment of the elementary organs of plants, and that the chemical 
 reaction of the different layers of a vegetable elementary organ 
 therefore affords a certain test of the relative epoch of its deve- 
 lopment, is totally devoid of foundation ; that, consequently, 
 all the objections against my theory of the development of the 
 walls of vegetable cells, built upon this basis, are completely un- 
 tenable, and that in this question anatomical evidence alone can 
 be admitted as proving anything. 
 
 [A. H.] 
 
VERANY AND VOOT ON THE HECTOCOTYLI. 119 
 
 ARTICLE V. 
 
 Memoir upon the Hectocotyli and the Males of certain Cephalo- 
 pods. By MM. J. B. VERANY and C. VOGT. 
 
 [Annales des Sciences Naturelles, t. xvii. No. 3, 1852.] 
 
 THE manner in which the fecundation of some Cephalopoda, 
 especially of the Argonaut and of the Tremoctopods, whose 
 females only have been known up to the present time, occurs, is a 
 zoological question of the highest interest. The very recent re- 
 searches of MM. Kolliker and Siebold having called the atten- 
 tion of naturalists to this point, we have neglected no opportunity 
 of procuring fresh and living animals, by the study of which we 
 hoped to arrive at, a definite solution of the problem. We ven- 
 ture to think that our investigations have been rewarded by 
 complete success, at least for one species. 
 
 The memoir which we now lay before the Academy relates 
 principally to the Tremoctopus Carena (Verany) and the Hecto- 
 cotylus which is derived from it. We shall give, first, a historical 
 summary of the labours of our predecessors ; then the zoological 
 description of the species which occupies us, and which was to 
 a great extent unknown up to the present time ; lastly, we shall 
 conclude our work by a detailed study of the reproductive 
 organs. 
 
 Historical Introduction. 
 
 M. Delle Chiaje, at Naples, described and figured in the year 
 1825* a little animal found by him parasitic upon an Argonaut, 
 to which he gave the name of Trichocephalus acetabularis. 
 This animal, when once detached from the Octopus, to which 
 it was adherent, swam and crept at the bottom of the water with 
 uneasy movements. It appeared full of life for many hours. 
 M. Delle Chiaje did not doubt that this parasite was one of the 
 Helminthic worms, and placed it in the genus Trichocephalus of 
 
 * Memorie sulla Storia e Notomia degli Animali senxa vertebre del regno 
 di Napoli ; di Stefano Delle Chiaje. 
 
120 VERAXY AND VOGT OX THE IIECTOCOTYLI 
 
 Rudolphi, although it was provided with a double series of 
 suckers, wishing, as he says, not to burden science with a new 
 genus. M. Delle Chiaje only describes the exterior of the ani- 
 mal. According to him it has a long, round, filiform, very con- 
 tractile proboscis, attenuated towards its extremity. The body 
 is provided with a double series of alternating and retractile 
 pedunculated suckers, by which the animal adheres to the skin 
 or to the shell of the Argonaut. 
 
 M. Laurillard discovered at Nice, upon the Octopus granulosus 
 of Lamarck, five specimens of a parasitic animal, which Cuvier 
 described subsequently as the Hectocotylus Octopodis*. Among 
 these five individuals three were found in the funnel of a female 
 Octopus, one was discovered in the same position in another 
 Octopus, and the fifth individual " had attached itself to an arm 
 of the Octopus, and had transformed it into a kind of sac, into 
 which it had introduced its head, the remainder of its body being 
 external and free." In recurring to this individual, Cuvier adds, 
 " The Hectocotylus has attached itself to one of the arms, which 
 it has even almost destroyed, and which it seems to replace in 
 such a manner, that at first sight it might be taken for the 
 arm itself." With our present knowledge, we must conclude 
 from these remarks that one of the Octopods taken by M. Lau- 
 rillard was a male, which had just disengaged its hectocotyli- 
 form arm from the sac in which it had been developed. 
 
 Cuvier describes the external form of the body, the suckers, 
 and the internal organization. None of his Hectocotyli had the 
 filiform organ, which we shall call the flabellum (lefouet), everted 
 from the sac which contains it. Cuvier found at the rounded 
 extremity of the body an alimentary orifice leading into a sac, 
 closed on all sides, and having a yellowish internal surface. This 
 cavity, which Cuvier calls a stomach, is nothing more than the 
 sac opening by a cleft, whose formation we shall subsequently 
 describe. Besides this stomachal sac, the clavate extremity 
 contains another " with stronger parietes, occupied by the innu- 
 merable folds of a thread which has the colour and brilliancy of 
 raw silk. One of the Hectocotyli ejected this thread very rapidly 
 at the moment of its capture." Cuvier is disposed to look upon 
 this thread as connected with generation. It is in fact the 
 * Annales des Sciences Naturelles, tome xviii. 1829. 
 
AND THE MALES OF CERTAIN CEPHALOPODS. 121 
 
 seminal thread contained in a spermatophore. Besides these 
 organs, Cuvier describes the muscular tube forming the axis of 
 the body, and continuous with a filament folded up in the ter- 
 minal sac, a filament which we have called the flabellum. 
 According to Cuvier, the point of this flabellum is bent back 
 into the body of the animal, and is directly continuous with the 
 seminal thread. We know not to what circumstance we must 
 attribute this mistake, for in all the specimens we have exa- 
 mined, the flabellum has been found completely free at its ex- 
 tremity. 
 
 The note which was published at a later period by M. Costa 
 of Naples, upon the Hectocotylus Argonautae*, only added to 
 the controversy the opinion of the author, who looks upon this 
 animal as the spermatophore of the Octopus. M. Costa's de- 
 scription is besides altogether incorrect, and the figure is as bad 
 as it can be. The sac of the flabellum is represented like a 
 pennant ; the extremity of the true spermatophore as a tenta- 
 cular cirrhus with two points ; the convolutions of the seminal 
 thread appeared to M. Costa to be spots formed by little spiral 
 vessels. 
 
 M. Dujardin, in arranging the Hectocotyli among the doubtful 
 Trematoda, thus gives his opinion upon these parasites f * " I 
 have seen the anatomical preparations preserved in the Museum, 
 as well as an entire specimen ; but I confess I cannot compre- 
 hend what the thing can be ; I am only clear that it is not a 
 Trematode worm. One might call it an arm torn from some 
 other Cephalopod, so similar is the double series of suckers oc- 
 cupying the ventral surface of the Hectocotylus to the larger 
 suckers of the Octopus : the internal structure is equally mus- 
 cular, but there is visible in the dorsal portion a long white 
 sinuous and folded thread, which Cuvier could detect only after 
 the action of spirit, and which therefore should proceed from 
 the coagulation of some liquid (spermatic?) substance " 
 
 " It can only be by the study of these objects in the living 
 state that we can decide upon their true nature, and determine 
 if they be not the portions of some Cephalopod detached in order 
 
 * Note sur le pretendu parasite de I 'Argonauta Argo (Ann. d. Sc. Nat. 
 2 f serie, t. xvi. 1841). 
 
 t Dujardin, Histoire Naturelle des Helminthes ou Vcrs Intestinaux (Suites 
 a Buff on, 1848). 
 
122 VERANY AND VOGT ON THE HECTOCOTYLI 
 
 to subserve fecundation. I can only state, that the long white 
 thread described by Cuvier, whose length is more than a metre, 
 is merely a bundle of very long and delicate, independent fila- 
 ments, closely resembling the spermatozoa of the Cephalopoda." 
 
 M. Kolliker, who during his stay at Messina in 1842 found 
 upon many female Argonauts the Hectocotylus described by M. 
 Delle Chiaje, originated a new r epoch in the history of this ani- 
 mal. M. Kolliker discovered in addition a new species of Hec- 
 tocotylus upon the Tremoctopus violaceus, and obtained some 
 fifteen specimens of it. In examining their structure he very 
 soon convinced himself, to use his own words, that these sup- 
 posed worms are nothing more than the males of the Cepha- 
 lopoda we have just mentioned. 
 
 After having communicated his ideas upon this subject to the 
 Italian Scientific Congress, sitting at Genoa, M. Kolliker pub- 
 lished a note in the ' Annals of Natural History,' vol. xvi. 1845. 
 The Manual of Comparative Anatomy, by M. von Siebold, being 
 in course of publication at the same time, M. Kolliker entrusted 
 three specimens of his treasure-trove to M. von Siebold, accom- 
 panying them with a manuscript note containing the results of 
 his observations. Upon his part M. von Siebold examined the 
 Hectocotyli, and, while confirming many of the conclusions of 
 M. Kolliker, he differed from him with respect to other points 
 of structure. Notwithstanding these discrepancies, M. von 
 Siebold adopted the views of M. Kolliker, who considered these 
 Hectocotyli to be the males of the Octopods upon which they 
 are found. The observations of M. von Siebold are contained 
 in his excellent ' Comparative Anatomy of the Invertebrata*/ 
 which is now also extensively circulated through France in a 
 good translation. Lastly, M. Kolliker published a very elabo- 
 rate memoir, accompanied with figures, in his Second Report of 
 the Zootomical Institution at Wurzburg, for the year 1849f. 
 
 M. Kolliker begins by describing at length the form of the 
 Hectocotylus of Tremoctopus violaceus, specimens of which he 
 met with upon almost all the females of this Cephalopod, which 
 he found in August and September at Messina. He distin- 
 
 * Lehrbuch der vergleichenden Anatomic der Wirbellosen Thiere ; von C. Th. 
 von Siebold. Berlin, 1848. 
 
 f Bericht von der Koniglichen zootomischen Anstalt zii Wurzburg. Leipzig, 
 1849. 
 
AND THE MALES OF CERTAIN CEPHALOPODS. 123 
 
 guishes externally two sets of suckers, branchiae in the form of 
 villosities, and an oval abdomen from whose aperture the penis 
 makes its exit. The skin is composed of two layers; of an epi- 
 dermis with polygonal cells, and of a corium composed of inter- 
 woven undulated fibrils, in the midst of which contractile pig- 
 ment-cells are deposited chromatophora such as are met with 
 in all Cephalopods, without exception. The muscular system is 
 composed of bundles belonging to the suckers, and besides of a 
 very strong muscular tube, which serves as a support to the 
 whole body, and in the interior of which is found a cylindrical 
 cavity almost entirely filled by a longitudinal tube which M. Kol- 
 liker calls the intestine. The muscular tube itself is composed 
 of three layers of fibres, the median being longitudinal, whilst 
 the other two are circular. M. Kolliker is unable to give any 
 complete account of the nervous system ; but having seen under 
 the microscope a true ganglion containing six ganglionic cor- 
 puscles, he is certain that nerves exist, and he believes that a 
 fine white thread, which he once met with upon the upper sur- 
 face of the intestine, is truly a nervous cord. M. von Siebold, 
 on the other hand, remarks, that he has found in the axis of the 
 body of the Hectocotylus of the Tremoctopus a nervous cord 
 whose greatly developed ganglia correspond in number with the 
 lateral suckers. M. von Siebold does not believe that the Hec- 
 tocotyli have any digestive system. M. Kolliker speaks doubt- 
 ingly : he describes a longitudinal tube situated in the centre of 
 the muscular tube, w r hich it almost wholly fills. This tube is 
 composed of two membranous layers ; according to his account 
 it is closed posteriorly, and terminates perhaps by a fine aper- 
 ture visible only in the recent animal and situated at its ante- 
 rior extremity. The tube contains nothing but conical masses, 
 arranged regularly, and exactly corresponding in number to the 
 suckers. M. Kolliker adverts also, as a supplement to this de- 
 scription of the intestinal system, to the existence of small ellip- 
 tical apertures arranged in line to the number .of four or five, 
 upon the ventral surface, below these conical bodies contained 
 in the intestine. These little apertures are prolonged into as 
 many fine canals which are directed upwards towards the central 
 muscular tube ; but he could not decide exactly if they entered 
 
124 VERANY AND VOGT ON THE HECTOCOTYLI 
 
 into the muscular tube to communicate with the conical bodies, 
 or if they were merely cutaneous glands. 
 
 We can easily satisfy the doubts of M. Kolliker upon this 
 matter. His so-called intestine is only a central blood-vessel ; 
 the conoid masses seen by him in this " intestine " are the 
 ganglia of the nervous cord situated below the vessel and not 
 within it ; whilst the canals with their fine apertures are only the 
 nerves passing from these ganglia and terminating in the skin. 
 The branchiae described by M. Kolliker are fine fringes com- 
 posed of an epidermis with polygonal cells ; and of a homo- 
 geneous internal membrane, in which a simple network of ca- 
 pillaries uniting into two very small trunks is placed. In 
 the skin of the back are found upon each side two longitudinal 
 vessels, with whose termination M. Kolliker was not acquainted, 
 but which appear to furnish branches for the penis also. Besides 
 these vessels, M. Kolliker found under the microscope, in a 
 fragment of skin with whose exact origin he was not acquainted, 
 an oval tube which he considered to be decidedly a heart, but 
 whose position he could not indicate. The generative organs 
 are very much developed ; they consist of a simple testicle, of 
 an ejaculatory duct, and of a penis. The testicle is a transpa- 
 rent pyriform vesicle, which fills the whole of the abdomen of 
 the Hectocotylus. In the interior of this vesicle there exists 
 coiled up a fine cylindrical thread, without any proper enve- 
 lope, and formed solely by filiform spermatozoa united together. 
 Beside these spermatozoa, granular cells are found in very 
 considerable number. This thread ends freely at its posterior 
 extremity ; but anteriorly it is continued forwards into the effe- 
 rent canal which commences by a clavate extremity, folds back 
 at first in the testicular vesicle, and finally passes into the penis. 
 The efferent canal has a very peculiar structure, for its parietes 
 are very solid, semi-transparent, yellowish, and composed of 
 elastic fibres. The anterior part of the efferent canal is situated 
 in the penis itself, and is traversed in its whole length by a 
 spiral ligament, whose nature M. Kolliker could not determine. 
 
 M. von Siebold describes the posterior extremity of the Hec- 
 tocotyli as a generative sac, in w r hich the seminal mass, with the 
 copulatory organ, and the efferent canal (provided with horny 
 
AND THE MALES OF CERTAIN CEPHALOPODS. 125 
 
 tubercles in its interior, which are everted during copulation), 
 which is continued into the penis, are contained. M. Kolliker 
 describes these tuberculosities as little conical spines. 
 
 Besides the Hectocotylus Tremoctopodis, M. Kolliker describes 
 and figures that of the Argonaut, which is distinguished from 
 the former by the absence of branchiae, of a sac-like abdomen, 
 of a free penis, and by the presence of a filiform appendage 
 which passes from the anterior extremity of its body. At the 
 base of this appendage two triangular membranous lobes are 
 placed. 
 
 The anatomical structure of this animal differs only in the 
 structure of the filiform appendage and in that of the sexual 
 organs. The filiform appendage is the continuation of the mus- 
 cular tube forming the axis of the body. The testicular capsule 
 is elongated and lined with pig rent-cells, which are probably 
 contractile. The testicle itself is formed by a spermatic thread 
 coiled up, and surrounded by a structureless membranous enve- 
 lope. The efferent duct leads into a silvery cylindrical tube, 
 which is probably the penis, and which is certainly of a mus- 
 cular nature. 
 
 M. Kolliker adds to this description of the Hectocotyli a long 
 dissertation, in which he sets forth the opinions of his prede- 
 cessors, as well as his own, the latter amounting to this, that the 
 Hectocotyli are the stunted males of certain speciesof Cephalopoda. 
 " There is no need (he says) for any lengthy evidence that the 
 Hectocotyli are independent animals. He who has not seen, as 
 MM. Laurillard, Delle Chiaje, and I have done, their lively, 
 independent, and continued movements, will not take them 
 for portions of Cephalopods, and still less for spermatophora, 
 if he considers their complicated organization, and if he calls 
 to mind that they have a heart with vessels, branchiae, nerves, 
 and such well-developed generative organs." In the face of this 
 positive assertion of M. Kolliker, we shall undertake to prove 
 that the Hectocotyli are, however, nothing more than detached 
 arms of Cephalopods, merely organized in a special manner. 
 
 After having shown that we were still unacquainted with the 
 male of the Argonaut and with that of the Tremoctopus, M. Kol- 
 liker brings forward, first, the resemblance of structure between 
 the Hectocotyli and the Cephalopoda ; he finds that the suckers, 
 
126 VERANY AND VOGT ON THE HECTOCOTYLI 
 
 * 
 
 the chromatophora, and the muscular tube of the Hectocotyli, are 
 constructed in exactly the same manner as the corresponding 
 portions of the Cephalopods, and that they are met with exclu- 
 sively among the latter animals. The presence of arteries and 
 veins, of a heart, and of branchiae, as well as the histological ele- 
 ments, are clearly opposed to the union of the Hectocotyli with 
 the intestinal worms. Lastly, M. Kolliker relies upon the ob- 
 servations of Madame Power and of M. Maravigno at Catania, 
 from which it would result that the Hectocotyli are formed as 
 such in the egg, and that they then resemble a little worm, pro- 
 vided in its whole length with two series of suckers, with a fili- 
 form appendage at one of its extremities, and a little enlarge- 
 ment towards the other. From all this M. Kolliker concludes 
 that the Hectocotyli are perfect animals ; and M. von Siebold has 
 completely adopted this view, although this conscientious ob- 
 server was able to discover neither the intestine nor the heart 
 pointed out by M. Kolliker essential organs, however, upon 
 whose existence depends in great measure the opinion of these 
 two naturalists. 
 
 In the meanwhile one of us had been employed in collecting, 
 for many years past, materials which promised another solution 
 of the problem. In his work upon the Cephalopoda of the 
 Mediterranean, M. Verany relates, p. 128, that in 1836 he met 
 with an Octopus., the description of which he published under 
 the name of Octopus Carena. The captured individual possessed, 
 instead of the right arm of the third pair, a vesicle seated upon 
 a little pedicle provided with some acetabula. Upon many 
 individuals collected after this period M. Verany observed, as of 
 constant occurrence, that this same arm was always abnormally 
 developed, and that most frequently the pedicle carried instead 
 of a vesicle, a very large arm terminated by an oval globe, and 
 having the form of the Hectocotylus of Cuvier. Our friend 
 F. de Filippi, Professor at Turin, did in fact recognize this 
 arm to be the Hectocotylus ', M. Verany having submitted to 
 MM. Filippi and Leydig (of Wurzburg), the latter a pupil of 
 M. Kolliker, a specimen of T. Carena preserved in spirits of 
 wine ; this arm became detached by the least force, leaving a 
 perfectly clean surface, whilst another arm could only be torn 
 off by violence. The observers having opened the little terminal 
 
AND THE MALES OF CERTAIN CEPHALOPODS. 
 
 sac, saw the white thread which terminates the Hectocotylus 
 make its exit, like that of the Argonaut. M. Verany drew the 
 following conclusions from these observations: " The Hectocotylus 
 of the Octopus is only a caducous arm of the Cephalopod ; this 
 arm carries the male organs, and in all probability these organs 
 are periodically developed. The Hectocotyli of the Argonaut and 
 of the Tremoctopus differ from that of the Octopus. The Hecto- 
 cotyli of the Argonaut and of the Tremoctopus cannot be the 
 arms of the Octopus which carries them, since they are infinitely 
 smaller, and since, so far as I am aware, these Cephalopods 
 have never been found with an arm wanting." 
 
 Dr. H. Miiller of Wurzburg visited the coasts of Sicily in 
 1850, with the intention of studying these contradictory facts. 
 He communicated orally to one of us during his passage to 
 Genoa, that having one day met with a very small Argonaut 
 carrying a vesicle, lie had taken this individual for an embryo 
 still retaining its umbilical vesicle, but that on counting the 
 arms he observed there w r ere only seven, and that the eighth 
 was replaced by this vesicle carried upon a little pedicle. Calling 
 to mind the facts observed in the Octopus, Dr. H. Miiller exa- 
 mined the animal which had come into his possession, and 
 found that this little creature which he had taken for an embryo 
 was in fact the perfect male of the Argonaut, and that the 
 Hectocotylus was hidden within the pedunculated vesicle. We 
 still await the publication of the observations collected by 
 Dr. Miiller. 
 
 As the foregoing extracts show, science has been loaded with a 
 number of observations and opinions but little concordant with 
 one another. Very desirous of obtaining a positive solution of 
 a question which appeared to us to possess the highest interest, 
 we united our efforts to procure a sufficiency of materials, and 
 to study them during life. Fishermen were instructed by the 
 one of us who could best make himself understood in the patois 
 of the country, and the Cephalopods brought to the market in 
 Nice were carefully scrutinized each day. The specimens, which 
 were very rare, of Argonauts and Tremoctopods which fell into 
 our hands, were the object of our minute but fruitless investi- 
 gations. We could not find a single Hectocotylus, although one 
 of us during a residence of two years at Nice examined seven 
 Argonauts and three females of Tremoctopus violaceus. 
 
128 VERANY AND VOGT ON THE HECTOCOTYLI 
 
 We were in despair, when, in April of this year, the males of 
 Tremoctopus Carena appeared all at once in very great numbers. 
 We give in the following pages the results of our common 
 studies, observing, however, that M. Verany especially occupied 
 himself with the zoological portion, whilst M. Vogt principally 
 took charge of the anatomical investigations. 
 
 I. Zoology. 
 TREMOCTOPUS CARENA. Tremoctopus Carena, Verany. Poulpe 
 
 Carena. Octopus Carena, Verany. Mem. de V Academic Royale 
 
 des Sciences de Turin, 2 e serie, t. i. pi. 2. 
 
 Monographic des Cephalopodes de la Mediterranee, p. 34 & 128, 
 pi. 14. figs. 2 & 3 ; pi. 41. figs. 1 & 2. 
 
 Body sac-like, provided with a constrictor apparatus. Head 
 compressed; eyes large and projecting. Arms unequal: first 
 and fourth pair longest. Acetabula pedunculated. Funnel very 
 large ; two aquiferous apertures. 
 
 Tremoctopus Carena, male (PI. I. fig. 3. 4.). 
 
 Body sac-like, oval, slightly acuminated behind, very smooth. 
 Branchial aperture wide, cleft as far as the orbits. Constrictor 
 apparatus formed by a fleshy appendage having the form of an 
 oblique hook, situate upon each side at the base of the funnel, 
 and a horizontal cleft like a button-hole, in the thickness of the 
 skin upon the internal margin of the body. 
 
 Head moderate, wider than deep, being compressed by the 
 first pair of arms w hich arise at the level of the orbits ; lateral 
 part of the head occupied almost wholly by the orbits ; inferior 
 portion wholly covered by the funnel. 
 
 Eyes lateral ; eye-balls projecting and flattened, wholly covered 
 by a transparent membrane which is continuous with the skin ; 
 this membrane is pierced by a slightly contractile circular aper- 
 ture, through which the crystalline lens presents itself wholly 
 without covering. 
 
 Arms conico-subulate, unequal ; the fourth pair is the longest 
 and measures about two and a half times the length of the body; 
 the first is shorter than the fourth and measures only twice the 
 length of the body ; the second is only half as long as the fourth 
 pair ; the left arm of the third pair is a little shorter than that of 
 the second pair ; the right arm of the third pair is hectocotyli- 
 
AND THE MALES OF CERTAIN CEPHALOPODS. 129 
 
 form, and has a pedicle equal in size to the base of the arm of 
 the opposite side ; this pedicle carries a larger or smaller oval 
 vesicle (PL I. f. 4.), containing the hectocotyliform arm or the per- 
 fectly developed Hectocotylus itself; this hectocotyliform arm is 
 half as long again as the arms of the fourth pair. All the arms 
 are provided with a double series of acetabula. 
 
 Acetabula : these are large, cylindrical, much excavated, pe- 
 dunculate, and distant from one another (PL I. fig. 3.); they alter- 
 nate from the third, enlarge up to the sixth, and afterwards de- 
 crease progressively as far as the extremity of the arms where 
 they are microscopic. The first pair of arms carries forty- five 
 acetabula ; the second, thirty ; the third, thirty ; the fourth, fifty. 
 
 The Hectocotylus is inserted upon a pedicle from which it is 
 readily detached (PL I. fig.3.) ; it is oval below and narrows towards 
 its extremity, which appears as if truncated ; the internal sur- 
 face is flattened, and its whole contour is beset with a very close 
 series of pedunculated acetabula which are oblique, i. e. have an 
 oval section opening a little upon the inner side. These acetabula 
 are united together by a longitudinal membrane which embraces 
 the whole peduncle, and, with the acetabula, forms a continuous 
 line by passing over at the base upon the inner surface of the 
 arm. Generally a little ovoid sac terminates the Hectocotylus. 
 This sac is transparent, and allows a convoluted cord to be seen 
 through its membrane ; the sac is frequently empty, and then 
 the hectocotyliform arm is terminated by a filament or flabellum 
 almost as long as the arm (PL I. fig. 3.), and which is its conti- 
 nuation. The Hectocotylus carries forty-seven acetabula upon 
 each side. The dorsal part is a little convex upon its base ; this 
 convexity is markedly distinguished by a membranous sac open 
 below (PL I. fig. 3.). 
 
 Interbrachial membrane rudimentary, absent between the 
 lower arms. 
 
 Mouth surrounded by two lips, the internal ciliated, the ex- 
 ternal very delicate. 
 
 Funnel very large, extending far beyond the base of the arms, 
 and measuring three-fourths of the length of the body. Two 
 very large aquiferous apertures, placed at the base of the arms of 
 the fourth pair at the point of attachment of the latero- dorsal 
 portion of the funnel and communicating with the orbital cavity. 
 Excluding the hectocotyliform arm, this Cephalopod is never 
 
 SCIEN. MEM. Mrt, Hist. VOL. I. PART II. 9 
 
130 VERANY AND VOGT ON THE HECTOCOTYLI 
 
 more than 0*110 (metre) in length ; taking in this arm and its fla- 
 bellum, it measures 0*220 (metre). 
 
 Colour. During life this Cephalopod has a general transpa- 
 rency which allows the internal organs to be seen through the 
 body, and in the lower parts, even the chromatophora which 
 cover the membrane investing the organs of digestion and gene- 
 ration, and along the arms, the beaded nervous cord. When at 
 rest, the body glistens with iridescent hues of azure, green and 
 purple ; the pupil is of a very brilliant burnished silver, and the 
 dorsal portion of the orbits has a brilliant blue tint shot with a 
 metallic golden tinge. The chromatophora are visible only 
 with a lens, and have a purplish (mauve) tint passing into 
 violet; when they dilate they are purple, and by the develop- 
 ment of a great number of chromatophora the dorsal surface 
 often passes into a velvety purple. When the creature is irri- 
 tated or out of the water, the chromatophora take an orange-red 
 tinge upon the lower portion ; the points are constantly larger 
 and more scattered than upon the upper. The funnel and the 
 membrane which invests the eyes are equally covered with them. 
 In spirit the chromatophora have always a wine -red colour ; in a 
 saline solution they retain their violet colour. 
 
 The Hectocotylus is wholly white, without chromatophora: 
 the pedicle which carries it and the vesicle in its interior are 
 covered with them. 
 
 Tremoctopus Carena, female. 
 
 Body sac-like, oval, smooth superiorly, very slightly tubercu- 
 lated below. Branchial aperture and constrictor apparatus as 
 in the male, 
 
 Arms conico-subulate, symmetrical ; length as in the male. 
 The first pair is provided with a longitudinal membrane upon its 
 latero-superior portion, and the acetabula of the internal series 
 are united together by a longitudinal membrane, as is observed 
 also in the reticulated Tremoctopus and in the Argonaut. 
 
 Acetabula moderate, cylindrical, excavato-pedunculated, but 
 little distant from one another ; the first pair has eighty of them, 
 the second seventy, the third sixty, the fourth eighty. 
 
 Interbrachial membrane, mouth, funnel, and aquiferous aper- 
 tures as in the male. 
 
AND THE MALES OF CERTAIN CEPHALOPODS. 131 
 
 Colour. During life and in a state of rest the dorsal part of 
 the animal is of a semi-transparent white colour, strongly shaded 
 with blue ; the inferior portion is white and very iridescent ; the 
 lateral parts of the body, of the head, of the dorsal portion of 
 the inferior and latero-inferior arms, and the iris shine with a 
 silvery lustre ; the internal portion of the arms is of a pale rosy 
 colour. In this state the dorsal portion is covered with micro- 
 scopical chromatophora, and with others which are larger and 
 regularly diffused, of a blue or violet colour ; upon the lower 
 portion of the body the chromatophora are disposed in the same 
 manner, but their colour is violet passing into reddish yellow. 
 The dorsal part of the body, of the head, and of the arms of 
 the first pair assumes sometimes a very brilliant ultramarine 
 colour, shaded with purple ; sometimes this passes into a very 
 dark velvety violet ; the lower parts and the extremities of the 
 arms are then coloured reddish yellow. Three different colours 
 are often seen upon the back at the same time, and it is clouded 
 with white, azure, rose-violet, yellow, and an infinity of dazzling 
 shades produced by the mixture of these tints. Irritated, or in 
 full vigour out of water, the animal covers itself wholly with 
 reddish yellow chromatophora, but the dorsal portion is always 
 strongly shaded with blue. Plunged in spirit, the skin of the lower 
 partof the body becomes very finely reticulated, in consequence of 
 the wrinkles formed by the subcutaneous granulated tubercles. 
 
 The male Tremoctopus Carena cannot be confounded with any 
 of the known species ; the proportions of the arms, and, above 
 all, of the hectocotyliform arms, clearly distinguish it. The 
 female closely approaches the reticulated Tremoctopus (T. cate- 
 nulatus, Ver.), but the arms of T. Carena are much longer in 
 proportion to the body, and the second and third pairs of its 
 arms are comparatively shorter and less disproportionate to one 
 another in size. The body is oval, while it is ovoid in T. cate- 
 nulatus ; finally, the tubercles are proportionally much smaller, 
 more approximated and more numerous in T. Carena. 
 
 This Cephalopod appears only accidentally upon our coasts, 
 perhaps, as M. d'Orbigny thinks with regard to all the Philo- 
 nexida, because it is pelagic; we have, however, met with it in 
 all seasons, in February, April, September and December, which 
 proves to us that it is a denizen of our latitudes. It is always 
 
 9* 
 
132 VERANY AND VOGT ON THE HECTOCOTYLI 
 
 taken near land by means of drag-nets. Professor Bellardi of 
 Turin, who was at Nice in April of this year, assured us that 
 having been present at the raising of the Madrague nets*, he saw 
 one of these Octopods attached to a dead Salpa. The Octopus 
 evidently approaches the shore at the pairing season, and it is 
 to this cause, as well as to the arrangements we made, that we 
 owe the capture of twenty males and two females which were 
 all taken last April. All the specimens have been brought to us 
 living : a single male had lost its hectocotyliform arm ; all the 
 others presented this arm either wholly developed or still in- 
 cluded within its vesicle. The male by itself has been described 
 and figured since 1846 in the Acts of the Royal Academy of 
 Sciences of Turin, by one of us, and later in the Monographic 
 des Cephalopcdes de la M edit err anee which has just appeared. 
 The female has perhaps been described by M. Risso under the 
 name of Octopus tuberculatus, but the short phrase applied to 
 this new species is so vague and diffuse, that it may equally 
 relate to the Tremoctopus catenulatus. M. Risso having left no 
 specimen marked by himself by which it might be decided to 
 which of the two species his description refers, we must retain 
 the name given by one of us in 1836; and so much the more 
 since M. d'Orbigny has already designated Octopus tuberculatus, 
 another species of Octopus previously described by M. de 
 Blainville. 
 
 M. d'Orbigny does not mention our T. Carena in his Mono- 
 graph upon the Cephalopoda. It is very remarkable that this 
 species, which this year was so frequently taken, and which be- 
 sides does not appear to be very rare, should have escaped Delle 
 Chiaje, whp has enriched science with so many new species ; 
 Prof. Philippi,who has so carefully explored Sicily; M. Cantraine, 
 who has traversed a large portion of the Mediterranean ; as well 
 as MM. Kolliker, Riippell, Krohn, and H. M'uller, who have 
 specially occupied themselves with the Cephalopoda in Sicily. 
 However, we have reason to believe that the Octopus granulosus, 
 upon which Laurillard found the Hectocotyli which were de- 
 scribed by Cuvier, is the female of the species with which we are 
 engaged. 
 
 * Large nets employed in the tunny fishery, established permanently near 
 St. Hospice, a league from Nice. 
 
AND THE MALES OF CERTAIN CEPHALOPODS. 133 
 
 II. Anatomy. 
 
 We shall first treat of the anatomy of the male, whose orga- 
 nization in general does not differ, in fact, from that of other Ce- 
 phalopods. The ventral region of the mantle is provided with a 
 very complicated constrictor apparatus, fixed to the fibrous mem- 
 brane which invests the intestine. After having cleft the mantle 
 longitudinally (PI. II. fig. 1.), we observe the branchiae, each with a 
 branchial heart situated at its base, and not differing in structure 
 from those of other Octopods. During life, however, these 
 branchiae exhibited great contractility, and the branchial hearts, 
 whose function has been questioned, pulsated regularly. The 
 fibrous membrane which invests all the intestines is covered, 
 especially below, with numerous chromatophora, which contract 
 and dilate alternately. We see across this membrane the vaguely 
 marked contour of the last portion of the intestine, of the ink- 
 bag and of the genitalia which occupy the posterior portion of 
 the body. The conjoint aperture of the rectum and of the ink- 
 bag is placed upon a little muscular tongue which ends forwards 
 in two very fine points, and which passes so far forwards below 
 the funnel that the posterior edge of the latter covers it com- 
 pletely. At first we sought in vain for a long time for the aper- 
 ture of the generative organs, which is perceived with great dif- 
 ficulty, when an accident discovered its position. One of the 
 specimens which we were examining presented through the 
 mantle a streak of white matter which began to fill the branchial 
 cavity. Having carefully opened this individual, we saw a coil 
 of the seminal thread, which we shall describe by- and- by, escape 
 from a semilunar aperture upon the left side, by the side of the 
 place where the branchial vessels leave the intestinal sac to pass 
 into the branchia. It was afterwards easy to perceive this very 
 much contracted cleft in all specimens, and to convince ourselves, 
 by examining the internal generative organs, that this asymme- 
 trical orifice was the sole means of discharging the contents of 
 the generative organs into the branchial cavity. 
 
 After having taken away the fibrous intestinal sac (PI. II. fig. 1.) 
 we easily discover the rectum, which is very delicate, passes 
 from below upwards from the dilatation of the large trunk, and 
 which rises among a considerable mass of venous appendages 
 
134 VERANY AND VOGT ON THE HECTOCOTYLt 
 
 which especially invest the aortic heart and the great vessels 
 uniting the latter with the branchiae. Below this mass of venous 
 appendages we see a flask-shaped organ of a gelatinous trans- 
 parency, and through which fine silvery lines may be distin- 
 guished ; these have a very peculiar lustre, and look like white 
 lights painted thickly and with great brilliancy upon a grayish 
 satin ground. These lines differ much in their arrangement in 
 different specimens ; we see, however, that they are especially 
 numerous towards the posterior convex edge of the flask, whilst 
 the anterior hollowed border of this organ seems to contain a 
 more transparent substance. The bottom of the flask, whose 
 form varies very much in consequence of the great contractility 
 which it possesses, is turned to the right, while its narrowed 
 neck passes to the left upon the great vessels of the branchia. 
 This extremity hooks round these vessels, and at the summit of 
 the curve is found the cleft orifice of which we have spoken 
 above. 
 
 The remainder of the generative apparatus (PL II. fig. 4.) is 
 situated upon the dorsal surface of the intestinal sac, and is con- 
 tinuous with the neck of the flask. It is composed of an elongated 
 vesicle having nearly the same form as the flask, and possessing 
 as great contractility in its transparent muscular parietes. It 
 is divided into two portions, which however are united in a 
 common envelope. The anterior portion we will call the cornu : 
 it is membranous and transparent, and allows a contained 
 whitish spiral thread to be seen through its side, much less 
 brilliant and larger than the threads contained in the flask. At 
 the posterior enlarged extremity of the cornu there is attached 
 an organ having the form of a pointed apple, whose base is 
 turned towards the cornu, its point towards the right branchia, 
 with the heart corresponding to which it is in contact. This 
 organ has a yellowish chalky tint ; its internal surface is strongly 
 attached by cellular tissue to the base of the flask ; it is the 
 testicle. The generative organs thus form altogether an actual 
 ring (PL II. fig. 3.) round the great vessels of the left branchia ; a 
 ring which is completed behind only by the fibrous tissue uniting 
 the envelope of the testicle to the bottom of the flask, whilst the 
 closure of the ring in front, upon the ventral face, is produced 
 by the union of the neck of the flask with the neck of the cornu. 
 
AND THE MALES OF CERTAIN CEPHALOPODS. 135 
 
 We have just pointed out the form of the testicle ; besides the 
 general envelope which unites this organ to the cornu, it has a 
 proper fibrous envelope which closely invests it. Invariably 
 situated upon the dorsal surface, behind the branchial heart of that 
 side, the testicle however changes its place more or less, according 
 to the state of turgescence of the different portions of the sexual 
 apparatus. The testicle itself is divided into two portions which 
 differ in appearance even to the naked eye ; the pointed extre- 
 mity being more transparent than the body of the organ which 
 is turned towards the cornu. Fine chalky lines radiate from 
 the pointed extremity in all directions towards the enlarged 
 centre of the organ, where they converge again to approach that 
 face of the testicle which is in contact with the cornu. Under 
 the microscope these chalky lines are seen at once to be the 
 seminiferous tubes which end in a cul de sac at the pointed 
 extremity of the testicle, and which begin to ramify when they 
 enter into the thick portion of this organ. These ramifications 
 however are almost parallel with one another, so that the entire 
 testicle seems to be composed of parallel seminiferous tubes, 
 which however converge both towards the point and towards the 
 base of the organ. 
 
 The seminiferous tubes contained, in all the individuals we 
 examined, no trace of completely developed spermatozoa, but 
 only granular cells and very small free granulations, which from 
 their strongly -marked contour had the appearance of fine drops 
 of oil ; the granule-cells also exhibited among the fine granules 
 more strongly-marked little drops. All the individuals which 
 we examined being in the pairing season, the spermatozoa had 
 already passed into the ejaculatory organs, and in the semini- 
 ferous tubes of the testicle there were found only the elements 
 required for the reproduction of the semen. 
 
 There is no direct connexion between the seminiferous tubes 
 and the efferent canal; we have assured ourselves of this cir- 
 cumstance microscopically. The special envelope of the testicle 
 (PL III. fig. 5.) is considerably narrowed at the base of that organ, 
 and is directly continued into the muscular envelope of the cornu. 
 A kind of funnel is thus formed at the place where the testicle is 
 attached to the cornu, towards which all the seminiferous tubes 
 converge to terminate by a rounded end. The contents of these 
 
136 VERANY AND VOGT ON THE HECTOCOTYLI 
 
 tubes ought then to be poured into the space formed by this funnel, 
 which is nothing more than the continuation of the special enve- 
 lope of the testicle. The seminal masses would, by means of this 
 funnel, pass freely into the bottom of the cornu, if there were not 
 a very narrow deferent canal (PI. III. fig. 5 ri), which is affixed 
 to the funnel like a tube, and projects freely into the cavity of 
 the cornu. Merely looking at the cornu, this canal may be seen 
 applied to its dorsal surface; it is about 3 millimetres long; 
 and even without opening the cornu, it is easy to convince one- 
 self with a lens that its free extremity floats in the cavity of the 
 cornu. This canal is extremely contractile and mobile, and has 
 almost continually during life a vermicular motion. The struc- 
 ture of the canal is very simple : it is a muscular tube, with its 
 longitudinal fibres especially developed, united into bundles and 
 so forming slightly projecting ridges upon the internal surface 
 of the canal. The orifice of the canal resembles the mouth of a 
 hydroid polype, in consequence of these radiating ridges. The 
 whole internal surface of the canal is covered with cilia of such 
 large size, that the single ones can be distinguished with a 
 magnifying power of 100 diameters, whilst the movement itself 
 and the current produced by it are very distinctly visible by the 
 very lowest powers. It is evident, from the disposition and 
 structure of this efferent canal, that the seminal mass, entering 
 the funnel in consequence of the rupture of the seminal tubes, 
 is received by the efferent canal, and conducted by the latter 
 into the cavity of the cornu, which thus in some respects serves 
 as a seminal reservoir. 
 
 The structure of the cornu itself is very complicated, and we 
 should have had considerable doubt as to certain points of its 
 anatomy, if chance had not given into our hands many living 
 animals in succession, upon which we were enabled to complete 
 our researches. We have already mentioned the white and 
 coiled thread which is visible across the transparent parietes 
 of the cornu ; this coil is constantly in motion, as well in con- 
 sequence of its own contractions as of those of the investment 
 of the cornu, w r hich is very solid and is formed by muscular 
 fibres interlaced in all directions. The coil is laid bare when 
 this contractile envelope is cut open : it swims, so to speak, in a 
 viscous liquid which fills all the cornu, and which glues together 
 
AND THE MALES OF CERTAIN CEPHALOPODS. 13? 
 
 all the folds of the coil, and that so effectually, that there is some 
 difficulty in disentangling them. When the attempt has been 
 successful, we see that the coil is obviously composed of two 
 filiform organs rolled up together, i . e. of the deferent canal and 
 of an accessory gland, whose excretory canal is united to the 
 deferent canal towards the apex of the neck of the cornu. 
 
 The deferent canal (PI. III. fig. 5 d') begins by a trumpet-shaped 
 orifice (PL III. fig. 5 i) folded like the orifice of the efferent canal, 
 but wider than the latter ; this orifice is not clothed with vibratile 
 cilia, like the efferent canal, which tends to confirm our observa- 
 tion, that the two canals have no direct communication with one 
 another. The plaited orifice of the deferent canal becomes conti- 
 nued into a considerable dilatation of a pear-shape (PI. III. fig. 5 g) 
 whose wider extremity is turned towards the orifice, while the tail 
 a little enlarged passes into the continuation of the deferent canal ; 
 this dilatation is produced less by any enlargement of the cavity 
 of the canal than by the very considerable development of the 
 muscular layer, which forms very projecting longitudinal ridges 
 at this place, converging towards the pointed extremity of the 
 dilatation. Besides this greatly-developed muscular structure, 
 we see, as an appendage to the pyriform dilatation, a perfectly 
 rounded bag (PI. III. fig. 5 h) which pours its contents by means 
 of a little excretory duct, where the plaited orifice is continuous 
 with the muscular dilatation. We could discover no histological 
 elements in this secretion, which was composed of a substance 
 resembling stearine. 
 
 The deferent canal is prolonged from the pyriform dila- 
 tation as a simple cylindrical canal. It possesses contractility, 
 owing to a muscular layer which principally forms the tube. 
 Two clavate enlargements succeed one another at a slight distance 
 from the pyriform dilatation, and are owing, like the latter, to a 
 greater development of the muscular layer. The interior of the 
 deferent canal is clothed through its whole length with a glairy 
 secretion, and most frequently the canal appears to be wholly 
 empty; we however met with one individual in which a seminal 
 mass was arrested before the first clavate enlargement. We 
 shall return to this chance-discovery, since it throws some light 
 upon the formation of the seminal machines in general. 
 
 In passing towards the pointed extremity of the cornu, the 
 
138 VEBANY AND VOGT ON THE HECTOCOTYLI 
 
 deferent canal makes a multitude of folds, united to those of 
 the accessory gland by very fine and very elastic fibres, which 
 while they unite them, allow of a very considerable amount of 
 contraction to each of these canals. At the extremity of the 
 cornu the deferent canal opens into a kind of common reservoir 
 which lies at the entrance of the cornu. 
 
 The accessory gland (PL III. fig. 5 m) which is enclosed in the 
 cavity of the cornu, with the deferent canal, is composed of two 
 portions, which, however, in their intimate structure present no 
 essential difference the gland itself and the excretory canal. The 
 gland is a flattened body rolled almost spirally, and exhibits 
 even to the naked eye a granulated appearance, resulting from 
 the presence of many minute points which are almost entirely 
 opake by transmitted light. The intimate structure of this gland 
 is very remarkable ; its parietes are very thick, and there is in 
 the middle of the gland a cavity which is directly continuous 
 with the excretory canal. Instead of glandular tubes, it consists 
 of little, more or less rounded sacs (PL III. fig. 8.), which are hol- 
 lowed in the very substance of the gland, and whose aperture is 
 almost as large as its base. These sacs beset the whole internal 
 surface of the gland and of its excretory duct ; they are merely 
 deeper in the gland than in the duct, and disposed a little more 
 obliquely with regard to the axis of the gland. They are imme- 
 diately surrounded by a very much developed elegant capillary 
 network. The proper walls of these sacs are very thick ; they 
 are composed of a small number of circular fibres, and are lined 
 internally with a considerable layer of cylindrical cells, carry- 
 ing at their extremity very long cilia ; these are in continual 
 movement, and they transport a viscous homogeneous liquid 
 containing fine granules, which are here and there united into 
 little masses. These glandular sacs, which doubtless secrete the 
 mass of which the envelope of the spermatic machines is formed, 
 are continued until close to the anterior extremity of the excre- 
 tory canal ; there they disappear by degrees, and the excretory 
 canal itself becomes considerably enlarged, to form a wide sac 
 (PL III. fig. 5 b) into which the deferent canal also opens. This 
 sac is on all sides attached to the parietes of the cornu, so that 
 the cavity of the latter is completely shut at this place, and thus 
 there is no other passage from the cornu to the flask than 
 
AND THE MALES OF CERTAIN CEPHALOPODS. 139 
 
 through the sac. We see then, that in consequence of the very 
 arrangement of the parts, the seminal masses carried by the 
 deferent canal ought to meet in this common reservoir with the 
 product of the secretion of the accessory gland, and to enter 
 with it into the flask. It is probable therefore that here, in this 
 wide sac with delicate walls, the spermatic machines are formed 
 and pass afterwards into the flask. 
 
 The latter organ (PI. III. fig. 1-4.) is situated, as we have al- 
 ready said, upon the ventral face of the intestinal sac immediately 
 under the fibrous envelope which surrounds the latter. The mem- 
 brane which forms the flask is very delicate, very contractile, and 
 almost impermeable to water. In its interior we see undulating 
 brilliant white lines, such as we have described above, and which 
 are sometimes so obvious that they might be taken for external 
 ornaments of the envelope. The semilunar aperture situated 
 close to the neck of the flask is generally very difficult to per- 
 ceive, and opens only after a prolonged stay in the water to give 
 exit to the contents of the flask, which are formed in all the in- 
 dividuals we have examined by a unique spermatic machine, 
 by a single spermatophore filling the whole cavity so completely, 
 that it is very difficult to open the latter without damaging the 
 spermatophore contained in its interior. 
 
 This enormous spermatophore (PI. IV. fig. 1.), which is nearly 
 two centimetres in length, is always folded up in the flask, so that 
 both its extremities approach the semilunar aperture of the latter. 
 Removed from the flask the spermatophore has the shape of a 
 powder-horn, having one extremity pointed and elongated into 
 a beak, the other enlarged and rounded. The beak, although 
 the more firm and consistent portion, is however almost trans- 
 parent, whilst the sac appears almost white, by reason of the 
 convoluted silvery thread which it contains in its interior. The 
 spermatophore itself is formed by a very solid membrane, per- 
 fectly transparent, which, after having formed the sac, is con- 
 tinued upon the beak-like prolongation, surrounding it very 
 closely. This envelope absorbs water very quickly, and swells 
 out rapidly in consequence; it becomes separated then into two 
 layers, the exterior of which, very delicate, forms irregular folds, 
 often so multiplied that one might imagine the beak of the sper- 
 matophore to be constituted here and there by the convolutions 
 
140 VERANY AND VOGT ON THE HECTOCOTYLI 
 
 of a fine spiral thread. The proper coat which lies below this 
 layer becomes distended by the action of water, very much as a 
 gummy mass would be, and finally bursts to allow the passage 
 of the contents of the spermatophore. 
 
 These contents are composed of two very dissimilar threads; 
 the one belonging especially to the beak-like prolongation, the 
 other to the sac of the spermatophore. We call this last thread 
 the spermatic cord (PL IV. fig. 2 c), since it is wholly made up of 
 spermatozoa united together around a fine thread-like axis. This 
 spermatic cord is entirely white, silvery to the naked eye, and 
 of an even diameter throughout, except its anterior extremity, 
 where it becomes more delicate, to attach itself finally by an ex- 
 cessively delicate thread to the posterior extremity of the ejacu- 
 latory cord. The spermatozoa are united together in the sper- 
 matic cord in such a manner that their cylindrical end, which is 
 the larger, is attached, or rather glued by a viscous liquid, to the 
 axis of the cord, whilst their very fine caudal extremity is turned 
 towards the periphery. We can compare this structure to 
 nothing better than to the elongated brushes used for cleaning 
 bottles, in which the bristles radiate upon all sides from a me- 
 dian axis formed by an iron thread. The spermatic cord becomes 
 distorted very soon when it is subjected to the action of water, 
 and it is almost impossible to unroll its coils before the comple- 
 tion of this distortion. At the very moment the spermatic cord 
 is drawn out of its envelope, all the spermatozoa appear to be 
 united by a glutinous liquid, which connects them so closely that 
 it is impossible to distinguish them. By the action of water, 
 this glutinous mass at first dissolves a little ; the spermatozoa 
 become free, and appear then to be animated by slight undu- 
 latory movements. Little by little these motions cease, whilst 
 the glutinous matter congeals by the operation of the water, and 
 to such an extent that the spermatic cord soon looks like a felted 
 mass whose elements are undistinguishable. It seems probable 
 to us, that the irregularly nodulated appearance noticed by 
 Von Siebold upon the spermatic cord of the Hectocotylus Trem- 
 octopodis, proceeds from a similar alteration produced by the 
 influence of water. 
 
 We have said that the spermatic cord ends by a more delicate 
 extremity, when, forming numerous convolutions, it approaches 
 
AND THE MALES OF CERTAIN CEPHALOPODS. 141 
 
 the anterior extremity of the sac, where. the beak-like projection 
 of the spermatophore commences. In fact, the cord becomes 
 very delicate (PL IV. fig. 3 0), and finally attaches itself to the 
 posterior extremity of the ejaculatory canal, which in its turn 
 fills the beak-like projection of the spermatophore. This eja- 
 culatory canal is formed by a very firm tube with thick pa- 
 rietes, having only a very small canal in its interior. Its parietes 
 are excessively transparent, resist pressure greatly, and do not 
 become disfigured by the action of water. We have been quite 
 unable to discover any further structure in this homogeneous 
 tube, which commences in the sac of the spermatophore by a 
 rounded extremity, slightly drawn out, and having a minute 
 aperture into which the extremity of the axis of the spermatic 
 cord penetrates as a very fine thread repeatedly folded up in the 
 cavity of the ejaculatory canal. The latter widens very soon, 
 together with its internal cavity, which is filled in the whole 
 length of its course by a spirally folded membranous ligament. 
 We see distinctly in the posterior extremity of the ejaculatory 
 cord the commencement of this membrane, which clothes the in- 
 terior of the canal of the cord, and seems at first plaited into a 
 number of transverse folds, which by degrees assume a spiral 
 disposition, so that at last the end of the ejaculatory canal re- 
 sembles under the microscope the intestine of a shark with its 
 spiral valve (PL IV. fig. 4.). The ejaculatory canal forms at first 
 many folds in the wider portion of the beak-like prolongation ; 
 after which it becomes continued almost in a straight line, form- 
 ing itself the axis of the prolongation. At the extremity of this 
 prolongation may be distinguished the whole external envelope 
 of the spermatophore, which becomes bent back, so to say, to- 
 wards the interior to form the tube of the ejaculatory cord, whose 
 canal, clothed by the spiral membrane, is continued as far as 
 this extremity. 
 
 The analogy between the structure of the spermatophore which 
 we have just described and that of those of the other Cephalo- 
 poda with which we iiave long been acquainted is evident, so 
 that we need insist at no greater length upon this point. The 
 envelope which swells out by the action of water ; the ejaculatory 
 cord, with its internal spiral ligament; in all these points the 
 resemblance is complete, with this difference only, that the semi- 
 
142 VERANY AND VOGT ON THE HECTOCOTYLI 
 
 nal mass is not included in a sac as in the other Cephalopoda, 
 but is formed by a long cord coiled upon itself and completely 
 deprived of any special envelope. The formation of these semi- 
 nal machines, whose size is enormous relatively to that of the 
 male animal, is pretty well explained by an observation we made 
 upon one of the four individuals which we examined. A 
 whitish mass (PI. III. fig. 5/) was situated in the deferent canal 
 of this individual a little beyond the pyriform enlargement by 
 which this canal commences. It presented itself under the form 
 of a pear (PI. III. fig. 9.) with an elongated tail, containing 
 internally a thousandfold coil of a fine gelatinous, very transpa- 
 rent thread, beset on all sides with motionless spermatozoa. 
 This thread became lost by degrees in the more enlarged portion 
 of the mass ; and even by pressing aside the matted spermatozoa 
 forming it, one could only distinguish here and there some traces 
 of a similar gelatinous thread ; it was however by no means well 
 marked. This mass of spermatozoa was not invested by any 
 envelope, and it still retained the form of the foot-like enlarge- 
 ment in which it had been modelled. It seemed evident to us 
 that such a seminal accumulation is moulded by passing through 
 the whole length of the deferent canal into an elongated thread, 
 and that it is in the common reservoir that this thread receives 
 at once both its envelope and the ejaculatory cord secreted by 
 the accessory gland, which thus transforms the whole into a 
 spermatophore. This, once formed, passes into the flask, whence 
 it is expelled when copulation is about to occur. 
 
 In the great majority of individuals which we examined, the 
 right arm of the third pair was disproportionately developed, 
 and had an external organization such as we have pointed out 
 in our zoological description. In other individuals this arm was 
 replaced by a very considerable pedunculated vesicle. We shall 
 see by the anatomy of these parts that there exists a correlation 
 between them an intimate correlation and that the formation 
 of the vesicle must necessarily precede that of the hectocotyli- 
 form arm. 
 
 As to the latter, we have been unable to discover in its struc- 
 ture any great differences beyond those we are about to point out, 
 from that of an ordinary Cephalopod-arm. The axis of this arm 
 is formed by a cylindrical muscular tube of great thickness, 
 
AND THE MALES OF CERTAIN CEPHALOPODS. 143 
 
 which is continued beyond the series of acetabula into a long 
 filiform appendage which we name the " flabellum," and which 
 is ordinarily concealed in an ovate sac which terminates the 
 anterior extremity of this arm. This muscular axis is formed, 
 as M. Kolliker has already very well shown, of three different 
 layers, one of which is longitudinal and the other two circular. 
 In the midst there is a hollow cylindrical space, in which are 
 situated two organs which require the more careful examination, 
 since M. Kolliker has entirely mistaken their nature. One of 
 these organs is a blood-vessel with very delicate and transparent 
 parietes, which runs through the whole length of the muscular 
 axis even in the portion which we have called the flabellum, 
 without any great diminution of its volume. There can be no 
 doubt as to the exact nature of this vessel, which we have many 
 times observed by transmitted light in individuals still living, 
 but in which the movements of the heart were too irregular to 
 allow of our determining the direction in which the current of 
 the blood moved. We could very well distinguish the blood- 
 corpuscles, forming at the time of death irregular masses, which, 
 while the heart yet beat, were agitated more or less distinctly. 
 Unable to make any injection of the few specimens at our com- 
 mand, we could not correctly determine the relations between 
 this vessel occupying the central axis of the muscular cylinder, 
 and the cutaneous vessels which appear upon the whole surface 
 of the arm. We believe, however, that we have seen, towards 
 the anterior extremity of the flabellum, this central vessel giving 
 off lateral branches, which pierce the muscular tube to pass to 
 the external surface and to the skin. The vessel is continued 
 uninterruptedly into the pedicle of the arm, where we were un- 
 able to trace it further. It seems indubitable, however, after 
 what we have just said, that it is the central artery of this ab- 
 normal arm, disposed like the central arteries of the other normal 
 arms. 
 
 The second organ worthy of remark, and which is enclosed 
 in the muscular canal, is the nervous cord formed by as many 
 ganglia as there are acetabula upon the whole length of the arm. 
 The tissues of the living individuals are so transparent, that we 
 can perfectly well distinguish the nervous cord in all the arms 
 of these little males without any dissection, and all the ganglia 
 
144 VERANY AND VOGT ON THE HECTOCOTYLI 
 
 corresponding to the acetabula can be counted with the most 
 scrupulous exactness. It is equally easy to see this ganglionic 
 cord in the hectocotyliform arm, and to decide that, as M. von 
 Siebold has well observed, there is only a single ganglion cor- 
 responding to each acetabulum ; but the acetabula being very 
 closely approximated, and succeeding one another alternately 
 upon the two sides, the ganglia also are pressed against one 
 another, so that to the naked eye, or under a simple lens, they 
 look like the close beads of a necklace. Examined microscopi- 
 cally, these ganglia (PL IV. fig. 6 c) all show the form of a tra- 
 pezoid whose base is turned towards the acetabulum to which the 
 ganglion belongs. M. Kolliker has figured the appearance of 
 these ganglia pretty well ; but by an inconceivable mistake, he 
 regards the ganglia as masses forming the contents of the central 
 vessel which he makes out to be an intestine. The nerves pass- 
 ing from these ganglia are to be seen with great difficulty, inas- 
 much as they penetrate the muscular cylinder in such a manner 
 that they are almost always perpendicular to the microscope. 
 Hence M. Kolliker has described these nerves as canals ascend- 
 ing towards the surface of the skin ; and we must confess in fact, 
 that a little nerve viewed perpendicularly upon its axis is not 
 unlike a fine canal with delicate sharp parietes. 
 
 The chain of ganglia ends with the series of acetabula ; but 
 some nervous threads which are very delicate might yet be per- 
 ceived in the muscular axis of the flabellum, where they ended 
 by becoming so fine that it was impossible for us to trace them 
 to its extremity. 
 
 We find no differences whatsoever in the structure of the rest 
 of the arm, so far as there are suckers; the skin, the walls of 
 the acetabula and their whole structure appear to be entirely 
 conformable with all that we have seen in the arms of ordinary 
 Cephalopods : we may be allowed then to pass over these points 
 in silence. 
 
 The anterior extremity of the arm is formed by a little oval 
 sac, which hangs between the two last acetabula, and whose 
 wall is a direct continuation of the skin which covers the dorsal 
 face of the arms. On carefully examining this little sac, we 
 perceive even with the naked eye that its interior contains a spi- 
 rally coiled thread. Between the two last acetabula there exists 
 
AND THE MALES OF CERTAIN CEPHALOPODS. 145 
 
 a little fissure which leads into the cavity of this sac, and by 
 which the animal is enabled to evolve the spiral filament hidden 
 in its interior. We have frequently seen instances of this oc- 
 currence ; the filament passed by its pointed extremity out of 
 this cleft and slowly unrolled itself; the sac all the while being 
 agitated by repeated contractions which aided the expulsory 
 movement. The filament itself performs very marked vermi- 
 cular movements, which we can only compare to the motions of 
 the tentacular filaments of certain tubicolar worms, particularly 
 of the Terebella. The little sac is wholly contracted when the 
 thread has passed out of it, and it then exhibits under the mi- 
 croscope (PL IV. fig. 6 e,f) very numerous rugosities, presenting 
 a sort of very pretty watered pattern. It evidently consists of 
 tw T o membranes, one external, which is nothing more or less than 
 the continuation of the skin which covers the whole arm, and an 
 internal muscular layer which is continued by two muscular 
 bundles upon the two sides of the flabellum. This sac con- 
 tracted upon the flabellum, which it had contained, has been 
 also seen by the authors who have written upon the Hectoco- 
 tylus of the Argonaut; and lastly by M. Kolliker, who 
 regards it as a membranous appendage without any other sig- 
 nification. 
 
 The flabellum itself (PL IV. fig. 8) is composed especially, as 
 we have said above, of the muscular cylinder of the arm, whtc h 
 occupies its centre without interruption as far as its extremity, 
 gradually becoming smaller. This cylinder ends by a point at 
 the very extremity of the flabellum, which is at first completely 
 rounded, but becomes flattened little by little like a lance-head 
 towards its end. At the distance of a few millimetres from the 
 extremity of the flabellum the muscular cylinder becomes sud- 
 denly thickened, and takes the form of a piston (PL IV. fig. 8 b) ; 
 its internal cavity even is here widened. At this same place we 
 have always seen a considerable mass of blood-corpuscles dis- 
 tending the enlarged cavity. The median vessel which occu- 
 pies the centre of the muscular tube, ends therefore here in a 
 kind of reservoir, whilst the muscular axis continues as a hollow 
 cylinder as far as the extremity. The external membrane which 
 invests the flabellum is, especially at its base, very loose, and 
 exhibits proper undulatory movements due to two muscular bun- 
 
 SCIEN. MEM. Nat. Hist. VOL. I. PART II. 10 
 
146 VERANY AND VOGT ON THE HECTOCOTYLI 
 
 dies which run along the two sides of the flabellum, and which 
 may be followed even beyond the piston-like enlargement. These 
 two cutaneous muscles are accompanied through their whole 
 length by two venous trunks which send off numerous ramifica- 
 tions, forming a capillary network over the whole surface of the 
 flabellum. These ramifications are especially remarkable at the 
 very extremity of the flabellum, where they are perceived very 
 easily, the tissues being at this place completely transparent. 
 
 The extreme mobility of the flabellum perhaps plays a part in 
 the physiological functions of the hectocotyliform arm. We 
 have seen this appendage continually in movement, as if it were 
 feeling about to fix itself somewhere. It embraced the arms, 
 and even the body of the animal to which it belonged, but it 
 disentangled its coils again without its being possible to discover 
 to what end all these motions tended. We shall bring forward 
 by-and-by an observation of M. Kolliker's, which will, perhaps, 
 set other observers upon the track of the physiological function 
 of this part. 
 
 We have yet to mention a last peculiarity of the structure of 
 the hectocotyliform arm ; it is the existence of a sac of con- 
 siderable extent, which is visible upon the posterior or dorsal 
 face of the arm near its base, and therefore opposite to the ace- 
 tabula. This sac (PL I. fig. 3 a) is 15-20 millimetres in length, 
 and is elongated, inasmuch as it lies along the dorsal face of the 
 muscular cylinder of the arm. It is distinguished very easily 
 throughout its entire extent by its deep colour, whilst the rest 
 of the hectocotyliform arm is wholly colourless. This colora- 
 tion is due to the chromatophora which beset the whole internal 
 surface of the sac, and may be seen shining through it. A semi- 
 lunar aperture, situated upon the dorsal face of the arm imme- 
 diately above the pedicle, leads into this sac, which is a true cul- 
 de-sac, and is closed upon all sides. We have never found any- 
 thing in this sac, which is obviously a diverticulum, an involu- 
 tion of the skin of the body itself, and whose formation depends, 
 as we shall soon see, upon the mode of development of the arm. 
 
 We have already many times mentioned the oval vesicle car- 
 ried upon a delicate pedicle, which was observed in many indi- 
 viduals in the place of the hectocotyliform arm. Upon closely 
 examining this vesicle, we see that it is lined in its whole extent 
 
AND THE MALES OF CERTAIN CEPHALOPODS. 147 
 
 with the same chromatophora as those which are distributed 
 over the whole surface of the body, and that it has at its base a 
 little semilunar aperture similar to that which we have observed 
 in the sac of the arm. Upon opening the vesicle we find in its 
 interior the hectocotyliform arm coiled up spirally (PL IV. fig.?), 
 so that its acetabula are turned towards the centre ; the dorsal 
 face of the arm towards the periphery of the vesicle. This arm 
 had reached its full development in the individuals in question ; 
 but in these also the vesicle had attained its final stage of deve- 
 lopment, since it is much smaller in a specimen described by 
 M . Verany in his work already quoted. Whilst we were examining 
 the arm rolled up in its vesicle, another living individual placed 
 in sea-water unrolled little by little the arm concealed within 
 its vesicle. The arm passed out by its base, and whilst it kept 
 on unrolling, the vesicle was reversed by the same action, and 
 ended by becoming the sac which we have described upon the 
 dorsal surface of the arm. It will now be readily explicable 
 why this sac has its internal face lined by chromatophora similar 
 to those of the skin, the external surface of the vesicle having 
 become the internal face of the sac. We can now also account 
 for the fact, that in all the individuals we observed the hectoco- 
 tyliform arm was always twisted and rolled up at its extremity, 
 an arrangement which was a result of the spiral coil which it 
 had formed in the vesicle. 
 
 We may be very concise in our description of the female or- 
 gans, which are constructed upon the same plan as in Argonauta 
 and Tremoctopus. The simple ovary surrounded by its capsule 
 is situate at the bottom of the intestinal sac, and communicates 
 with two very long and convoluted oviducts, which are folded 
 up upon the two sides of the ovary. There does not exist, as 
 in Tremoctopus violaceus, any decided glandular enlargement in 
 the course of the oviducts ; but in the sole female which we have 
 had an opportunity of examining, we found in the course of the 
 left oviduct two eggs of an oval form, which were still retained 
 in the oviduct, and which were evidently on their way out. The 
 two apertures of the oviducts are placed as in the two other 
 species of Octopods which have hectocotyline generation, (i.e. 
 Argonauta and Tremoctopusviolaceus,) at the base of the branchiae; 
 the oviducts passing under the branchial arteries and veins to 
 
 10* 
 
148 VERANY AND VOGT ON THE HECTOCOTYLI 
 
 open by two little lateral papillae into the respiratory cavity. 
 These apertures are very distant from the funnel, and are placed 
 altogether at the sides of the cavity. 
 
 The investigations which have been set forth in the preceding 
 pages ought, we think, to furnish a very complete solution of 
 this important question concerning the nature of the Hectocotyli 
 which has been agitated now for some years. Accepting the 
 results of MM. Siebold and Kolliker, and the conclusions which 
 they drew, one was still struck by a something surprising and 
 in strange contradiction with certain zoological principles which 
 were believed to be firmly established. Among these Cephalo- 
 pods so similar for the rest in their external and internal struc- 
 ture there were, according to this view, to be found kinds 
 which could hardly be distinguished generically, and yet in which 
 the difference between the organization of the male and that of 
 the female was carried to its greatest extent. According to this 
 view, females endowed with all the complicated and highly deve- 
 loped organs of the Cephalopoda possess males which previous 
 observers had taken for intestinal worms, and which in any case 
 were so poorly organized that independent life seemed refused to 
 them ; and so strange an exception, an example of which is 
 hardly to be found in the animal kingdom*, w r as to be found in 
 species side by side with others, in which the males were or- 
 ganized as completely as the females. It was evidently a ques- 
 tion which ought to be in the highest degree interesting to zoo- 
 logists, and we are rejoiced to believe that the solution we offer, 
 and which we believe to be definitive, will not remain without 
 influence in preventing for the future similar mistakes. 
 
 It would be useless to reiterate this truth, that the being dis- 
 covered by Laurillard at Nice, and described by Cuvier, is really 
 the detached arm of that species of Octopus which we call Trem- 
 octopus Carena, and that the individuals which carry these 
 deformed arms are always the males smaller it is true than the 
 females but for the rest organized in as complete a manner as 
 the other Cephalopoda. We have thought it superfluous to 
 
 * The Entovnostracous Crustacea, the Rotifer a, and the Cirripedia, classes 
 which present instances of disproportion between the sexes quite as remarkable 
 as Kolliker supposed it to be in Argonauta, &c., seem to have been forgotten 
 by MM. Verany and Vogt.-7y. 
 
AND THE MALES OF CERTAIN CEPHALOPODS. 149 
 
 give any detailed description of the nervous, alimentary, circu- 
 latory, and respiratory systems of these animals, the high organi- 
 zation of these systems being obvious from our figures or from 
 the mere inspection of the animal. It is the same for the male 
 of the Argonaut, although the difference in shape between this 
 and its female is still more remarkable ; so great indeed, that so 
 scrupulous an observer as our friend M. Krohn neglected to 
 examine these little creatures, which he took to be young just 
 hatched, and still provided with their yelk-sac. We have already 
 said that the discovery of these minute males of the Argonaut 
 belongs to Dr. Miiller of Wurzburg, who will without doubt 
 inform us that their internal organization resembles that of the 
 other Cephalopoda. We have only been able to examine a 
 single specimen of these minute males, long preserved in alcohol, 
 and given to one of us by M. Krohn, and we can affirm that in 
 point of external structure, which we have alone examined, it 
 perfectly agrees with the type of the other Cephalopods. This 
 is obvious from the figure we have given of this little male*. 
 The male of the Tremoctopus violaceus alone is not yet known ; 
 however, we have no fear but that further researches, in the di- 
 rection we have taken, will discover the male which bears the 
 Hectocotylus described by M. Kolliker, and which differs in many 
 points from the other Hectocotyli. 
 
 All the Hectocotyli that have been described up to the present 
 time as perfectly independent beings are then nothing else than 
 the detached arms of certain species of Cephalopods, in which 
 the males, for the rest perfectly normal, are smaller than the 
 females. All our observations prove that these arms are de- 
 tached with extreme readiness, and that the pedicle which 
 carries them exhibits, after its separation, a clean smooth surface, 
 without any trace of laceration. The detached Hectocotyli prove 
 as evidently that this separation takes place in a natural manner, 
 for their posterior extremity never exhibits any trace of tearing 
 nor of cicatrization. The pedicle which remains upon the 
 body after the arm has become detached, without question re- 
 produces this arm, and that probably by a process of budding, 
 comparable perhaps to the reproduction of the deciduous horns 
 of certain ruminants. Our observations have only permitted us 
 * Omitted here. 7V. 
 
150 VERANY AND VOGT ON THE HECTOCOTYLI 
 
 to make out the last phase of this reproduction, when the ab- 
 normal arm, coiled up in a spiral, is enclosed within a vesicle, 
 from which it ought soon to make its exit and unroll outwards. 
 But it seems to us unquestionable that the arm is really repro- 
 duced in the interior of this vesicle, by budding from the 
 peduncle and raising up the skin covering the latter, which thus 
 in the end forms the vesicle enclosing the arm. The vesicle 
 which the little male of the Argonaut carries has exactly the 
 same relations ; it also contains in its interior the spirally coiled 
 Hectocotylus. 
 
 Our observations as they stand could furnish only very scanty 
 indications as to the physiological function of these abnormal 
 arms of the males ; we have found in fact in these arms only 
 the ordinary structure of a cephalopod-arm terminated by the 
 flabellum a kind of tail fixed to one of the extremities, and 
 by a cutaneous sac at the other extremity. This sac was inva- 
 riably empty in the individuals in which the arm was still fixed 
 upon its pedicle; it is formed, as we have just seen, by the 
 retroversion of the sac in which the arm is developed. But our 
 investigations, combined with the results obtained by MM. 
 Cuvier, Laurillard, Kolliker, and Siebold, solve the problem. 
 All these observers have examined the Hectocotyli when de- 
 tached ; all have noticed that in these separated individuals the 
 sac situated at the base was by no means empty, but that it was 
 filled by organs belonging to the generative apparatus. MM. 
 Koliiker and Siebold have also determined that this sac contains 
 a long folded spermatic cord, which is continued into an ejacu- 
 latory canal, having a harder pointed extremity, which these 
 writers call the penis, inasmuch as they believe the full sac and 
 its contents to be a true testicle, with the excretory and copu- 
 latory canals, which are ordinarily in connexion with this organ. 
 Now, our observations are formally opposed to this interpre- 
 tation. We have proved in fact that the testicle is situated at 
 the bottom of the intestinal sac, and that it is constructed upon 
 the same type as that of other male Cephalopods. We have 
 shown besides, that this testicle is in relation with the peculiar 
 excretory organs which fashion the seminal mass, so as in the 
 end to form a seminal machine a spermatophore of a very 
 complicated structure and of very considerable dimensions. 
 
AND THE MALES OP CERTAIN CEPHALOPODS. 151 
 
 Now that we have exactly described the spermatophore con- 
 tained in the flask, let any one compare our description with 
 that which MM. Kolliker and Siebold have given of the contents 
 of the sac of the Hectocotylus, and the perfect agreement of the 
 two will be obvious : the spermatophore surrounded by a trans- 
 parent envelope, having the same properties as the envelope of 
 the supposed testicle in the Hectocotylus : the seminal cord of 
 the spermatophore resembling in all respects the same organ 
 rolled up in the genital capsule of the arm : the ejaculatory cord 
 of the seminal mass with its spiral ligament, its more solid and 
 pointed extremity, nowise different from the deferent canal and 
 the penis described by these authors ; there can no longer be 
 any doubt as to the identity of these organs. It is then evident 
 that the seminal machine constructed in the internal organs of 
 the male, leaves these organs to be transplanted into the sac 
 which the hectocotyliform arm carries ; this then, loaded, becomes 
 detached from its pedicle and affixes itself to the female, in all 
 probability during an act of copulation or embracing, which takes 
 place, as we know, among the other Cephalopoda. 
 
 It is true that no observation at present known explains to us 
 the mode of transport of the seminal machine from the aperture 
 of the generative organs situated in the branchial cavity as far 
 as the sac of the abnormal arm ; and it may be that the mobile 
 flabellum which terminates the Hectocotyll of the Argonaut and 
 those of our Tremoctopus Carena, is charged with the per- 
 formance of this removal of the seminal machine. M. Kolliker 
 has observed, in fact, that in one specimen of the HectQCotylus 
 Argonauta, the anterior extremity of the flabellum was bent back 
 into the aperture of the sac containing the seminal machine, and 
 that this extremity was twisted around the machine. It may 
 be that M. Kolliker surprised the Hectocotylus at the moment 
 when the flabellum was depositing its seminal mass in the sac of 
 the arm, though it is very possible on the other hand that this 
 engagement of the extremity of the flabellum was simply an 
 accident due to the continual explorations performed by the 
 organ. The acts of copulation and fecundation even are not yet 
 known to occur by direct observation 5 but as all the observers 
 who have up to this time found detached Hectocotyli have found 
 them on the arms, in the funnel, and in the respiratory cavity 
 
152 VERANY AND VOGT ON THE HECTOCOTYLI 
 
 of the females, it is probable that these charged arms creep by 
 the aid of their numerous suckers as far as the aperture of the 
 female generative organs, when the spermatophore then performs 
 its office. 
 
 We sum up then by offering the following conclusions : 
 
 1. The Argonaut, the Tremoctopus violaceus, and T. Carena, 
 have males whose structure agrees with that of the common 
 Cephalopod-type. 
 
 2. One of the arms of these males becomes specially modified 
 into a copulatory organ. 
 
 3. The beings known at present under the name of Hectocotyli 
 are not separate animals, but are merely the detached copulatory 
 arms of the males, charged with a seminal machine. 
 
 4. The copulatory arms are detached and renewed periodically. 
 
 DESCRIPTION OF THE PLATES. 
 
 [The great number of figures given by MM. Verany and Vogt rendered it 
 requisite to exercise some selection, and to exclude any that were not absolutely 
 necessary. Of their four Plates, the three last (PI. 7, 8, 9, Annales} are exactly 
 copied in our Plates II. III. and IV. ; but only two figures of their first Plate 
 (6, Annales} are given in our Plate I. figs. 3, 4. The others appeared to be 
 not necessary to the comprehension of the memoir. This change has of course 
 rendered requisite a new numbering of the figures.] 
 
 PLATE I. 
 
 Fig. 3. Tremoctopus Carena. Male, seen from the dorsal surface, a, aperture 
 of the retroverted sac which contained the Hectocotylus ; b, vesicle 
 which contained the flabellutn ; c, flabellum. 
 
 Fig. 4. Tremoctopus Carena (male), with the vesicle still containing its Hec- 
 tocotylus. 
 
 PLATE II. 
 
 Fig. 1. Male T. Carena, seen from the ventral surface. The visceral sac is 
 cleft longitudinally, and the left half of the mantle has been thrown 
 back to exhibit the branchia and the aperture of the male organs at 
 the moment of expulsion of the spermatophore. a, funnel ; b, vesicle 
 containing the Hectocotylus ; c, eye ; d, aquiferous aperture ; e, man- 
 tle; /, branchia; g, branchial heart; h, flask; i, spermatophore 
 passing out. 
 
 Fig. 2. The same. The mantle is cleft and thrown back, the funnel is taken 
 away ; the fibrous envelope of the abdominal cavity is cut so as to 
 
AND THE MALES OF CERTAIN CEPHALOPODS. 153 
 
 exhibit the organs in their natural position. The letters a h have 
 the same signification as before, i, abnormal arm, i. e. the Hectoco- 
 tylus ; k, the anus ; /, the rectum ; m, the large intestine ; n, the ink- 
 bag ; o, the ventral aorta ; p, the venous appendages. 
 
 Fig. 3. The genitalia with the branchiae, the hearts, and the large intestines, 
 wholly detached and seen from the ventral side. The letters as in 
 the foregoing figures, q, cornu ; r, testicle ; ^, aortic heart. 
 
 Fig. 4. The abdominal organs seen from the dorsal side, t, stomach ; u, caecum; 
 v, liver ; w, dorsal aorta. 
 
 * # * These four figures are twice the natural size. 
 
 Fig. 5. Abdominal organs of the female T. Carena, seen from the ventral side. 
 Natural size. The mantle is thrown back; the fibrous envelope of 
 the abdomen is taken away : for the rest the organs are in their na- 
 tural position, a, funnel; b, anus; c, branchiae; d, branchial hearts; 
 e, venous appendages ; /, sexual apertures ; g, ovary. 
 
 Fig. 6. The sexual organs isolated, seen upon the ventral surface and mag- 
 nified twice, a a, oviducts ; &, ovary ; c c, ova passing along the 
 oviduct. 
 
 PLATE III. 
 
 Figs. 1 4. The male sexual organs magnified 2 diam. completely detached 
 and viewed (figs. 1 & 3) from the ventral side, and (figs. 2 & 4) 
 from the dorsal side, a, flask with the aperture and the sperma- 
 tophore ; b, cornu ; c, testicle with the efferent canal. 
 
 Fig. 5. The cornu is open for its entire length. The deferent canal and the 
 accessory gland are unrolled, a, continuation of the cornu into the 
 neck of the flask ; 6, common reservoir ; c, aperture of the deferent 
 canal ; d, aperture of the excretory canal of the gland ; d', deferent 
 canal ; e e, clavate enlargements ; /, seminal mass contained in the 
 canal ; g, pyriform enlargement ; h, globular gland ; i, aperture of 
 the deferent canal ; k, envelope of the cornu ; I, excretory canal of 
 the accessory gland ; m, accessory gland ; n, efferent canal ; o, enve- 
 lope of the testicle ; p, testicle. 
 
 Fig. 6. Contents of the seminiferous tubes. X 400. 
 
 Fig. 7. Structure of the efferent canal. 
 
 Fig 8. Glandular sac of the accessory gland. X 400. a, capillaries. 
 
 Fig. 9. Seminal mass contained in the deferent canal. Posteriorly, only the 
 contour of the felted spermatozoa and the traces of the developing 
 transparent thread are indicated. , transparent thread. 
 
 PLATE IV. 
 
 Fig. 1 . Spermatophore withdrawn from the flask. 
 
 Fig. 2. Th6 anterior extremity of the same, considerably magnified and viewed 
 
 by transmitted light, a, transparent envelope ; b, ejaculatory cord ; 
 
 c, seminal cord. 
 Fig. 3. Posterior extremity of the ejaculatory cord in connexion with ihe 
 
 seminal cord, a, seminal cord ; b, fine membrane applying itself to 
 
154 VERANY AND VOGT ON THE HECTOCOTYLI. 
 
 the envelope of the spermatophore ; c, posterior extremity of the 
 ejaculatory cord ; d, commencement of the spiral membrane. 
 
 Fig. 4. A portion of the middle of the ejaculatory cord, o, tube of the cord 
 separated into two layers ; 6, spiral membrane. 
 
 Fig. 5. Anterior extremity of the spermatophore. 
 
 Fig. 6. Extremity of the acetabuliferons portion of the hectocotyliform arm, 
 with the commencement of the flabellum and the entrance of the sac. 
 a, flabellum ; b, muscular cylinder of the flabellum continued into the 
 arm ; c, nervous ganglia ; d, acetabula ; e, external layer of the sac ; 
 /, internal layer of the sac. 
 
 Fig. 7. The vesicle opened to show the abnormal arm coiled up in its interior. 
 X 2. 
 
 Fig. 8. Anterior extremity of the flabellum. #, muscular cylinder ; b, clavate 
 enlargement. 
 
 P'ig. 9. Part of the middle of the flabellum, considerably magnified, a, central 
 vessel ; b, parietes of the muscular tube ; c, skin enveloping the fla- 
 bellum ; d, lateral cutaneous muscles ; e, cutaneous vessels. 
 
 [T. H. H.] 
 
CRL'GER ox EPIGYNOUS MONOCOTYLEDONS. 155 
 
 ARTICLE VI. 
 
 Organographical Observations on certain Epigynous Monocoty- 
 ledons. By H. GROCER, of Trinidad. 
 
 [From the Linnaa, vol. xxii. 1849.] 
 
 1 HE development of the natural sciences from the time when 
 they first began to merit the name, may be divided into two 
 principal periods, according to the directions taken by research. 
 In the first, the object was the distinction of natural bodies from 
 each other, and the formation of what is called the systematic 
 part of science. After a body of facts had been brought to- 
 gether, inquirers, acquainted with distinctions, began to seek for 
 analogies, and thus more philosophical views respecting the 
 kingdoms of nature came gradually into existence. The Arti- 
 ficial Systems date from the first epoch, the Natural Methods 
 from the second. While the aim of systematic science is divi- 
 sion, that which searches for analogies endeavours to combine, 
 partly to facilitate the comprehension of the whole, partly in 
 order to discover the laws prescribed for the formation of bodies. 
 Both branches of science are immeasurable, and a lifetime is 
 insufficient for a tolerable mastering of only one of them. 
 
 One of the difficulties which especially oppose the acquire- 
 ment of an accurate knowledge of plants, is the circumstance 
 that certain parts of the globe possess peculiar forms which can 
 be obtained only at great cost and with much trouble in distant 
 zones. And here it is that descriptive botany has far outstripped 
 the branch to which this essay is devoted, although it cannot be 
 denied that much has already been done in this. Since I have 
 command here in Trinidad of abundance of material for the in- 
 vestigation of tropical plants, I may perhaps be permitted to 
 contribute the following, towards filling up a gap in special 
 botany. 
 
 The group of Monocotyledonea epigynae, comprising the Sci- 
 tamineae, Musaceae and Orchideae, is distinguished by certain 
 common characters from the other families of this division of 
 
156 CRUGER'S ORGANOGRAPHICAL OBSERVATIONS 
 
 the vegetable kingdom. Among these are the irregularities of 
 the parts of the flower, which have occupied the attention of 
 morphologists for some length of time. To these must be added 
 the high degree of development of the leaves, which in the Mu- 
 saceae and Scitamineae are separated from the petiole by a very 
 evident, swollen articulation, and which goes so far in most of 
 the Orchideae that the leaf becomes detached from its stalk at 
 this place. If, with Lindley, we exclude the Dictyogens as a 
 transitional class, this structure recurs in the Endogens only in 
 the Aroideae, in some of which the leaf falls off its stalk when 
 old, while others present real compound leaves, and in the 
 Grasses, which approach not a little to the Scitamineae in this 
 particular in such genera as Pharm, and in which the petiole 
 and lamina are most evidently distinct. These forms of leaf, it 
 may be remarked in passing, prove how mistaken those bota- 
 nists were who ascribed a folium petiolaneum to the Endogens 
 generally. 
 
 In most of the plants of the three families above named, with 
 which I am acquainted, it is seen at once that in those genera 
 in which the stem produces branches, the inflorescence is very 
 compound, and on the other hand, that where branches are only 
 produced on a subterraneous stem, the inflorescence likewise 
 remains pretty simple. To what extent this may be generalized 
 is a question I must leave to the decision of those who have 
 access to a large number of species, in collections, &c. In the 
 following pages will be found, where requisite, a short descrip- 
 tion of the parts of the flower of certain plants of these groups, 
 together with a fragmentary contribution to the history of their 
 development. 
 
 Musaceae. Heliconia Bihai, Sw. The accompanying diagram 
 (PL V. fig. 1) illustrates the relative position of the parts of 
 this flower. I must remark, that the generic character, as I find 
 it given by Endlicher and others, does not agree accurately with 
 the species of Heliconia with which I am acquainted here, and 
 we possess five in Trinidad. The two lateral, external, and the 
 three inner petals are more or less coherent, the outer petal next 
 the axis is free, and the stamen in front of this is abortive. 
 
 The inflorescence of this species is composed of a number of 
 abbreviated flowering branches which are attached to the rachis 
 
ON CERTAIN EPIGYNOUS MONOCOTYLEDONS. 157 
 
 alternately in two rows, enclosed in large bracts. The individual 
 flowers again stand in two rows, as shown in the diagram, upon 
 their almost horizontal support. It will be noticed that the 
 flowers do not stand in the middle behind the next bract, but 
 midway in front of another, and thus behind a third, which, 
 however, is separated from the flower itself by that lateral one. I 
 see only one way of explaining this strange arrangement of the 
 flower. The branch, like the rachis, represents a distichous 
 spike, with alternate flowers closely crowded, but is modified by 
 the two rows of flowers having approached near together late- 
 rally, at the side of the main axis, and the margin of each bract 
 having been interposed between the flower at its side and the 
 bract belonging to the latter. Under this supposition we must 
 assume the suppression of the bract belonging to the flower which 
 stands next to the axis. 
 
 The development of this flower takes place in the following 
 manner. The first sign of a bud, where it can be called inde- 
 pendent, is a perfectly simple, fleshy nodule, the second stage of 
 which is exhibited by its nearest, outer neighbour ; this second 
 bud, namely, already appears somewhat flattened at the top, and 
 almost as if a little depressed or excavated. After this we gra- 
 dually detect the parts of the flower, which however can only be 
 recognized by their position, since they present themselves as 
 very inconsiderable elevations. These parts are developed in 
 the order from without inwards, in which they subsequently lie 
 upon one another, but it is remarkable here that the stamen 
 which is ultimately to be abortive makes its appearance before 
 the rest, that is to say, at the same time as the inner petals, for 
 at one epoch of the development four parts may be distinctly 
 observed in the interior of the flower. The five other stamens 
 do not appear until afterwards. At this epoch and for a little 
 longer, the abortive stamen has twice or thrice the magnitude of 
 the rest. At the outset of the development, when the various 
 parts of the flower rise out of the formative mass, they are com- 
 pletely unconnected, and only begin to exhibit cohesion at the 
 lower part when the abortive stamen has already been left con- 
 siderably behind. I may observe, that it is unnecessary here to 
 assume that originally free organs subsequently become blended 
 together, in the true sense of the word ; for, since the points of all 
 
158 CRUGER'S ORGANOGRAPHICAL OBSERVATIONS 
 
 organs must present themselves first, while according to various 
 observations, organs cease to grow there soonest, and the points 
 of the petals remain permanently free, it may be supposed that 
 the lower parts of the flower are developed in a state of cohesion. 
 The development of stamens, where, as is well known, the anthers 
 are complete long before the filaments begin to show themselves, 
 offers another proof for this hypothesis. Since the two lateral 
 outer petals are adherent to the three inner below, while, how- 
 ever, they must be supposed to stand in an external circle with 
 the large, intermediate outer petal, and originate at the same 
 epoch of development, it is natural that the two lateral outer 
 petals should cohere only by the borders where they touch the 
 middle inner petal, with each other and with the latter, while 
 the borders which touch the large outer petal should remain 
 free ; which is really the case, since the border of this petal is 
 interposed between them above, of course, however, only to- 
 wards the apex of the flower, since all are uniformly coherent 
 below. 
 
 The only difference met with in the other species of Heliconia 
 we possess here, is, that the outer lateral petals remain free 
 somewhat lower down. In other respects all is as in //. Bihai. 
 The inflorescence of these other species is the same, only the 
 flowers are less crowded, and the outermost bract standing next 
 the rachis is abortive, which confirms the above explanation of 
 the inflorescence of the first-named species. 
 
 The following description of the flowers of Musa, as well as 
 the diagram (PL V. fig. 2), show that the Heliconite differ from 
 it not only in the inflorescence, but also in the place where the 
 sixth stamen is suppressed. This is not indicated in the syste- 
 matic works to which I have access. 
 
 Musa. 
 
 I have made out the following in the two species cultivated 
 here. The inflorescence is simpler than in Heliconia, i. e. be- 
 hind each bract (the apex of this bract sometimes grows. out 
 into a leaf) occur two transverse rows which are developed si- 
 multaneously and have no partial bracts. The three outer and 
 three inner petals are confluent below, and the third inner, the 
 back of which is towards the rachis, is free. The suppressed 
 
ON CERTAIN EP1GYNOUS MONOCOTYLEDONS. 159 
 
 stamen should stand here, and it makes its appearance in this 
 place very frequently in abnormal flowers. The female flowers 
 do not differ from the male in shape, except in the different 
 degree of development of the sexual organs. 
 
 The very young flower of Musa sapientum presents itself first 
 as a little flattened corpuscle, on which, shortly after its develop- 
 ment, the first trace of a division is exhibited on the side next 
 the axis, as a kind of furrow or rather a transparent line. A 
 little later this furrow becomes deeper, and a second appears on 
 the side next the bract, towards the top, the true apex of the 
 bud, which furrow runs all round the latter. From the part of 
 the flower lying outside this furrow are formed those five organs 
 of the flower subsequently coherent together, of which the inner 
 two petals do not become visible until after a certain interval ; 
 the inner free petal and the five stamens with the pistil are then 
 subsequently produced from the mass surrounded by the furrow. 
 By degrees the points are developed on the upper and outer 
 sides of the perigonial organs, as they appear in the full-grown 
 flower. From the central mass, as just stated, the stamens and 
 the inner perigonial leaf appear simultaneously and form one 
 circle. But the development of those stamens which stand be- 
 fore the outer petals advances much more rapidly for some time, 
 and even in the opened flower they are still somewhat larger 
 than the others. The pistil makes its appearance at a compa- 
 ratively late period, but I could only investigate this point in 
 what are called male flowers. 
 
 In Musa rosacea, which is cultivated in the botanic garden 
 here, the development of the perigonial organs takes place in a 
 somewhat different manner. The five segments of the flower 
 appear simultaneously, and are uniformly developed, so that 
 they cannot lie one upon another in the same way in the cohe- 
 rent flower. Moreover, the pistil here presents itself from the 
 first trifid, just as it appears in the full-grown flower, while in 
 Musa sapientum it originates simple and remains so. 
 
 Musa sapientum exhibits a multitude of interesting malforma- 
 tions, agreeing in this respect with most of the old cultivated 
 plants. The following includes those which I have had the op- 
 portunity of observing : 
 
160 
 
 A. In what are called female flowers. 
 
 1. With 6 stamens, very frequent, the additional 6th stamen 
 standing before the so-called labellum. 
 
 2. With 8 stamens, standing in one circle, the rest of the flower 
 normal. 
 
 3. With 6 stamens, one, two or three of which, standing before 
 the outer organs of the perigone, had assumed the form of the 
 labellum. 
 
 4. With 3 labella, 8 perigonial leaves confluent, one more 
 outside, standing behind the middle labellum, 11 stamens, 6 
 carpellary chambers (frucht-f acker), all these placed in circles 
 around a simple pistil. 
 
 5. The labellum confluent with the rest of the perigonial organs, 
 a free filiform body standing behind it. 6 stamens. 
 
 6. With 6 stamens, that standing behind the labellum bearing 
 an anther. 
 
 7- With 4 perigonial leaves, all blended together, 4 stamens, 2 
 carpels, one of the 4 petals opposite the bract, as also one of 
 the carpels. 
 
 B. In the male flowers. 
 
 1. With 6 stamens, all of normal form. 
 
 2. With 6 stamens, the 6th blended with the labellum below. 
 
 3. With 6 stamens, two of which, standing in front of the lateral, 
 outer petals, had expanded into the form of labella. 
 
 4. With 6 stamens and 3 labella. The two additional labella 
 standing, with a stamen, each in front of one of the outer 
 perigonial organs. 
 
 5. The two lateral outer perigonial organs free, the lateral inner 
 blended with the intermediate outer one. The rest of the 
 flower normal. 
 
 6. Tetramerous flower. With 2 labella in front, then 2 free 
 perigonial leaves right and left, and 4 others, blended together, 
 behind. 8 stamens, one of these adherent to the pistil be- 
 low, and one more added in the form of the labellum, stand- 
 ing in front of one of the lateral outer petals, 1 pistil and 4 
 carpels. 
 
 7- Twin flowers, very common, the perigone 3-parted, 2 seg- 
 ments in front simple, one behind 7-lobed, 5 labella, 12 sta- 
 
ON CERTAIN EPIGYNOUS MONOCOTYLEDONS. 161 
 
 mens, partly without anthers, arranged 6 and 6 round a 
 pistil. The middle labellum interposed with a fold between 
 the two circles of stamens, the rest of the perigonial organs 
 forming a circle. This twin flower is also common among the 
 female flowers. 
 
 It is seen that the commonest malformations are those in 
 which there are transitions from one condition into another, or 
 multiplications and confluences. Those, however, are more 
 important in which a dimerous or tetramerous flower is substi- 
 tuted for a trimerous. In these, if they have petals at all, the 
 labellum vanishes, and a stamen stands in front of each of those 
 remaining. The flower with eight petals appears to me, like the 
 twin-flower No. 7 B, a malformation originating through the 
 disappearance of the organs standing at the sides where the two 
 flowers are in contact. The labella standing side by side seem 
 to speak in favour of this. The first of these two tetramerous 
 flowers shows,, on the contrary, that the petal next the bract is 
 that which persists. The malformation A. 4. must be ex- 
 plained by a lateral doubling of the individual parts of the 
 flower, and then the middle labellum must be regarded as an 
 altered stamen. 
 
 Cannaceae. Calathea lutea, Spr. The flowers, as the accom- 
 panying diagram shows (PI. V. figs. 3, 4), are enclosed in pairs 
 in two bracts, of which the one standing on the side of the axis 
 represents the primordial leaf (vorblatt)* of a shoot; these 
 bracts, with their flowers, are again enclosed with two other 
 flowers in two older bracts, and the entire partial inflorescence 
 in a large dry involucral leaf (deck-blatt). Each individual 
 flower possesses a small involucral leaf (deck-blatt} standing at 
 its side, as looked at from the axis or from the side where the 
 general involucral bract occurs. This arrangement of the flowers 
 has the greatest analogy to that of the branches, except that in 
 the latter only one branch occurs between a leaf and a primor- 
 dial leaf (vorblatt) 9 instead of two flowers. The unfolding of the 
 
 * The term "primordial leaf" (Bravais) or "vorblatt" (Schimper) is ap- 
 plied to the first leaf or pair of leaves of a shoot, which exhibit peculiarities ; in 
 many cases, they are regarded as representing on the shoot, the cotyledonary 
 leaves of the primary stem. 
 
 SCIEN. MEN. Nat. Hist. VOL. I. PART II. 11 
 
162 CRUGER'S ORGANOGRAPHTCAL OBSERVATIONS 
 
 shoots, like that of the flowers, begins at the stem side and ad- 
 vances towards the oldest leaf. With regard to the arrangement 
 of the parts of the flower, it is sufficient to remark that one of 
 the sepals stands outside, i.e. neither next the main axis nor 
 the leaf, and consequently two stand where, if there were branches 
 here instead of flowers, the axis of the branch must stand. The 
 anther stands between these two last sepals, and on the outside of 
 that one of these which stands beside the main axis, is observed 
 the bract above mentioned. In this species, as well as in others 
 with analogous inflorescence, the true bract, belonging to each 
 branch, is suppressed in the youngest flowers, and indeed sup- 
 pression of involucral bracts (deck-blattern) appears to be a fre- 
 quent occurrence in this family generally. The primordial leaf 
 (yorblatf), however, is always present. Since there can be no 
 mistake about the import of the latter, as its position testifies to 
 its analogy with this organ in many other Endogens, this inflo- 
 rescence may be regarded as a series of successive branches 
 apparently arising from the same point. The two flowers 
 standing side by side are moreover to be regarded as two other 
 branches which also arise from the same point, but whose un- 
 folding at different times proves that they must have originally 
 stood alternately upon their branch. The bract of each flower 
 is suppressed, the little lateral bract appears to belong again to 
 another absent flower, and demonstrates the branch-nature of 
 the flower. The arrangement of the flower may therefore be 
 explained here as distichously alternate, just as occurs fre- 
 quently in nearly allied genera, such as Thalia and Maranta. 
 
 The young flower-bud first appears here as a simple gela- 
 tinous nodule, which likewise becomes somewhat excavated on 
 its upper surface before the separate parts show themselves di- 
 stinctly. The outer parts of the flower next become evident, and 
 then the second circle, which some authors call the outer circle 
 of the corolla. Not until both are perfectly evident, and have 
 even assumed the leafy or scale-like form, do we see the parts 
 surrounding the style appear, which they do simultaneously, 
 although the anther is noticed almost first, since it is found even 
 from nearly the beginning considerably larger than the rest of 
 the internal floral organs. The anther stands in front of one of 
 
ON CERTAIN EPIGYNOUS MONOCOTYLEDONS. 163 
 
 the inner segments of the perigone, a little to the side, since only 
 one of its cells is destined to be perfected ; opposite to it stands 
 the labellum, the development of which, in the very early con- 
 ditions, outstrips the two lateral innermost parts of the flower. 
 After this all remain very backward in their development, and 
 only attain their large size in comparison with the anther, at a 
 later epoch. With regard to the anther itself, it appears first 
 as a little globule or vesicle, and a furrow is gradually formed 
 on its anterior side. It deserves mention, that before the twist- 
 ing and lateral development of the parts, the tooth which occurs 
 on one side of the full-grown labellum is the oldest part of this 
 organ, and stands in the middle of the young flower before the 
 anther. The stigma comes to light last, as a little body exca- 
 vated on its upper surface, and it rises up with the other organs 
 of the flower. I must here again declare against any fusion of 
 originally distinct organs ; the lower parts of the floral organs do 
 not begin to elongate until a later period, and are confluent from 
 the first. 
 
 Two species of Canna which I have been able to observe in a 
 young stage, exhibit exactly the same conditions. The peta- 
 loid filament only acquires at a late period the expansion which 
 it exhibits in the full-grown condition, and the same is the case 
 with the rest of the inmost organs, which in the earliest condi- 
 tion appear as little globules, just like the anther. The inflo- 
 rescence here again agrees with the mode of ramification of the 
 plant ; the flower-branches describe a three-membered spiral 
 round the stem ; from each member of this spiral arise 2 to 3 
 flowers, or only 1 or 2 flowers occur with 2 to 3 bracts. The 
 primordial leaf (vorblatt) we see occupy so important a place 
 in Calathea, is here regularly suppressed in the little partial 
 branches, which indicates that each 2-3 flowers correspond to a 
 single flower, if we regard each single lateral bract of the latter 
 as belonging to another flower. 
 
 With regard to the import of the parts of the flower of this 
 family, the view of Lestiboudois and Lindley, according to which 
 the more or less foliaceous organs situated inside the outer two 
 circles of the flower are stamens, appears to me the most correct, 
 when we take into account the history of the development. The 
 outer two circles of the flower are quite developed at the time the 
 
 11* 
 
164 CRUGER'S ORGANOGRAPHICAL OBSERVATIONS 
 
 other organs make their appearance, and the latter all show 
 themselves at once, as in the Musaceae. 
 
 The symmetrical arrangement of the parts of a natural object, 
 and of a plant in particular, is so general a law, striking even 
 the uninstructed, that a deviation from it must be considered as 
 a most extraordinary phenomenon. So far as I know, the 
 flower of the Cannaceae is almost the only one that can be re- 
 garded as asymmetrical. A glance at the diagram (PI. V. fig. 5) 
 is sufficient to prove that this flower may be regarded as per- 
 fectly symmetrical, if we assume to exist, in the midst of the two 
 or three flowers which are found together, an axis around which 
 the flowers are arranged in a more or less simple spiral. In this 
 case the anther stands on the side of the hypothetical axis, just 
 as in the Zingiberaceae, and then consequently no distinction 
 can actually exist between these two families. The great irre- 
 gularity which we observe in the full-grown flowers arises sub- 
 sequently through twisting and lateral development. 
 
 Zingiberaceae. Costus spicatus, Sw. While the flower of the 
 Cannaceae is difficult to define at first sight, that of the present 
 beautiful family will be found very easy to understand. Yet 
 after all, as I have endeavoured to show above, it is only the 
 inflorescence which causes these difficulties. Among the proofs 
 of this is the circumstance that the same difficulties occur in 
 the Zingiberaceae, if the inflorescence is not properly inter- 
 preted ; only the matter is simpler here from the flowers being 
 regular. 
 
 A glance at the diagram of Costus (PI. V. fig. 6) will give an 
 idea of the mode of arrangement of this flower and its rela- 
 tion to the axis and bract. Here the labellum is assumed to be 
 a simple element, but in many Zingiberaceae, as is well known, 
 two little leaflets occur at its sides, which are more or less con- 
 nected with it. The labellum of this species is three-lobed at 
 the apex with very inconsiderable indentations ; there is an addi- 
 tional smaller lobe at each side. The leaves of the species of 
 Costus are, as is well known, arranged in very distinct spirals, 
 and there also exists a twisting of the axis. The spiral of the 
 leaves is much contracted in the spike ; behind each bract stands 
 a solitary flower with a small lateral involucral bract (deck-blatt), 
 which stands in front of the flower in the direction of the prin- 
 
ON CERTAIN EPIGYNOUS MONOCOTYLEDONS. 165 
 
 cipal spiral. This small bract may be regarded, as in the Can- 
 naceae, as belonging to another suppressed flower, and it is con- 
 sequently analogous to the two little bracts which we find at 
 the base of the flowers in so many Dicotyledons. This frequent 
 supposition of flowers without bracts, and involucral bracts (deck- 
 bl'dtterri) without flowers, would not be justifiable, were not such 
 conditions more clearly exhibited, for example, in Alpinia nutans 
 or racemosa. Moreover, we continually meet with one or other 
 in the Cyperaceae, Grasses, Bromeliaceae, and many other 
 plants. 
 
 The mode of composition of the spikes of a Costus is un- 
 usually favourable to organogenetic investigation. If we select a 
 spike not too old, we may trace all the stages from the dehiscent 
 fruit to the bud forming merely a milky papilla behind its 
 bract. In this young condition I never could detect a bract at 
 the side of the bud, but it was distinctly visible by the time the 
 bud approached the form of a nodule. This nodule then began 
 to exhibit an excavation in its upper surface and towards the 
 large bract. Next, in the middle of this excavation appeared 
 another papilla which also soon became concave ; the sepals then 
 began to separate distinctly, at least the two standing on the 
 side next the axis. The cavity formed by the second circle of 
 organs is at first of longish-round, but soon passes into a trian- 
 gular shape. Thereupon three symmetrically arranged furrows 
 show themselves between this excavation and the outer border of 
 this circle, one behind each of the sides of the triangular excava- 
 tion, while a little depression is observed at the place where the 
 middle lobe of the labellum is to appear. The said furrows quickly 
 run together and coalesce, so that soon afterwards the anther 
 and the labellum with its three lobes are distinctly indicated. 
 The two additional segments of the sides of the labellum make 
 their appearance somewhat later, when the labellum, which for 
 a short time forms with the anther a circular ridge in the inte- 
 rior of the flower, interrupted only by the middle lobe, separates 
 and proceeds independently in its development. If we open a 
 rather older flower, we find all five lobes of the labellum already 
 developed, and the furrows of the anther also becoming evident. 
 
 The stigma deserves especial attention. It is first observed 
 at the bottom of the flower, as a little, somewhat flattened ele- 
 
166 CRUGER'S ORGANOGRAPHICAL, OBSERVATIONS 
 
 vation, which begins very early to be somewhat emarginated 
 above. When a little older this upper surface assumes the form 
 of a disk inclined greatly towards the bract, exhibiting in front 
 two distinct teeth, with a furrow below them. By degrees, that 
 part of the stigma where the furrow is, begins to run up, more 
 like the other side. In the full-grown condition, the teeth, 
 which originally occupied the summit of the style, are found as 
 a pair of little papillae on its back, and the said furrow becomes 
 the real stigma, in which are ultimately found the capillary 
 cells between which the pollen-tubes make their way into the 
 ovary. 
 
 The most interesting fact in the history of development 
 just given, appears to me to be the formation of the anther 
 and labellum in this flower. The anther and labellum, as we 
 have seen, do not extricate themselves from a mass remain- 
 ing in the centre of the flower, as in the other flowers observed, 
 but a number of furrows, corresponding to the arrangement of 
 the inmost circle, are formed in the inner side of a circle of 
 organs already developed ; not divided, it is true, but suffi- 
 ciently characterized by form and position. A little later we see 
 the anther and labellum forming one connected body, and the 
 lobes of the latter then become apparent in this. Here there- 
 fore we might assume the production of a circle of organs by the 
 radical deduplication of the corolline organs, which would be 
 borne out by the development. But leaving out of the ques- 
 tion that in Calathea, for instance, where the necessity of such 
 a circle of organs exists quite as much, there is not a similar 
 mode of development, it might equally be supposed here, that 
 the two circles were originally confluent into one mass. And it 
 may be urged against the first hypothesis, that at the time when 
 the anther and labellum are still connected, the lobes of the latter 
 are already indicated, at all events three of them, the middle one 
 of which, alternating with the corolla, is unfavourable to this 
 theory. But this early division of the labellum (so contrary to 
 what is observed in other foliaceous organs) is that which, in 
 my opinion, may on the other hand be brought to support the 
 assumption that the original organs lying between the six outer 
 organs of the flower and the pistil are to be regarded as stamens. 
 Thus the course of development here is as favourable as possible 
 
ON CERTAIN EPIGYNOUS MONOCOTYLEDONS. 16? 
 
 to certain speculations. To me it only tells for the present that 
 nature here also displays the greatest variety, or that we are 
 still ignorant of the laws which she follows here. 
 
 Orchideae. Epidendrum bicornutum, Hook. The inflores- 
 cence of the Orchidese (PL V. fig. 7) is in general, as every one 
 knows, very simple, and offers no difficulties. The curvature 
 of the peduncle, so frequently observed, produces great varia- 
 tions in the external appearance of this lovely family, but it is of 
 very slight or of no value for generic characters, although this 
 particular is included in them by some. 
 
 In the above-named plant, very common here on rocky sea- 
 shores, the bud first shows itself behind the bract as a roundish 
 slightly flattened nodule, which is soon converted into a little 
 cup with an undivided border, at the bottom of which the traces 
 of the rest of the parts of the flower are seen at that time as a 
 still undivided mass. Shortly afterwards, the outermost organs 
 of the flower become distinct by the border of the cup growing 
 considerably at the places corresponding to these, while no 
 development occurs at the points corresponding to the fissures 
 separating them. Then three little papillae make their appear- 
 ance in the middle of this flower, and directly afterwards the 
 fourth organ, the anther, which is so situated between the lateral 
 inner petals, that it forms a circle with them and the labellum. 
 All these organs then increase in breadth, and the anther soon 
 exhibits a furrow in front. The parts of the stigma appear 
 later, at first only just indicated by a little swelling at the point 
 of attachment of the anther. But by degrees the column rises 
 out from the body of the flower, and the anther, which at first 
 is quite erect, bends down upon it after its cells are perfectly 
 developed. '- The labellum merits especial attention. Up to a 
 comparatively late epoch this has so much the form of the 
 anther, that the latter can only be distinguished from it by its 
 greater thickness and its position. At a rather later epoch 
 the anther is found still obtuse at its apex, while the labellum is 
 apiculated, and at a somewhat more advanced period the labellum 
 exhibits the processes, first the lateral notches on the border, and 
 in particular, still later, the two calli, so strongly marked in the 
 perfect flower, to which the plant owes its specific name. 
 
 Such is the course in the flower of an Epidendrum with the 
 
168 CRUGER'S ORGANOGRAPHICAL OBSERVATIONS 
 
 labellum almost free, for comparison with which I have traced the 
 development in another species where the labellum is adherent 
 to the column as far up as the anther. This is an Epidendrwn with 
 almost equal sepals, the inner of which merely is a little broader, 
 and a labellum with four calli on its expanded limb, which is 
 three-lobed, the lobes being most elegantly fringed. The column 
 with the labellum is, in the full-grown flower, about twice as 
 long as the remaining organs of the flower. Here the young 
 bud makes its first appearance exactly as in the above-described 
 species, and as in the other plants spoken of, and very soon 
 passes into the form of a cup, larger in the direction of its 
 breadth. Inside this is first distinctly seen the labellum, and 
 immediately afterwards the other three inner organs of the 
 flower, in a row in front of the labellum. The rest of the 
 development resembles that of the above-named flower, with the 
 distinction that the foot of the column with the confluent la- 
 bellum becomes elongated at a much later period. I have not 
 been able to observe any fusion of the two organs ; there is 
 nothing blended in the full-grown flower which was not con- 
 fluent at the time of its first appearance. The considerable 
 elongation of the lower portion of the floral organs presenting 
 itself only at a late period, may be observed, among other 
 instances, in the sexual organs of Cleome and the Passifloreae ; 
 all this must lead me to declare against a subsequent fusion of 
 originally separate organs. In this Epidendrum also, the lateral 
 lobes of the labellum, as well as the calli upon the surface of 
 the limb, appear late. With regard to the column, it must be 
 observed that the anther is not so broad in the full-grown condi- 
 tion as the organ upon which it rests, while in the young state 
 it is fully three times as broad as the latter, which circumstance 
 again indicates that mode of development of which I have spoken 
 above. 
 
 In this Epidendrum, as perhaps in all Epidendra, the anther 
 is found erect at a comparatively late epoch ; in some Vandea 
 I have observed this lying at the bottom of the flower at an 
 early epoch. In Oncidium ampliatum, Lindley, I have seen the 
 anther existing as a little papilla lying in the midst of the inner 
 petals at the epoch when they first begin to expand laterally. 
 
 On the whole, the above observations of development have not 
 
ON CERTAIN EPIGYNOUS MONOCOTYLEDONS. 169 
 
 yielded me any result which can serve as evidence in interpreting 
 the nature of the labellum and the column. The segments of 
 the perianth generally present themselves just as they appear 
 in the full-grown flo \vers, with a few exceptions which are 
 readily explicable, and do not differ from known modes of deve- 
 lopment of foliaceous organs. That what is called an epigynous 
 flower first presents itself as a simple body, as observed in all 
 these plants, will not be found strange when we recollect that 
 the same has long been established in gamopetalous flowers, 
 and that in the majority of cases there is no essential distinction 
 between flowers of the two kinds, except the radial confluence. 
 I may add that I am not in a position to cavil at or to under- 
 value observations and opinions which have emanated in part 
 from distinguished philosophers ; on the contrary, those theories 
 are so much the more worthy of admiration, since in some cases 
 they were necessarily set up without knowledge of the history 
 of development. Rightly and by universal agreement have the 
 physical sciences been ruled since the middle of the last century 
 by direct experience, but far too much power would be claimed 
 for this, if we condemned everything which had not yet been 
 confirmed by it. 
 
 If now, in reviewing these four families, we direct our at- 
 tention to the mode of arrangement, we are in the first place 
 struck by the fact that the calyx and the corolla stand in an 
 unchangeable relation to the bract and to the axis* Lindley 
 appears to wish to make the Orchideae an exception to this, 
 ascribing to this family an additional outer circle of floral 
 envelopes, occurring in Epistephium, of which organs one must 
 therefore fall next the axis and two towards the bract. And he 
 uses this as a support for his opinion of the morphological com- 
 position of the flower of the Orchidere, to which we shall return 
 in the sequel. Disregarding the objection that so rare a case as 
 the appearance of a calyculus, even if it should occur in certain 
 other genera, would scarcely prove anything for the entire 
 family, unless it were accompanied by other conditions, and 
 further, that this calyculus has not yet been investigated in its 
 earliest conditions, &c., such a mode of arrangement is a very 
 
170 CRUGER'S ORGANOGRAPHICAL OBSERVATIONS 
 
 extraordinary event among the Endogenae and deserves little 
 trust*. And it ought also to be noted, that in the flowers of 
 Musa above described, when 3 6-parted flowers passed into 
 2- or 4-parted, the leaf next the bract retained its relative po- 
 sition. This circumstance also appears to answer the question 
 whether the arrangement of the parts of the flower is determined 
 by the bract or by the axis, in so far that the former keeps fixed 
 the organ standing next above itf. On the other hand, to con- 
 
 * Through a lucky accident I have been able to settle this matter. In our 
 lower savannahs is found a very elegant species of Epistephium, which I was 
 enabled to obtain in all stages of development, at the moment when I intended 
 to send off the above little essay. In this species the calyculus possesses three 
 largish teeth standing behind the outer segments of the perianth, a small one 
 under the labellnm and a pair of indistinct little teeth, one on each side of the 
 larger tooth next the bract. The rest of the arrangement agrees exactly with 
 that in other Orchideae : of other characters I have seen that the outer seg- 
 ments of the perianth never wholly cover the two lateral inner ones, but a 
 thick midrib remains exposed in each of the latter. The seeds, moreover, have 
 an appearance which seems to me unusual among the Orchideae ; the testa, 
 namely, is expanded into a wing running round the nucleus. The develop- 
 ment of the segments of the perianth is in agreement with the mode in which 
 they subsequently overlie one another. At each side of the little nodule which 
 is the first representative of the flower of this plant, we observe a little point, 
 the first trace of the sepals, and a little later the middle sepal ; at the same time 
 with the latter, the two lateral inner segments of the perianth. Then the 
 labellum appears, and almost simultaneously with that the anther. In this 
 flower also the anther is at first erect, although it subsequently lies upon the 
 summit of the column. Up to this time no trace of a calyculus is to be seen ; 
 it first presents itself clearly when the flower rises above the axil of the bract 
 and the boundary between the ovary and the segments of the perianth becomes 
 visible. The calyculus is persistent upon the fruit, while the other parts 
 separate from it at a very early period. 1 believe I am justified in concluding 
 from the foregoing, that the calyculus, when it presents itself in the Orchideae, 
 does not represent an external circle of organs, because (1) its segments do not 
 alternate with those of that standing above it ; (2) they originate later than 
 those ; and (3) because they persist upon the capsule, while the other parts 
 become detached. I should lay much stress upon the last reason, yet I think 
 that this calyculus must be regarded as analogous to that which may be 
 observed on the fruits of certain Compositae, Dipsaceae, &c. 
 
 f In the Dicotyledons also it may frequently be observed, that the sepal 
 which lies outside keeps its place in malformations or changes of numeral 
 relation. Thus in the Myrtaceae, Melastomaceae and Onagraceae (Jussieua). 
 Several species of the last vary uncommonly in their numerical relations ; one 
 segment of the calyx always lies next the bract. The same occurs in Osbeckia 
 glomerata when it presents ternary circles of organs, as sometimes though 
 rarely occurs. How far the assumption of the position of the floral organ lying 
 
ON CERTAIN EPIGYNOUS MONOCOTYLEDONS. 
 
 sider the matter on all sides, the view which assumes the exist- 
 ence of an outer circle of organs, gives the flower of the Orchideae 
 a greater analogy with the Scitamineae in reference to the relative 
 position of the anther. Those also who regard the anther of 
 the Cannaceae as standing in front of a lateral inner petal, must 
 make an exception to the rule that one of the three sepals falls 
 next the bract standing nearest to the flower. But as it is a more 
 logical proceeding to regard the side of the flower where the 
 anther occurs as the real axial side, that rule may be assumed 
 as valid here, whether that bract is present or not. 
 
 In addition to the ample number of characters which distin- 
 guish the Orchideae from the Scitamineae, the position of the 
 anther, as above indicated and universally recognized, exhibits 
 an important difference. While in the latter it stands at the 
 axial side of the flower and embraces the style, or in certain 
 Cannaceae is only blended with the latter through the medium 
 of the tube of the perianth, in the Orchideae it stands to a 
 certain extent upon the style and on the bracteal side. In the 
 Musaceae both variations of the arrangement occur simulta- 
 neously. In Heliconia, as above mentioned, the five stamens 
 stand on the axial side of the branch upon which the flowers 
 occur ; in Musa, on the side next the bract ; in Heliconia, more- 
 over, the abortive stamen stands in front of the middle outer 
 segment of the perianth. With this is combined a remarkable 
 variation of the inflorescence, which I have already indicated 
 above. The flowers of Musa standing sometimes in one, some- 
 times in two transverse rows, are all of one period of development, 
 while in Heliconia they are developed in succession, in the order 
 in which they approach toward the bract. 
 
 The ordinary view is, that the six stamens of Monocotyle- 
 dons belong to two successive circles. Although this is very 
 clear in theory, no proof for the assertion can be found in the 
 course of development of the flowers here under examination. 
 In most cases I have distinctly seen the two outer circles of 
 organs arise in succession, but in Musa and Heliconia I have 
 
 next the axis being changeable, is applicable to the vegetable kingdom in ge- 
 neral, I must leave to be discussed by others. In the place where I live, I 
 must necessarily always be some years behindhand in literature, and thus it 
 seems to me that this question has not met with all the attention it deserves. 
 
1?2 CRUGER'S ORGANOGRAPHICAL OBSERVATIONS 
 
 just as distinctly seen all the stamens appear simultaneously. I 
 have observed the same in the innermost circle of appendicular 
 organs in the Scitamineae, which in Costus, for example, appear 
 clearly all at once*. In Mma rosacea, it will be recollected, 
 even the segments of the perianth all originate at one time, so 
 that they do not always overlie one another in the same way. 
 In like manner we have seen the labellum of Musa sapientum 
 originate with the stamens, but it would scarcely occur to any one 
 to explain it as a metamorphosed stamen on this ground, since 
 it is too strongly characterized by position and form, and by the 
 fact that a stamen often stands before it in monstrous flowers. 
 On the other hand, it cannot be denied that the said circum- 
 stance referring to the period of its development, andjthe frequent 
 transformation of stamens into labelloid bodies, indicates a kind 
 of transition from one to the other. 
 
 Few flowers indeed have been the subject of so many theories 
 as the Orchideae. Without enlarging upon the literature of this 
 point, I must yet observe that Lindley, in his ( Vegetable King- 
 dom/ retains his older view on this subject, and only indicates 
 an alteration on one point. While assuming, as above men- 
 tioned, an additional circle of organs on the outside, he calls the 
 inner organs, immediately surrounding the column, metamor- 
 phosed stamens, and presumes that the stamens contained in 
 
 * In the not very distantly related Bromeliaceae I have observed the same 
 in Billbergia, although a portion of the stamens is blended with the inner seg- 
 ments of the perianth in the full-grown flower. Another condition allows of 
 the conclusion of a simultaneous origin of the stamens in this flower. As is 
 well known, the organs are all more or less twisted, and in such a manner that 
 the petals exhibit an opposite direction to the sepals, and so on ; the lobes of 
 the stigma have the direction of the second circle. Now if the stamens origi- 
 nated at two successive epochs, the lobes of the stigma ought to exhibit the 
 same direction as the sepals. The different direction of succeeding circles in 
 twisted flowers, very evident sometimes in the calyx and corolla of the Mela- 
 stomaceae also (in the Apocyneae where, as is well known, the segments of the 
 calyx stand in the quincunx, the direction of the corolla is opposite to the 
 spiral described by the sepals), is certainly most favourable to the movement of 
 the organs in the interior of the flower during their growth. It must be 
 remembered also that this direction, different when seen from outside, is the 
 same where two circles touch, and that if the opposite condition occurred, the 
 organs must be interposed between each other. How far that consideration 
 can be used as a criterion, as I have ventured to use it in the Bromeliaceae, I 
 must leave for the decision of the masters of science. 
 
ON CERTAIN EPIGYNOUS MONOCOTYLEDONS. 
 
 the column are the inner circle of these. And then he gives 
 up his earlier opinion as to the stigma of the Orchideae, and 
 assumes that its arms are opposite to the lateral organs of the 
 outer circle of the perianthial organs. 
 
 With regard to the first point, I have already advanced some 
 arguments against the assumption of a calyculus as typical, 
 and cannot but think Endlicher's view, as laid down in his 
 ( Genera Plantarum/ the more correct, chiefly because the soli- 
 tary anther in every case stands in front of that outer organ of 
 the perianth, which falls next the bract. The complicated nature 
 of the labellum appears to me to be shown both by its so fre- 
 quent confluence with the column, and by the cases where all 
 the other organs of the perianth are blended together, and the 
 column alone remains free. The history of development is quite 
 silent on this point, as well as in reference to the column, at 
 least in the above plants. But I have no doubt that the Neottieae 
 display the composition of the column most distinctly in their 
 development, just as, moreover, the analogy of the Orchideae with 
 the Scitamineae is rendered most clear by this group. In a series 
 of monstrosities of Ornithocephalus in my possession, there is 
 one which has only one simple filiform body at the bottom of 
 the flower, and another where two such organs are observed one 
 standing behind the other, evidently anther and column, arrested 
 at the lowest stage of development*. 
 
 In reference to the explanation of the stigma of the Orchideas, 
 
 * Since monstrosities in general, so interesting in many respects, do not 
 always prove much in other directions, I cannot accord very great value to the 
 various monstrosities observed in the Orchideas. When three anthers occur 
 instead of one upon a column, the additional two may just as well be called a 
 monstrous multiplication of the central one, as a retrogression to the tvpe ; even 
 as, for example, a pelorian Linaria by no means proves that the flower of Linaria 
 ought to have five spurs. On this ground pelorice in general ought to be divided 
 into two groups, one comprehending those where the regularity is restored by 
 the multiplication of an existing irregularity. To return to the Orchidese, I 
 have observed blossoms of Isochilus where in almost every case three anthers 
 occurred instead of one ; and where in one case I found only one, there were 
 still two empty ones by its sides. But this is certainly not a further return to 
 the type. If however, on the whole, no doubt can exist now-a-days as to the 
 morphological import of the column, it must still be observed, that no mon- 
 strosity can demonstrate how it should properly appear, and that if ever a co- 
 lumn should present itself separated into its elements, this might have a totally 
 different character. 
 
174 CRUGER'S ORGANOGRAPHICAL OBSERVATIONS 
 
 it seems to me as though the development and character of this 
 organ might throw some light over this subject, although analo- 
 gies, often only apparent, cannot wholly decide such a question. 
 When, for instance, in agreement with their mode of development 
 and their arrangement, we regard the two calli which occur under 
 the stigma as the points of two carpels, the tube which leads to 
 the germen is formed only on the outer carpel, and indeed, as it 
 seems, on the back of it. It may be equally assumed in the 
 Orchideae, that the canal of the stigma is developed in that 
 carpel falling next the bract, while the other two, lying next the 
 labellum, may be supposed to be buried in this, which at the 
 same time gives a kind of explanation of the frequent resem- 
 blance between the labellum and the column. Of course the 
 many arms and branches of the latter remain unexplained here, 
 unless we consider that this is itself a complex organ. The 
 mode of dehiscence of the capsule of the Orchideae favours the 
 view which assumes six instead of three carpels in this family, 
 and the loculicidal dehiscence is likewise analogous to that most 
 frequent in the groups nearest allied to the Orchideae. It is 
 worthy of observation in the Bromeliaceae, that in the genera 
 which have a dry fruit, sometimes the loculicidal, sometimes the 
 septicidal dehiscence occurs, according as the fruit is blended 
 with the circles of organs surrounding it, or is possessed of a free 
 superior ovary. Among the Orchideae, the fruits of Cryptar- 
 rhcena lanata, R. Br. ; Dichcsa graminoides, Lindl. ; and certain 
 species of Pleurothallis, open on one side, i. e. two valves 
 standing at the side of the column remain connected together, 
 and the third, which stands below the labellum, separates from 
 the others by two fissures. The ribs, which in other species 
 separate from the placentiferous valves, are entirely wanting 
 here. It would seem as if the firmer combination of the valves 
 below the column, in these cases, was produced by the stamen 
 occurring above them. But it must not be forgotten that in all 
 these cases the septa, or in one-celled fruits the placentas, alter- 
 nate with the sepals. 
 
 The mode, however, in which a fruit bursts, cannot prove any- 
 thing concerning its morphological nature. The great variation 
 which prevails in this phaenomenon, the circumstance that 
 otherwise very nearly allied genera exhibit essential differences 
 
ON CERTAIN EPIGYNOUS MONOCOTYLEDONS. 
 
 in this particular, testify that no great stress can be laid upon 
 this part of vegetable life, in regard to the import of organs. In 
 this case, as in all others, an earnest study of the arrangement 
 of the organs will, sooner or later, probably solve the question. 
 
 DESCRIPTION OF PLATE V. 
 
 Fig. 1. Diagram of Heliconia. B, Universal bract; b, partial bracts, the 
 figures show the flowers to which these belong. Ax, main axis; ax, 
 axis of the branch. The noughts (0) indicate in this, as in the suc- 
 ceeding diagrams, the places where stamens are abortive ; the points 
 () actually existing stamens or anthers. Where a nought is crossed 
 through (0), it indicates a petal taking the place of a stamen. 
 
 Fig. 2. Diagram of Musa. 
 
 Fig. 3. Diagram of Calathea, showing how the flowers are enclosed in a 
 bract and a floral leaf (yorblatt) ; bb, little bracts. 
 
 Fig. 4. Diagram of a single flower of Calathea. 
 
 Fig. 5. Diagram of Canna. IB, 2s, 3s, large bracts; b and c, small bracts. 
 
 Fig. 6. Diagram of Costus. B, large bract; b, lateral, small bracteal leaf 
 (deck-blati). 
 
 Fig. 7. Diagram of Orchidea. 
 
 [A. H.] 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 ARTICLE VII. 
 
 Fragments relating to Philosophical Zoology. Selected from the 
 Works ofK. E. VON BAER. 
 
 [THE translator feels some apology necessary for the present 
 departure from the principle which ordinarily guides the Edi- 
 tors of the Scientific Memoirs ; the principle, that is, of repro- 
 ducing the work translated in its entirety and completeness. 
 
 There were two objections to pursuing this course with von 
 Bar's writings. In the first place they are voluminous, and in the 
 second, they are between twenty and thirty years old ; so that 
 they would have required notes and corrections as voluminous 
 as themselves to bring them, in matters of detail, up to a level 
 with the present state of our zoological knowledge. 
 
 On the other hand it seemed a pity that works which embody 
 the deepest and soundest philosophy of zoology, and indeed of 
 biology generally, which has yet been given to the world, should 
 be longer unknown in this country*. The present selections 
 have therefore been made, and it is hoped that they embody all 
 the important points of von BaVs doctrines. The translator will 
 be more than gratified, if yet, during the lifetime of the vener- 
 able author, he should be the means of assisting to place in its 
 proper position the reputation of one who had in the completest 
 manner demonstrated the truth of the doctrine of Epigenesis 
 three years before the delivery of Cuvier's Leqons sur I'Histoire 
 des Sciences Naturelles (in which he still advocates the Evolution 
 theory) ; and who had long recognized development as the sole 
 basis of zoological classification, while in France Cuvier and 
 GeoiFroy St. Hilaire were embittering one another's lives with 
 endless mere anatomical discussions and replications, and while 
 in Germany the cautious study of nature was given up for the 
 spinning of Natur- Philosophies and other hypothetical cobwebs.] 
 
 * Dr. Carpenter (Principles of General Physiology) is, so far as we know, 
 the only English physiologist who has publicly drawn attention to Von Bar's 
 philosophical writings. 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 I. The Relations of Affinity among the Lower Forms of Animals. 
 
 [From the Beltrdge zur Kenntmsa tier niedern Thiere, von K. E. VON BAER, 
 Nova Acta Physico-Medica, 1826, t. xiii.] 
 
 From the time when the author of these essays first began to 
 occupy himself seriously with the study of the animal world, he 
 thought he could observe that the ordinary conception of the 
 mutual relations of animal forms was not true to nature, and 
 peculiar views concerning the so-called affinities of animals arose 
 in his mind. So far back as the year 1819, he began to print 
 these views, but ceased his attempt when he had reached the 
 fourth sheet, partly because the development of these principles 
 led him further than he had expected, partly because he desired to 
 make further personal investigations. Since that period, how- 
 ever, his conception of the mutual relations of animal forms, 
 remaining fundamentally unchanged, has more and more per- 
 fected itself. This is not the place, nor is there sufficient room 
 here to demonstrate it completely, for the proving of the prin- 
 ciple appears to him to be at present the chief matter, which is 
 impossible without entering into the essential peculiarities of 
 animal structure and their relations to the rest of nature, by 
 w : hich they are conditioned and rendered intelligible. However, 
 the results of the preceding investigations have led him to re- 
 lations of affinity w r hose truth will not be granted so long as 
 another system of animals is regarded as perfectly natural and 
 true. Hence, as a corner-stone to the preceding treatises, it 
 seems advisable to attempt a clearing up of the so-called affi- 
 nities of animals. (p. 731, 732.) 
 
 If we take any one of the principal forms of invertebrate ani- 
 mals, we find it in many stages of development, and descending in 
 a more or less uninterrupted series down to the Protozoa. Even 
 the vital characteristics which are manifested in the higher 
 grades, are indicated in their first commencement. The elon- 
 gated Vibriones, the prototypes of the Naidae and Nematoid 
 Worms, and with these of the Insects, are distinguished by their 
 swift and uninterrupted movements beyond all other Infusoria. 
 We must, however, take care not to confound the Bacillaria, 
 which to us appear to be true plants, with the Vibriones. The 
 Paramacia, prototypes of the Trematoda, shorter and broader 
 
 SC1EN. MEM. Nat. Hist. VOL. I. PART II. 12 
 
178 K.E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 than the Vibriones, are less active, but very much surpass in 
 this respect the globular Volvoces with their allies. The lower 
 animals teach us, what we have already learnt from the chaotic 
 dwellers in the Mussels, that the kind of movement (which is 
 here almost the only manifestation of life) depends upon the 
 form of the body ; thence a duplex movement where the body, 
 as in the Cercarice, is composed of two forms. On this account 
 indeed, Miiller's characters for the genera of the Infusoria, which 
 are taken, not from the general figure of the body, but from 
 non-essential organs, hairs and spines, are so little fitted to 
 yield natural groups, and leave us in want of an altogether 
 new nomenclature, and of new definitions of the genera. 
 
 In order to obtain a just insight into the mutual affinities of 
 animals,it is before all things necessary to distinguish the different 
 types of organization from the different grades of development, 
 The general neglect of this distinction seems to us to have led to 
 the strangest approximations. We have theCephalopods supposed 
 to form a transition to Fishes, and the Echinoderms connecting 
 Polypes with Intestinal Worms. But metamorphose a Cepha- 
 lopod as you will, there is no making a fish out of it, save by 
 building up all the parts afresh. Granting that the Cephalopoda 
 are the most developed Mollusks, and that the Fishes are the 
 least developed Vertebrata ; and that therefore there is a certain 
 approximation between them, so far as regards the degree of 
 development ; yet to the unprejudiced eye they present no closer 
 affinity, L e. agreement in formation. Can it be denied that a 
 Pike is infinitely more similar to Man than a Sepia ? As little 
 can we recognise any affinity between the Starfish and the Tape- 
 worm. In the former the repetition of structure is successive 
 in a circle, in the latter in a longitudinal direction. That is the 
 sole agreement. But even in this there lies a contrast. 
 
 Our persuasion, that the grades of development must be 
 distinguished from the types of organization, is founded upon 
 the following considerations : We know that all the functions of 
 the perfect animal body contribute to a general result, to the 
 life of the animal ; but also that the general mass manifests the 
 total life (for animal life is always a totality) ; that the albuminous 
 jelly of the Polype digests, breathes, contracts, feels, and pro- 
 pagates ; that, however, all these functions go on as it were in 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 common, or but slightly isolated, just as the whole mass of the 
 body is a homogeneous mass. With a greater separation and more 
 complete independence of these functions is combined a greater 
 differentiation of the body into organic systems, and of these 
 systems again into separate more individualized sections. In 
 this consists the higher development of the animal body. 
 
 But the mode in which these organs of the animal body are 
 united together, is a wholly distinct matter. And it is to this 
 manner in which the organic elements are combined that we 
 give the name of Type. Every type may be. manifested in 
 higher and lower degrees of organization; the type and the 
 grade of development together determine the special forms. 
 Therefore for every type there exist grades of development which 
 here and there form considerable series indeed, yet which are in 
 no uninterrupted succession of development, and are never equal 
 through all grades. 
 
 Although then, in the following pages we speak of certain 
 series of grades of development, we are far from wishing to 
 assert any equal distribution of forms through these. On the 
 other hand, we think it obvious that the assumption of any such 
 corresponding affinities among organic forms does violence to 
 nature. Whatever such scheme may have been devised, it 
 cannot be discovered by the unprejudiced observer. If such a 
 correspondence be deduced a priori from the harmonious ope- 
 ration of nature, we may demonstrate with equal justice and 
 force that among men A must have as many relations as B, be- 
 cause such equivalency of relationship is contained in the idea 
 (denkbar], and therefore must be ; and that if B even gave out he 
 had fewer brothers, they would nevertheless be discovered some 
 day or other. It appears to us that here the necessarily regular 
 occurrence of the phaenomena has been confounded with their mu- 
 tual equivalency. For instance, to resume the comparison which 
 the word affinity has suggested : as the small number of children 
 in a family is not a matter of chance, but depends upon the 
 slight fecundity of the parents ; so it is no chance or whim of na- 
 ture that certain animal forms are realized in fewer variations, 
 and exhibit fewer deviations than others. The reason must lie 
 in the nature of these forms. Certain combinations of organic 
 parts are, to speak metaphorically, more natural than others. A 
 
 12* 
 
180 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 bird's beak must be more in harmony with a bird's body and 
 more easily combined with it, than with a mammalian body, arid 
 still less with a frog's body ; for with a multitude of beaked 
 birds, we have only a couple of beaked mammalia, and no beaked 
 frog at all. Here we have, not to interpret, but to conceive 
 what actually exists. 
 
 We see in fact, that certain principal models of the animal 
 kingdom become modified among various animals, not however 
 equally, but in such a manner that the majority of these modi- 
 fications are more closely allied than the rest. The principal 
 models may be called Provinces of the animal kingdom, and their 
 most important modifications, Classes ; these being again mo- 
 dified into subordinate forms, Families, and so forth. It happens 
 always, however, that among the subordinate modifications of 
 any degree, the majority resemble one another, and only a 
 few diverge ; so that the organic theme with its variations may 
 be compared to a sphere composed of a densely compressed 
 centre and a much more thinly populated atmosphere. Upon 
 the same relations again depend what we call genus and species. 
 The species consists of a number of individuals, which are indeed 
 not perfectly similar, but most of which exhibit an obvious 
 similarity ; whilst a few are often so aberrant, that it might be 
 seriously doubted whether they are to be grouped under this 
 form or not. These aberrations, however, are not only rare, but 
 Nature affords them less support, so that they continually tend, 
 either in themselves or in their progeny, to return to the normal 
 standard. There are, further, two remarkable laws : the first, 
 that the more dense the centre, the less extensive is the atmo- 
 sphere, as well in the larger spheres as in the smaller subordinate 
 ones. So even in the species. If the individuals which may be 
 unquestionably referred to one species, yet differ a good deal 
 from one another, then the number of those concerning which 
 well-founded doubts may be entertained, is not inconsiderable. 
 The more similar, on the other hand, the normal individuals are 
 to one another, so much the less frequently, or even not at all, 
 do the transitional forms occur. Secondly, in every larger 
 sphere the subordinate spheres of the centre are richer in se- 
 condary forms than the sphere of the periphery. In fact, if we 
 take single species, we find that they are the more rich in indi- 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 181 
 
 viduals, and the more extensively scattered over the earth's 
 surface, the more closely they are connected with the centre of 
 a sphere of modification. 
 
 What has been said may be made more intelligible by exam- 
 ples. I choose them from among the Vertebrata, and, indeed, 
 from the higher classes, because our acquaintance with these is 
 least defective. The Mammalia differ so much from one an- 
 other, that without anatomical examination they could hardly 
 be recognised as modifications of one principal form. Their 
 centre is evidently formed by the proper quadrupeds, while the 
 climbers (Quadrumana), the fliers (Cheiroptera), the swimmers 
 (Cetacea), and lastly the Monotremata, represent the atmosphere, 
 or the aberrant forms. The proper quadrupeds even present 
 considerable differences from one another ; still more do the 
 peripheral forms differ from one another and from the central 
 forms. They considerably approach other principal forms, with- 
 out however truly passing into them ; for the organization of 
 the most aberrant forms, the Ornithorhynchus and the Whale, 
 is still so far removed from that of a true fish or amphibian, 
 that we can decide with certainty to which class they belong. It 
 is otherwise with Birds. All the orders are so similar in their 
 essential relations, that we find them as it were crowded 
 round the centre, and only the Ostrich with a few other birds 
 can be regarded as the peripheral members of this very con- 
 densed sphere. These peripheral members again do not de- 
 viate so far from the principal forms, but that the hastiest 
 inspection is sufficient to leave no doubt on the mind, whether 
 they are beasts or birds. Enclosed within these narrow bounds, 
 the number of Birds is yet at least six times as great as that of 
 the Mammalia. The peripheral forms among Birds are to the 
 central forms, hardly in the proportion of 1 to 1000 : in the 
 Mammalia they form more than one-fourth (!) of the whole. If 
 we turn to the subordinate spheres, we find in the centre of the 
 Mammalia a few families whose normal genera are very similar 
 to one another, as the Ruminants. Here the number of the 
 peripheral forms (the hornless Ruminants) is not only small, but 
 they are likewise few and scattered in the world (Camels are 
 multiplied only by human aid), in comparison with the herds of 
 Antelopes, Deer, and Oxen. The Carnivora, whose centre is 
 
182 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 formed by the Cats, Hyenas, Dogs, Viverridae, and Weasels, 
 are much more unlike one another, and so form a less con- 
 solidated sphere than the Ruminants. So much the more nume- 
 rous and more nearly approximated to other families are their 
 transitional forms, by which in the Potto they approach the 
 Quadrumana ; in the Insectivora, the Rodents ; in the Fish 
 the Otter, the Seal and the Walrus, the Cetacea ; in the Marsu- 
 pialia, the Monotremata ; and these transitional forms are upon 
 the whole far poorer in individuals than the aberrant forms of 
 more narrowly limited families. The Rodents present nearly 
 the same peculiarities. Among the proper quadrupeds the least 
 consolidated sphere is that of the Pachydermata, which, however, 
 in relation to the small number of those forms which can be 
 considered central, has many aberrant members, the Daman, 
 the Elephant, the Solidungulata ; and in the ancient world there 
 were yet more. Among Birds the transitional forms are more 
 solitary genera, the Ostriches and Cassowaries, which under the 
 influence of the more consolidated centre are only single mu- 
 tually divergent groups. Among the Mammalia, where even the 
 central forms are not so closely arranged, the transitional or atmo- 
 spheric groups themselves compose considerable spheres. The 
 Quadrumana, a transition to Man, form a numerous order, whose 
 centre is constituted by the true Apes ; while the Makis, the 
 transition to the proper quadrupeds, form single small scattered 
 families. Not so the Bats, for which the genera Pteropus, and 
 still more Galeopithecus, are transitional forms. Most distant 
 from the centre of the proper quadrupeds are the Monotremata ; 
 and in accordance with this we find that they contain but few 
 genera, among which considerable differences exist, and that even 
 the species are represented by but few individuals. If we glance 
 at the Amphibia, we find that the members of the most aber- 
 rant group, the Sirenidae, are not only more dissimilar from one 
 another, than, for example, all the tail-less Batrachia which oc- 
 cupy the centre are, but that their occurrence is limited to a 
 few places. 
 
 Do not these considerations show that the Idea of animal or- 
 ganization does not vary at equal intervals, but, as we observed 
 above, is realized in certain principal forms which again break 
 up into variations of a lower grade, in such a manner that the 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 183 
 
 variations are more or less closely accumulated around a given 
 centre, according to the peculiar nature of each standard form ? 
 It follows at once from this that the transitions are more indi- 
 cated than realized, that they are very unequally distributed, 
 and that they never form an even progression ; for at the limits 
 of two spheres, the most similar members of each are far more 
 remote from one another than they are from their own centres. 
 
 The conception of spheres does not exclude that of series ; on 
 the other hand, the different types, since a manifold degree of 
 development occurs in them, will necessarily arrange themselves 
 in series, which however again consist of spheres, radiating from 
 whose centres every single form varies in many directions. 
 
 Four principal types appear distinctly to manifest themselves j 
 the type of the elongated, Articulated animal, the type of the 
 Radiate animal, the type of the Mollusk, and that of the Ver- 
 tebrate animal ; the latter unite the articulate and molluscous 
 type together in their animal and vegetative organs. Indeed 
 one might perhaps recognise in the head an outline of the ra- 
 diate type, since here in the course of further development all 
 parts become more and more collected around a central point. 
 Besides this, in any case the central portion of their nervous 
 system is something peculiar which is wanting in other animals ; 
 for which reason the Vertebrata cannot descend to the lowest 
 grades of organization. 
 
 It will be seen that we have here arrived at the four principal 
 divisions of the animal kingdom established by Cuvier. We 
 believe, in fact, that Cuvier has penetrated most deeply into the 
 relations of animal organisms. But he does not satisfy us in 
 this ; that he requires in the Mollusca and Articulata not only 
 the type of their organization, but also a certain degree of deve- 
 lopment, a condition which can only be required of the single 
 classes. The consequence is, that all the animals of low organi- 
 zation are thrown among the Radiata, although very many of 
 them are by no means radiate in their structure. The bounda- 
 ries under these circumstances could only be drawn arbitrarily. 
 If Gordius belongs to the Articulata, why should not Filaria and 
 Vibrio ? It seems plain to us that the conditions which predo- 
 minate in this type may be traced down to the lowest stages of 
 organization ; only we must not require from these prototypes, 
 
184 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 that the special details of the parts, i.e. of the intestinal or ner- 
 vous systems, resemble what is found in the higher grades ; for 
 the intestine and the nervous system themselves are not always 
 present; it needs only that the general character should be re- 
 cognised. We thus obtain principal series between which again 
 subordinate ones are found, according as in them the character 
 of one type is more or less mixed up with that of another. These 
 series again send out offshoots, and by no means always take a 
 rigidly straight course, since every series is fundamentally only a 
 number of spheres. After what has been said, it will cause no 
 astonishment if we neither make the series equally perfect, nor 
 draw them out to an equal length. It seems to us rather, that 
 there is evident reason why gaps must exist here and there 
 (pp. 738-747). 
 
 What do we gain, however, by this view of the lower forms 
 of animals ? We ask in the name of the reader. We gain, 1 
 believe, a great deal. 
 
 In the first place we safely base the conviction, that all the 
 forms of animals are by no means to be considered as uni- 
 serial developments from the lowest to the highest grade of per- 
 fection. Although from the Vibrio to the Butterfly intermediate 
 forms occur, though not at equal intervals, nor of equal deve- 
 lopment, which manifest in their form and life the grades of a 
 common character, yet no starfish nor shellfish can be in- 
 truded without completely destroying the fundamental concep- 
 tion of a genetic connexion. The same relations are repeated 
 in many fundamental types. In order to show at once the ap- 
 plication of our views to special investigations, we must call to 
 mind that the metamorphoses of animals in time have been com- 
 pared with the stages of development considered as isolated, or 
 the so-called metamorphosis in space. It has been concluded by 
 a bold generalization from a few r analogies, that the higher animals 
 run in the course of their development through the lower animal 
 grades, and sometimes tacitly and sometimes expressly they have 
 been supposed to take their way through all forms. We hold 
 this to be not only untrue, but also impossible. The general 
 type appears to us to be always unchanged, and we observe that 
 animals in the course of their development are more or less simi- 
 lar only to lower stages of the same type. The insect may per- 
 
K. E, VON BAER. PHILOSOPHICAL FRAGMENTS. 185 
 
 haps resemble a Vibrio or a Thread-worm ; but never a Medusa 
 or an Ascidian. In the Vertebrata, indeed, it has been attempted 
 to demonstrate an agreement with Medusae in the distribution 
 of the vessels in the germinal membrane ! Here the only thing 
 overlooked was the body of the embryo. In this the essential 
 character of the type is the first to arise; the formation of the 
 vertebrate animal begins with the rudiment of the vertebral 
 column, proceeding from which the dorsal folds pass up- 
 wards and the visceral plates downwards, so as to lay the founda- 
 tions of the upper and lower halves of the body, which charac- 
 terize this form. 
 
 Our view explains also, how the external forms of animal 
 bodies are connected with their vital manifestations, and with the 
 arrangement of the internal parts. The separate organic ele- 
 ments develope themselves into a higher state of perfection by 
 differentiation of the animal substance. Their form and con- 
 nexion, however, depend upon the type which predominates in 
 the animal, or in a principal part of it. Hence from the form of 
 the exterior one can conclude the arrangement of the interior. 
 If we examine, for instance, an Octopus, we see the molluscous 
 structure only in the sac-like part of the body, while in the head 
 the motor organs are arranged in a completely radiate manner 
 around a central point. In the middle is the aperture of the 
 mouth, and it corresponds completely with the type of the ra- 
 diate animal, that the nerves and vessels, before they pass into 
 the separate arms, are combined into a circle in the median disc. 
 We know again that the Cephalopoda most frequently swim with 
 their heads directed downwards ; the radiate portion of the body 
 therefore seems to hold and to move itself in accordance with 
 the mode of locomotion prevalent in its type, overcoming the 
 tendency of the molluscous body. Even in the higher animals 
 we find that when single parts take on the external form of the 
 radiate type, we have a corresponding order of the nerves and 
 vessels. Thus it is with the iris of the Vertebrata. 
 
 Furthermore, our conception explains how, according to the 
 nature of the different types, a given organ arises, and becomes 
 developed earlier in one than in another ; how it is again that 
 the perfection of a single organ does not imply a general corre- 
 spondence in development. It is one of the characters of our 
 
186 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 first type that the principal vascular trunks are tubes, and a 
 true sharply defined heart appears only very late in the already 
 modified form of the Decapoda. In the radiate type we have 
 rings united by a perpendicular vessel. In the molluscous type, 
 in which there is a general tendency to the formation of vesicles, 
 the central point of the organization naturally appears earliest as 
 a distinct heart. The French zoologists then are greatly in 
 error in regarding the Mollusca from this organ alone as more 
 highly developed than the Insects, and in placing the Acephala 
 above the Bees. 
 
 Finally, this idea enables us to comprehend how the general 
 form of the type depends upon the productive conditions (zeu- 
 genden momenten), W 7 hile the inner development depends espe- 
 cially upon the nature of the animal. Perhaps these considera- 
 tions may be profitable if they be kept in view in the course of 
 investigations into the course of development. 
 
 II. On the Development of Animals, with Observations and Re- 
 flections. By Dr. K. E. VON BAER, Konigsberg, 1828. 
 
 [Ueber Entwickelungs-Geschichte der Thiere, von Dr. K. E. VON BAER. 
 4 to, 1828.] 
 
 THE FIFTH SCHOLIUM. On the relations of the forms which 
 the individual takes in the different stages of its development, 
 pp. 199-264. 
 
 1. The prevalent notion, that the embryo of higher animals 
 passes through the permanent forms of the lower animals. 
 
 The relation of the forms which the embryo gradually assumes 
 has already been referred to in its proper place in the course of 
 the exposition of the mode of development of the chick. The 
 importance of the subject, however, and the interest with which 
 it has lately been regarded, lead me to think it fitting and ne- 
 cessary to undertake a special investigation of these relations, 
 since they appear to me to be somewhat different from what the 
 general opinion represents them. In order to be clearly under- 
 stood in developing my own views, and to bring forward more 
 distinctly their essential features, I must be permitted first to 
 explain the prevalent mode of conceiving the progress of the 
 development of the embryo. 
 
 Few expressions of the relations of organized beings have met 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 187 
 
 with so much applause as this : that the higher forms of animals 
 in the single stages of the development of the individual, from its 
 first origin to its completed development, answer to the permanent 
 forms of the animal series, and that the development of each ani- 
 mal follows the same laivs as that of the whole animal series ; 
 thai therefore the more highly organized animal in its individual 
 development passes essentially through the permanent forms which 
 lie beloiv it, so that the periodical differences of the individual 
 may be referred to the differences of the permanent animal forms. 
 
 This idea, springing into existence at a time when no con- 
 nected investigation (except those of Malpighi and Wolff) into 
 the earlier periods of development of any animal had been in- 
 stituted, and principally carried out by a man who perhaps pos- 
 sessed more knowledge than any one else of the course of de- 
 velopment of the higher organisms, could not fail to be widely 
 accepted, since it was supported by a multitude of special de- 
 monstrations. It acquired yet greater influence, by its fruitful 
 application to the explanation of a series of monstrosities, which 
 were regarded as the consequences of a partial arrest of deve- 
 lopment in its earlier periods. It is no wonder then that it was 
 warmly received and rigorously carried out. 
 
 Certain of its advocates were so zealous, that they no longer 
 spoke of similarity, but of perfect identity, and assumed that the 
 correspondence had been demonstrated in all cases and to the 
 minutest details. A short time since we read in a paper upon 
 the circulation in the embryo, that there was no animal form 
 through which the embryo of man omitted to pass. By degrees 
 it became the custom to look upon the different forms of animals 
 as developed out of one another, and then many appeared to 
 forget that this metamorphosis was after all only a mode of con- 
 ceiving the facts. On the strength of the observation that no 
 vertebral remains are to be found in the older strata, it was con- 
 cluded that there was historical evidence for such a metamor- 
 phosis of the different forms of animals, and at length, in sober 
 seriousness, and with all due particularity, we were informed 
 exactly how they arose from one another. Nothing could be 
 easier. A fish, swimming towards the shore, desires to take a 
 walk, but finds his fins useless. They diminish in breadth for 
 want of use, and at the same time elongate. This goes on with 
 
188 K. E. VOX BAER. PHILOSOPHICAL FRAGMENTS. 
 
 children and grandchildren for a few myriads of years, and at 
 last who can be astonished that the fins become feet ? It is still 
 more natural that the fish in the meadow, finding no water, 
 should gape after air, thereby, in alike period of time, deve- 
 loping lungs ; the only difficulty being that in the meanwhile a 
 few generations must manage to do without breathing at all. 
 The long neck of the heron arose from a habit its ancestors ac- 
 quired of stretching out their necks for the purpose of catching 
 fish. The young ones in consequence came into the world with 
 their necks something the longer, and cultivated the same trick, 
 transmitting to their posterity still longer necks, whence we 
 may fairly expect, that when the world is getting very old, the 
 herons 5 necks will be past measuring altogether. 
 
 An immediate consequence of the assumption of this idea as 
 a natural law was, that a view which had once been very gene- 
 ral, but had subsequently been pretty generally given up that 
 of the universal progression of the different forms of animals 
 gradually got footing again ; and though not often asserted in 
 so many words, nay, perhaps unconsciously to naturalists them- 
 selves, it became admitted in discussions concerning animal 
 forms. It must be confessed that the natural law being as- 
 sumed, logical consequence required the admission of the view 
 in question. There was then only one. road of metamorphosis, 
 that of further development, either attained in one individual 
 (individual metamorphosis] , or through the different animal forms 
 (the metamorphosis of the animal kingdom] ; and disease was to 
 be considered as a retrogressive metamorphosis, because univer- 
 sal metamorphosis, like a railroad, allows motion backwards or 
 forwards, but not to one side. 
 
 From such applications, opposed at once to unprejudiced in- 
 vestigation and to exact knowledge, the more cautious indeed, 
 and before all that advocate of the principle through whose name 
 it attained the widest assent, carefully abstained ; but it cannot 
 be denied that they were the logical consequences of the law, 
 and thence a sufficient ground of distrust*. But the attacks of 
 
 * It did not appear fitting here to give a detailed account of this theory, 
 for the purpose of attempting to refute it. Since a certain contradiction ap- 
 peared perceptible enough in Nature, it has been carried out by different men 
 very differently. Those who were best provided with special knowledge were 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 189 
 
 its adversaries were partly directed only against the exaggerations, 
 partly were weak in not being supported by careful personal 
 observation of the development of the same animal form. 
 
 A few exceptional cases can have but little weight, unless a 
 completely new doctrine can be substituted. The gradual de- 
 velopment of the embryo out of a delicate homogeneous mass, 
 called to mind so strongly the construction of the body of the 
 lowest animals, that all objections appeared wasted against un- 
 important minutiae, so long as the attempt was not made, re- 
 cognizing this agreement, to demonstrate another and a differ- 
 ent relation. 
 
 Quite recently, in fine, the doctrine of the agreement of in- 
 dividual metamorphosis with the ideal metamorphosis of the 
 whole animal kingdom obtained an additional importance, by 
 llathke's brilliant discovery of gill-clefts in the embryos of Mam- 
 mals and Birds, in which very soon afterwards the appropriate 
 vessels were found. 
 
 always more cautious and indefinite, while those who followed them were much 
 more decided. The whole doctrine appears to me to be more a phase of the 
 development of natural science than the property of any single man. Different 
 degrees of development were observed in the different forms of animals. It 
 was recognized that these animal forms are to be considered as modifications 
 of one another. It was natural, in fact necessary, that the attempt should be 
 made to carry out the simplest mode of conceiving these modifications, that all 
 forms are immediately developed out of one. The assumption of this develop- 
 ment as an historical fact, can be considered but a small step further, and is a 
 logical deduction ; a comparison with individual development came necessarily 
 into the same circle of ideas ; and in any case it is a service to have made the 
 experiment how far our knowledge of development can be introduced therein. 
 With the full conviction that the view in its whole extent is a necessary 
 transitional phase of our knowledge of nature, it seemed unnecessary to the 
 short exposition given above, to follow an exact chronological order. Many 
 of the attempts indicated, to show the development of the classes of ani- 
 mals one out of the other, are older than the more important endeavours to 
 refer the stages of development of the embryo to the class-differences. All 
 this I know very well, and I expect no objections on this head. I chose only 
 the shortest mode of exposition. The whole circle of ideas, which I here hope 
 to define more exactly, by drawing attention to the distinction between the 
 higher and lower stages of development of the animal body and the type of 
 organization, has so large a share in all investigations, that we meet with it in 
 a very great number of works, and it is therefore quite unimportant to make 
 a selection here. 
 
190 K. E. VOX BAER. PHILOSOPHICAL FRAGMENTS. 
 
 2. Doubts and Objections. 
 
 At an early period my attention was directed to the mutual 
 relation of the permanent forms of animals ; and the first thing 
 that appeared obvious to me was, that this relation could in 
 nowise be considered as a uniserial progressive development. 
 But a uniserial progressive development, if only as a logical 
 conception, appears to be absolutely necessary for the permanent 
 forms of animals, if they are repeated in the development of the 
 individual. 
 
 I therefore regarded this doctrine with mistrust, and kept it 
 constantly in mind in investigating the development of the chick, 
 in the persuasion that the continued observation of the develop- 
 ment of a single species of animal must yield a more certain 
 decision than a multitude of single unconnected comparisons. 
 As, however, my observations convinced me that the essential 
 character of the vertebrate animal arises very early in the chick, 
 and regulates the whole course of its development, I so early as 
 the year 1823 expressed my doubts in the form of an academical 
 disquisition*. Nevertheless it seemed fitting not to speak pub- 
 licly concerning them until 1 could present a series of observa- 
 tions. My conviction with regard to that law, indeed, was more 
 a negative one. I now believe that I can replace it by another ; 
 and the first part of this collection offers, I think, a proper op- 
 portunity for the development of the latter. 
 
 It will not be superfluous first of all to bring forward a few 
 objections to the view just alluded to, which might be drawn 
 from the previous investigations of embryos, and which might 
 serve to raise doubts in the minds of those readers who are com- 
 pletely devoted to it. Not attempting a complete development 
 of these doubts, I shall content myself with a few brief indi- 
 cations. 
 
 In the first place, I was led to reflect, that we know the de- 
 velopment of hardly any but the highest forms, the development 
 of Mammalia (including Man) and that of Birds. In whatever 
 
 * Dissertatio de fossilibus Mammalium reliquiis. Regiomont. 1 823, 4to. To' 
 which is appended the thesis, Legem a natures scrutatoribus proclamatam, evo- 
 lutionem quam prima estate quodque subit animal quam in animalium serie ob- 
 servandam putant, respondere, a natura alienum esse contendo. 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 191 
 
 circumstance their embryonic condition, therefore, differs from 
 their permanent state, if it had an analogue anywhere in the 
 animal series, it must be found almost always among the lower 
 animals. 
 
 That, however, a few correspondences should be found be- 
 tween the embryonic condition of certain animals and the perfect 
 condition of others appears to be necessary, and of no particular 
 importance. They could not be wanting, since the embryos do 
 not lie without the sphere of the animal world, and since the 
 variations of which the animal body is capable are determined 
 for each form by an internal connexion and mutual reaction of 
 its separate organs, whence certain repetitions become necessary. 
 
 To convince oneself that such a doubt is not wholly without 
 its weight, let it be imagined that Birds had studied develop- 
 ment, and that it was they who in turn investigated the structure 
 of the adult Mammal and of Man. Should we not find some- 
 thing of this sort in their physiological handbooks ? " Those 
 four -legged and two-legged animals have much resemblance to 
 embryonic forms, for their cranial bones are separated, arid they 
 have no beak, just like us during the first five or six days of in- 
 cubation : their extremities are a good deal alike, as ours are for 
 about the same period ; there is not a single true feather over 
 their whole body, but only delicate feather- shafts, so that we, as 
 fledgelings, are more advanced than ever they are ; their bones 
 are hardly at all brittle, and like ours during youth contain no 
 air at all; they have no trace of air-sacs, and their lungs are not ad- 
 herent, like ours at the earliest period ; they have no crop ; their 
 proventiculus and gizzard are more or less compounded into a 
 single sac ; evidently arrangements which in us are only trans- 
 itory, and the nails are in most of them as clumsily broad as in 
 us before we break the shell ; the Bats alone seemingly the 
 most perfect among them have any power of flight, which is 
 quite absent in the rest. And these Mammals, which for so 
 long a period after birth cannot find their own food, and which 
 are unable to raise themselves from the earth, must pretend for- 
 sooth that they are more highly organized than we !" 
 
 If it be a law of nature that the development of the individual 
 essentially consists in passing through the permanent forms of 
 lower animals, it must follow 
 
192 K. E. VOX BAER. PHILOSOPHICAL FRAGMENTS. 
 
 1. That no conditions can obtain in embryos which are not 
 permanent in at least some animals. There exists, however, no 
 animal which carries about its nutriment with it, as the embryo 
 carries its yelk. No animal has a protruded portion of the in- 
 testine, such as the yelk-sac. But from the development of 
 Birds, and of some Mammalia (especially of the Carnivora), in 
 which this yelk-sac remains for a very long period, up to a time 
 when all the characters of the Bird's or Mammal's body are 
 either fully present or nearly so, we ought to conclude that many 
 such animals exist. Among Mammals the incisor teeth are 
 developed before any others. No animal, however, has a per- 
 manent dentition consisting of incisor teeth only. 
 
 2. In like manner, however, as the relations of the embryo 
 produce forms in it like the protruded intestinal sac, which 
 occur in no permanent animal, do they render it impossible that 
 many large groups of animals should be repeated. Thus the 
 essential characters of Insects, their active relation to air, cannot 
 be repeated in them ; therefore, also, the Mammalian embryo 
 can never resemble the perfect Bird. 
 
 3. Furthermore, the embryo of the higher animals, in any 
 stage of its development, should not agree with a single character 
 only of some permanent form, but with its totality, even although 
 the peculiar relations of the embryo should exclude certain cor- 
 respondences. If it be argued, for instance, that certain cha- 
 racters must be peculiar to, and permanent in, the embryo as 
 such ; that, for example, it is only because as an embryo it is 
 dependent for nourishment upon the maternal body, that it has 
 a protruded yelk-sac, and in this respect cannot correspond with 
 a permanent form ; yet those relations in which there is an 
 agreement here and there* must be common to all. This, how- 
 ever, is not the case. If I ascribe to the embryo, so long as its 
 two cardiac ventricles are not yet separated, and the fingers are 
 not divided from one another, the organization of a Fish, yet I 
 find no compressed tail, nor a thousand other characteristics 
 which very early appear in Fishes. 
 
 It is just the same with whatever permanent animal form I 
 compare the embryo of a higher form. It is said that the Ce- 
 tacea are foetus-like (i. e. resemble the embryos of higher animal 
 * i. e. which are not necessarily connected with embryonic existence ? TR. 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 193 
 
 forms), because their testes are contained in the abdomen, be- 
 cause some of them have no true teeth, because the anterior and 
 posterior sphenoids remain separated, &c. &c. But the other 
 cranial bones of the Cetacea unite very early and very closely, 
 and therefore are adult-like. Their jaws are very long, although 
 all Mammalia, the Cetacea included, have their jaws the shorter 
 the younger they are. The separation of the cranial bones, how- 
 ever, is no especial peculiarity of the embryonic condition, which 
 is absent in the adult condition of the lower classes of animals ; 
 for in Fishes it is brought forward again as an embryonal con- 
 dition that the cranial bones are divided into many portions, and 
 are merely applied to one another, although at the base of the 
 skull the unity of the sphenoid the very opposite of what occurs 
 in the Cetacea offers, on the other hand, a resemblance with 
 the adult condition of the highest Mammalia. Agreement with 
 a Fish or with a Cetacean is therefore no absolute condition for 
 the organization of the embryo. 
 
 4. If the law we are engaged in investigating were correct, no 
 conditions which are permanent only in the higher animals 
 could be a transitory stage in the development of particular 
 lower forms. But a great number of such conditions are de- 
 monstrable. We cannot indeed discover them in the course of 
 human development, since we know no higher organization. 
 But the Mammalia afford examples enough. In all the jaws are 
 at first as short, as they are permanently in Man ; the parietal 
 ridge is developed very late in animals which are provided with 
 it, while, on the other hand, it is wanting in the highest forms. 
 Instances of this kind multiply the further we descend. We 
 have already introduced Birds speaking, in order to insist upon 
 a multitude of previously-known relations in which the embryo 
 of the Bird agrees with the adult Mammal. We can bring for- 
 ward still more. The brain of Birds in the earliest third of em- 
 bryonic life is much more similar to the brain of Mammals than 
 in the adult condition. The corpora quadrigemina have not de- 
 scended, the olfactory bulb is hollow and thick, and there is 
 even a kind of fornix present. The heel of the Bird developes 
 itself from many cartilages into a single bone. The eyes in the 
 Chick are at first placed nearer together than subsequently, and 
 give it a humanized face. Young Lizards have a very large 
 SCIEN. MEM. Mi*. Hist, VOL. I. PART III. 13 
 
194 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 brain. The larva of the Frog has a true beak like Birds, and 
 before it loses its tail an intestine of a length such as is only 
 to be found permanently in a few forms of Mammals. The Frog 
 larva is at first tail-less, a condition that occurs only among the 
 highest Mammals ; even the adult Frog has an internal tail, for 
 we must so designate its long caudal vertebra. The Myriapods, 
 the Mites, and the Hydrachne have, when they creep out of the 
 egg, only three pair of feet, like the perfect condition of Insects 
 which undergo metamorphosis. Even if, contrary to my opinion, 
 it be maintained that the Arachnida are more highly developed 
 than the true Insects, yet every one will allow that Insects with 
 a metamorphosis are higher developments of the Myriapoda. 
 Such cases as these should by no means occur, if the develop- 
 ment of the higher animals consisted in passing through the 
 forms of the lower ones. 
 
 5. We ought to see the organs or larger apparatuses make 
 their appearance in the different classes of animals in the same 
 manner as they are developed in the embryos of higher animals, 
 if we consider the former to be developed out of one another ; 
 this, however, is by no means the case ; the posterior extremity is 
 in most Fishes only perfect in its terminal member, while in the 
 embryo of the higher animals the proximal joint is first formed. 
 
 6. Lastly, such parts as are found only in the higher animals 
 should arise very late in the course of development. But it is 
 not so. A few portions of the vertebral column, its centre and 
 arches, exist earlier in the Chick than every other part. How 
 then can the Chick ever have any similarity with an invertebrate 
 animal ? 
 
 This remark, however, leads us nearer to our purpose, and 
 therefore at this point the attempt to discover the true relation 
 may be made. 
 
 3. On the Mutual Relations of the different permanent Forms 
 
 of Animals. 
 
 In order to investigate the essential relations of the metamor- 
 phoses which occur in the development of the individual, I 
 must premise a sketch of the different forms of animals. I have 
 already in part treated of this subject in another place (Nova 
 Acta Acad. vol. xiii. part ii. pp. 739-762) ; but since the re- 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 195 
 
 marks which I have there made find their application here, and 
 since besides it is accessible to but few, I shall not hesitate to 
 prefix an extract from that essay for the purpose of building 
 further upon it. 
 
 I wish before all things to draw attention to the distinction 
 between the grade of development of an animal and the type of 
 its organization. The grade of development of an animal con- 
 sists in the greater or less heterogeneity of its elementary parts 
 and of the separate divisions of a complex apparatus ; in a word, 
 in its greater histological and morphological differentiation. The 
 more homogeneous the whole mass of the body is, so much the 
 lower is the grade of its development. The grade is higher 
 when nerves and muscles, blood and cell-substance, are sharply 
 distinguished. The more the elementary parts differ from one 
 another, so much the more developed is the life of the animal in 
 its various phenomena ; or rather we should say, that the more 
 various the separate manifestations of animal life, the more 
 heterogeneous are the elementary parts by which that life is 
 brought about. 
 
 It is the same with the separate divisions of an apparatus. 
 The organization is higher when the divisions of a whole system 
 or apparatus are less like one another and possess more indivi- 
 duality, than when a greater similarity pervades them. It is a 
 higher grade of development, therefore, when the difference be- 
 tween the brain and spinal cord is greater, than when the original 
 similarity is less disturbed. If we carefully discriminate between 
 this relation of higher development and the relation of type, we 
 shall readily overcome a multitude of difficulties which stand in 
 our way, while we adopt the more or less generally predominating 
 theory of a single continual line of progressive development from 
 the Monad to Man. Let us take Fishes for an example. Be- 
 cause they possess a brain and spinal cord, together with an 
 internal skeleton, and everywhere exhibit the great vertebrate 
 type, they are raised above the heads of all the Invertebrata ; 
 and it is made a matter of wonderment that Bees, and the ma- 
 jority of insects which undergo a metamorphosis, exhibit more 
 skill and a far more manifold vital activity. In Bees, however, 
 nerves and muscles are far more differentiated than in Fishes. 
 The single divisions of an apparatus or of an organic system are 
 
 13* 
 
196 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 also more heterogeneous. In most Fishes the stomach is but 
 little distinguished from the intestine, nor this from the pyloric 
 appendages. In the intestinal canal itself the large intestine is 
 often hardly distinguishable from the small. The nervous sy- 
 stem of Fishes presents a brain, which predominates but little 
 over the spinal cord. 
 
 In the Bee we meet everywhere with more heterogeneity. 
 The first coalesced pair of ganglia, although no actual brain, 
 since we can only give this name to that part of the organism 
 which forms the anterior extremity of a spinal cord, yet is far 
 more pre-eminent over the rest of the nervous system than the 
 brain of Fishes, and has more completely the signification of a 
 centre of the nervous system. I believe, therefore, that the Bee 
 is in fact more highly organized than the Fish, although upon 
 another type*. 
 
 By type I mean the relative position of the organic elements 
 and of the organs. This relative position is the expression of 
 certain fundamental peculiarities in the direction of the vital 
 activities, e. g. of the ingestive and egestive poles. The type is 
 totally different from the grade of development, so that the 
 same type may exist in many grades of development, and con- 
 versely, the same grade of development may be attained in 
 many types. The product of the grade of development with the 
 type yields those separate larger groups of animals which have 
 been called classes. 
 
 The confusion of grade of development with the type of 
 construction appears to me to be the origin of many failures in 
 classification ; and even in the obvious difference between these 
 relations lies evidence enough that the different animal forms do 
 not compose a single progressive series from the Monad to Man. 
 
 * It has long been observed, that, among allied forms, those which live in 
 water, in the development of their animal, as contrasted with that of their 
 plastic functions, are below those living on land, which exhibit more marked 
 motor and physical capacities. May not the water be the cause of this? The 
 antithesis of nerve and muscle appears not to be so decidedly developed in 
 water as when there is a more active relation with the air. The muscles are 
 softer and paler, the nerves are less white and consistent. We cannot get rid 
 of the fancy that they both look as if they were infiltrated with water. When 
 in Fishes certain muscles are remarkable for their redness, as the maxillary 
 muscles of the Sturgeon, the nerves which supply them are whiter than the others. 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 I need follow out this remark no further ; any closer examina- 
 tion will be rendered superfluous if I succeed in clearly explain- 
 ing what I mean by type. 
 
 The type then is the relative position of the parts. It may be 
 readily recognized that the different types are modifications of 
 certain archetypes (Haupt-Typeri), in which this relative position 
 is especially characterized, and that intermediate forms occur 
 which either unite the characters of the archetypes into a middle 
 type, or in which one archetype preponderates in the one half of 
 the body, in the other another. For the present I leave these 
 intermediate forms out of consideration, referring to the essay 
 which I have cited. But I must once again bring forward the 
 archetypes in this place. 
 
 I believe that four archetypes may be clearly demonstrated, 
 the peripheral or radiate archetype, the articulate or longitudinal 
 archetype, the massive or molluscous archetype, and the arche- 
 type of the Vertebrate*. 
 
 The peripheral type is exhibited by certain discoid Infusoria, 
 by the Rhizostomidae, Medusae and Asteridae. In their external 
 form superficial dimension is represented. The principal anti- 
 thesis is that of centre and periphery. The contrast of ingestion 
 and egestion lies in a direction from the centre to the circum- 
 ference. Hence the whole organization radiates from a centre. 
 Besides this, the contrasted relation of upper and lower sides 
 only is developed, and this slightly ; no distinction of right and 
 left, or of anterior and posterior, exists at all. Their movements 
 are thence without definite direction. As the whole organization 
 radiates from a centre, so the centres of all the organic systems 
 are in the middle, or are disposed circularly around the middle 
 (thus the stomach is in the middle, and round it are the nerves 
 and vascular circlets, when these parts are developed at all) ; 
 from them branches pass into the radii. In every radius is 
 repeated what exists in any one ; and every radius, if we follow 
 
 * I will not attempt to decide here, whether a peculiar type is not to be 
 recognized in those animals whose whole organization is disposed not round a 
 central point, but round an axis, as in the Holothuria. Ingestion arid egestion 
 are not here contrasted as centre and periphery, but as two ends of a line 
 around which the remaining organization is peripherally disposed. Here too 
 as a lower grade the Nematoidea might be arranged, and perhaps other lower 
 forms. 
 
198 K. E. VON BAER. -PHILOSOPHICAL FRAGMENTS. 
 
 it up to its centre, takes a similar share in the central parts also 
 (the urinary system alone appears to make an exception), so that 
 the whole body may be divided into a number of similar sectors, 
 and the loss of a ray, so long as the middle remains uninjured, 
 does not disturb life, since none of its necessary component 
 parts are wanting. 
 
 In the longitudinal type, which obtains in the Vibriones, Fi- 
 laria, in Gordius*, in the Naida, and in the whole Articulate 
 series, the contrast of ingestion and egestion is relegated to the 
 two extremities of the animal, and thus gives a character to the 
 whole organization; the mouth and the anus are at the two 
 ends, and in general the sexual organs also, yet at times these 
 have their apertures more anteriorly. This is more frequently 
 the case with the female organs, which are not merely egestive, 
 but are also ingestive, than with the male organs. When the 
 organs of both sexes are removed from the posterior extremity, 
 the aperture of the female organs generally is placed more for- 
 ward than that of the male organs. It is thus in the Myriapoda 
 and the great family of Crustacea ; the Leech and the Earth- 
 worm form a rare exception. With the fixed position of the 
 anterior extremity, as the ingestive pole, the organs of the senses 
 as instruments for the receptivity of the nervous system early 
 attain a considerable grade of development. 
 
 So long as the type remains unchanged, the intestinal canal 
 passes straight through the body. It is the same with the vas- 
 cular and nervous systems. Every organic movement then has 
 this principal direction, only subordinate branches pass off 
 laterally; especially when the principal character is repeated 
 along the whole length, as in a galvanic battery, so that every 
 separate segment possesses its own anterior and posterior ex- 
 tremity, together with its portion of the essential constituents of 
 the organism. 
 
 Thence the disposition to break up into many portions in the 
 direction of the length of the body. In the true Insects pos- 
 sessing metamorphosis, these articulations are united again into 
 three principal sections, in the first of w ? hich the nervous, in the 
 second the motor, and in the third the digestive life predomi- 
 
 * If these animals, or some of them, are not perhaps in accordance with the 
 previous note, to be brought under one type with the Holothuriadae. 
 
K. K. VON BAER. PHILOSOPHICAL FRAGMENTS. 199 
 
 nates, although in each of the three segments none of these is 
 wholly absent. 
 
 Together with the principal contrast of anterior and posterior, 
 a slighter one of upper and lower is to be recognized in the 
 higher stages of development. A distinction into right and left 
 sides is only exceptionally present, and as a rule is absent. A 
 perpendicular plane therefore divides the body into two equal 
 halves, whence this organization may be called symmetrical. 
 Every single organ lies in this middle plane, so long as the 
 shortening of the whole body does not drive the less shortened 
 intestine out of the median plane*; and every organ which lies 
 in the median plane is single, while that which lies external to 
 it is double. In the median plane, however, we must recognize 
 a difference of above and below ; the animal organs are concen- 
 trated below, the plastic ones above, if we regard only the in- 
 ternal structure. The trunks of the animal organs also lie below, 
 and they form here a kind of axis, from which the whole organi- 
 zation proceeds on both sides upwards, a relation which is ren- 
 dered obvious by the mode of development (compare Coroll. 4). 
 
 The sensible and the irritable functions are especially deve- 
 loped in this series of animals; their movements are lively, and 
 are the more distinctly directed forwards the more the body is 
 drawn out longitudinally. When the body is shortened, as in 
 the Spiders and Crabs, so much the less determinate is the 
 direction of their movements ; the plastic organs are less deve- 
 loped, the glands are particularly rare, and are generally re- 
 placed by simple tubes. 
 
 I believe that a third type is recognizable in the Mollusca ; 
 and as belonging to its lower grades of development I enume- 
 rate the Rotifera and such Infusoria as are coiled, or at least 
 are neither symmetrical nor peripheral. This type may be called 
 the massive type, for neither length nor surface predominates, 
 but the whole body and all its parts are formed in more rounded 
 masses, which are either solid or hollow. 
 
 As the principal antithesis of animal organization, that of in- 
 gestion and of egestion, is manifested neither by the two opposite 
 
 * In fact, it appears that in Insects which possess metamorphosis, the in- 
 testine is moved out of the median plane, sometimes only in the last stage of 
 metamorphosis, sometimes even in the larval condition 
 
200 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 ends of the body nor by the centre and periphery, it is almost 
 always wanting in symmetry ; the egestive pole lies almost 
 always to the right of the ingestive pole. The opposite relation 
 is so rare, that it has been called inverted. On the other hand, 
 the egestive pole is sometimes very near the ingestive one, 
 sometimes is removed far from it, so that it approximates the 
 posterior end of the body. Since the digestive track is always 
 determined by these two poles, it is more or less curved. In its 
 simplest form the track is simply looped, as in Plumatella. 
 When the alimentary canal elongates, it rolls up spirally in the 
 middle, and the spiral apparently follows determinate laws. The 
 commencement of the intestinal canal thus appears always to lie 
 under the portions which follow. 
 
 The main current of the blood follows a curve which does not 
 lie in the middle line of the animal. If the spiral of the intestine 
 be wound in one plane, a certain symmetry is so produced, as in 
 the discoidal univalves and the equivalve bivalves; but this 
 symmetry is only very unimportant, and it might be called 
 almost accidental, since it is often wanting in nearly allied 
 animals. 
 
 The nervous system is composed of scattered ganglia, which 
 are united by filaments into a network. The larger ones are 
 collected round the pharynx. The psychical apparatus is very 
 little developed, and the organs of sense are late in arising. 
 Motion is very slow and weak. From the absence of articula- 
 tion, the muscles are interwoven in all directions, and operate 
 upon every point by single bundles ; thence arise contractions 
 in all directions. Since, in accordance with the massive arche- 
 type, the secretory organs, which in other archetypes appear as 
 tubes, coil up in this, the glands are abundant and large. The 
 plastic organs in general are those which are earliest and most 
 completely developed ; and thence this archetype might also be 
 called the plastic archetype. Since it possesses neither lateral 
 nor peripheral equivalency, the body can be divided into similar 
 segments neither in one nor in many planes. Neither can any 
 straight axis be demonstrated in it round which the organization 
 is distributed ; it is rather determined by manifold curves. 
 
 In the Vertebrata we find a fourth archetype. It is, however, 
 in a manner constructed out of the preceding archetypes. We 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 201 
 
 can distinguish, that is, a plastic and an animal part of the body, 
 which react mutually upon one another's form, but each of which 
 is modelled upon a different archetype. In the animal part, the 
 existence of articulation calls to mind the second archetype ; 
 ingestion and egestion are similarly referred to the two ends. 
 But there is an essential difference ; the animal part of the ver- 
 tebrate animal, namely, is not merely double on each side of a 
 longitudinal axis, but also from above downwards, and in such 
 a manner that the two inferior lateral developments enclose the 
 plastic organs, while the two superior include central organs of 
 animal life (spinal cord and brain), which are wanting in the 
 Invertebrata. The solid bony skeleton represents this type most 
 completely; from a median axis, the trunk of the vertebral 
 column, arches pass upwards, which unite in a superior crest, 
 and other arches downwards, which more or less unite into aii 
 inferior crest. Corresponding with this, we have four series of 
 insertions of nerves into the spinal cord, which again contains 
 four principal cords, and a four-lobed internal gray mass. In 
 the same way, the muscles of the trunk form four principal 
 masses, as we see most distinctly in Fishes. The animal part, 
 therefore, is doubly symmetrical in its construction. 
 
 Here, as in the essay in the ( Nova Ada 9 already cited, I will 
 not decide whether, in the course of the further development of 
 the Vertebrata, the anterior part of the animal region approxi- 
 mates more and more to the radiate archetype ; I would only 
 suggest, that the brain accumulates more and more round the 
 third ventricle, and that the cerebral vessels also pass into the 
 brain from a ring, which becomes continually more and more 
 rounded, although this ring is fed by four vascular trunks, 
 as representing a relation, such, that from a type in which 
 the parts were originally arranged in fours, a radiate one is 
 developed. 
 
 However, it appears to me to be more readily demonstrable, 
 that the type of the Mollusk predominates over the plastic part 
 of the body, although everywhere under the influence of the 
 animal part, by which the type is sometimes more, sometimes 
 less obscured. 
 
 The plastic nervous system, as well as the peculiarity of the 
 plastic muscular system, calls to mind the molluscous type. 
 
202 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 But the chief matter is to demonstrate that the most essential 
 peculiarity, the direction of the vital organic current, has a pre- 
 vailing tendency towards the right side. If now this lateral con- 
 trast does not manifest itself in the ingestive and egestive aper- 
 tures, the reason perhaps lies in this, that the plastic body is 
 surrounded by the animal body ; and, therefore, when the former 
 comes to the surface, it is wholly subjected to the type of the 
 latter. The mouth and the anus therefore lie in the median 
 plane of the whole body*. 
 
 If we turn to the internal organs, we must not forget that, 
 
 1 . Almost all organic progression is followed by a retrogression. 
 Were this not the case, a few beats of the heart would drive all 
 the blood out of the body. The question here then is only to 
 state what is the direction of that movement which is the deter- 
 mining one. 
 
 2. That in other cases also the motion can be withdrawn from 
 the direction which originally belongs to it if it possesses a 
 starting-point, which according to the laws of the organization 
 is also the termination of another more powerful organization. 
 
 3. That by the symmetrical influence of the animal part, a 
 current is set up in the median plane of the plastic part. Then 
 if we find a movement at times external to this plane also, but 
 always taking the same direction, we should consider this as the 
 original one. 
 
 These remarks will be rendered more clear by the application 
 which will immediately be made of them. 
 
 If, in the first place, we consider the movement of the blood, 
 we find that in Fishes its principal stream proceeds in the me- 
 dian plane out of the heart, without doubt only on account of 
 the predominance of the animal part, in which respect we must 
 refer to a remark to be made concerning the respiratory apparatus. 
 
 And yet it would seem even here as if the blood desired to go 
 towards the right side, for the ventricle of Fishes appears in 
 general to be more extended towards the left side, and the auricle 
 also lies towards the left. The direction which the blood thence 
 receives is somewhat to the right, but the symmetrical structure 
 of the gills keeps it back in the median plane. In all animals 
 
 * Yet in the larva of the Frog, the anus lies in fact on the right side of the 
 median plane of the tail. 
 
K. E. VON BAEB. PHILOSOPHICAL FRAGMENTS. 203 
 
 with lungs, however, the stream of the blood passes obviously 
 more to the right than to the left side ; so that for the nutrition 
 of the left half of the head, the blood must often come over from 
 the right side. This blood then has a motion from right to left, 
 which we must regard as a consequence of symmetry in the 
 animal part. It is unquestionably the left ventricle which is the 
 chief agent in propelling the blood, and this always sends the 
 blood to the right side. In the Lizards, Snakes, and Chelonia, 
 all the blood which is intended for the nutrition of the anterior 
 half of the body passes first in a single stream to the right 
 side, and then becomes distributed ; the blood for the anterior 
 extremity now passes forwards almost symmetrically in two 
 streams ; the blood intended for the posterior extremity in Birds 
 continues its course without dividing to the right side, and by 
 degrees, as the influence of symmetry gradually weakens that of 
 the motor power, it turns leftward again, so as to reach the me- 
 dian line. In the Amphibia above mentioned, the power of 
 symmetry sooner becomes manifest; the current of blood for 
 the posterior half of the body is also divided at the first, but 
 much more blood passes to the right than to the left side, and 
 the latter becomes sooner divided, as if it were propelled with 
 less force. In the Batrachia, the distribution is from the first 
 tolerably symmetrical. In Mammalia, the aorta descends in- 
 deed upon the left side of the vertebral column ; but if we con- 
 sider that the position of the aorta is always determined by a 
 large and common trunk for the anterior and posterior arteries, 
 that this common trunk is always directed towards the right 
 side, and first becomes turned to the left after it has given off 
 the arteries of the right anterior half of the body, or gives them 
 off as it turns ; the passage to the left side may be regarded as 
 arising from the influence of symmetry, for the arch which the 
 aorta forms is the wider the shorter the neck. In other words, 
 the aorta passes the more to the left side, the nearer it stands to 
 the head whose influence tends towards symmetry. In the 
 long-necked Mammals, where from the common trunk upon the 
 right side, that for the carotid artery and subclavian arteries (the 
 anterior aorta) passes, the branch which passes backwards turns 
 so suddenly that it can hardly be said that it passes to the left. 
 Such considerations may perhaps explain why it is that the 
 
204 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 Mammalia differ from other pulmonated Vertebrata in the posi- 
 tion of their descending aorta. I believe that this difference 
 depends upon the greater need of blood demanded by their 
 brain. Let us consider, in some indifferent vertebrate animal, 
 the stream of blood passing from the left ventricle to the right 
 side. If the brain have a great demand for blood, this common 
 stream of blood, besides its direction to the right side, will take 
 at the same time a more forward direction than in animals with 
 a small brain and head. In the latter, therefore, the blood which 
 is intended for the posterior half of the body, after giving off the 
 blood to the anterior half, is by the influence of the current im- 
 mediately bent backwards, though continued for a little to the 
 right side. If, however, the current forward be more powerful, 
 the backward stream can only gradually overcome it, and the 
 aorta needs to pass further forwards, and to the right side ; or if 
 the influence of symmetry will not allow of this, it must bend 
 round to the left in order to pass backwards. That the blood 
 in the Mammalia actually has a more powerful current forwards, 
 is indicated by the greater length of the common trunk ; and the 
 fact that among the Mammalia again, the longer this common 
 trunk is the wider the arch, is perhaps a confirmation of what 
 has been said. In this way we may conceive the origin of the 
 difference in a formless mass. How it is developed out of the 
 symmetrical branchial apparatus of the Mammalia remains to be 
 decided by future investigations. 
 
 Even when the heart lies in the median plane of the body, the 
 origin of the aorta, as soon as there are two ventricles, is always 
 so disposed that the impulse which is given to the blood by the 
 left ventricle passes to the right side. When the point of the heart 
 turns to the left, this relation is still more marked (see figure on 
 p. 238, arrow 1). A direction of the heart towards the right 
 side never appears to be normal. I believed that I had at times 
 observed it, but I persuaded myself that this position arose only 
 from a slipping about in the body of the animal inverted for the 
 purpose of examination. We may therefore be permitted to 
 place the heart in such a manner in our diagram as it is disposed 
 in Man and some other animals*. I choose the oblique position 
 
 * It would seem that the symmetrical position of the heart is too generally 
 ascribed to quadrupeds. It appears to me to occur only in animals with a 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 205 
 
 of the heart, in order to show by it how the strong development 
 of the currents in a predominant organ may produce an opposite 
 current in a dependent part of the same system. In most ani- 
 mals the pulmonary blood flows straight backwards into the left 
 heart; where, however, this is placed in such a manner that 
 it propels decidedly towards the right side, the current of pul- 
 monary blood takes a slight direction to the left side (!'). 
 
 So much for the direction of the arterial current. That the 
 venous current is also directed towards the right side is much 
 more obvious. The blood from the left side of the anterior half 
 of the body passes very markedly towards the right side. We 
 may therefore at once indicate the course of the venous blood 
 from the anterior part of the body by the arrow 2. That the 
 blood from the posterior part of the body also moves towards 
 the right side is shown by the deviation of the posterior vena 
 cava to the right the further forwards it passes, as well as by the 
 conformation of the intercostal trunks ; the arrow 3 represents 
 this current. It is still clearer in the portal system (4). If we 
 cast a glimpse over the whole series of animals, we find the 
 respiratory system sometimes connected with the ingestive, some- 
 times with the egestive end of the body, sometimes disposed 
 longitudinally between the two extremes. This variety of posi- 
 tion appears to be possible to the respiratory apparatus, because 
 its function is as well excretory as ingestive. One is tempted 
 to suppose that in those forms of animals in which the respi- 
 ratory apparatus occupies the anterior extremity, it acts more 
 ingestively; while, on the other hand, it is more egestive in 
 those in which it opens together with or near the intestine, as 
 in the Holothuriadae, most Mollusks, and some larva? of Insects. 
 If we extend this supposition to the changes undergone by the 
 blood itself, it must still remain hypothetical, for at present in 
 very few animals only can we determine whether the blood loses 
 or gains substance during respiration. It appears to me, however, 
 to be very clear, that in those respiratory apparatuses which are 
 placed anteriorly, the ingestive movement at least is the deter- 
 
 compressed thorax. In animals with a flattened thorax, the heart lies more or 
 less obliquely, and in the embryonic condition sometimes more so than in the 
 adult. Thus, recently, in many embryo Hedgehogs, I found the heart directed 
 very markedly towards the left side, while it was much less so in the mother. 
 
206 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 mining one, while in those which are situated posteriorly it is 
 the egestive movement. In the Holothuriadae, the Mollusks, 
 the larvae of Insects which inhale air by their hinder extremities, 
 the respiratory organs are emptied by muscular contractions. 
 The refilling is principally a consequence of the cessation of 
 muscular activity ; at least, if an antagonistic muscular action be 
 superadded, it is less than the expelling force. The reverse takes 
 place in the pulmonated animals ; the reception of air is here 
 more active, its expulsion is more passive. The inhalant passage 
 will therefore determine the position of the apparatus, not the 
 retrogressive passage of the exhaled air. Now, though we find 
 the lung double, yet in all animals the right lung is larger, and 
 in the true Ophidia it is this alone which is developed, a trace 
 only remaining of the left. To this may be added, that in some 
 Cetacea, as in the genus Physeter, the right nostril is dwarfed. 
 Indeed it may obtain even more generally that the right nasal 
 aperture is smaller than the left, as we see for example in Som- 
 mering's description of the skull of the fossil Hyaena. We may 
 then shortly indicate the course of the air in the respiration of the 
 Vertebrata by the arrow (5) in our figure (p. 238). In the gills 
 of Fishes it must be admitted that no such lateral difference is 
 apparent; but the gills are so immediately connected with the 
 animal part of the body, as the transitory gill-arches of the pul- 
 monate animals testify, that the asymmetry of the plastic body 
 cannot develope itself in them. 
 
 When an apparatus like the digestive passes from one pole to 
 the other through the whole length of the plastic body, it cer- 
 tainly cannot send its contents always to the right side. It is 
 only to be expected, that in those sections in which the motor 
 powers are most strongly manifested, which are therefore those 
 which determine the position of the whole, the course of the cur- 
 rent will be in this direction. Now we find in all Vertebrata, so 
 far as I know, that the stomach lies to the left and the pylorus 
 to its right side, as well as the commencement of the duodenum, 
 turning to the right whether it pass at the same time forwards 
 or not. The stomach therefore propels its contents towards the 
 right side. The same relation is frequent in the muscular rec- 
 tum. Other sections must indeed pass from right to left, but 
 they are the less active. Thus I conceive that if the floor 1 in 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 20? 
 
 Mammals passes to the left in order to reach the stomach, this 
 opposed direction is only produced by the influence of the sto- 
 mach, which, in order to propel to the right, lies towards the 
 left. It is also only the posterior part of the oesophagus which 
 is overruled by the stomach ; for when the bony skeleton of the 
 neck is so much bent that the oesophagus passes away from its 
 under surface, the oesophagus always, if 1 err not, lies on its 
 right side with the exception of its posterior extremity. I found 
 its position thus in Birds, in Chelonia, in the Camel, in the 
 Sloth, and probably in many other Mammals the same holds 
 good. When in Birds a special crop is developed, this also is 
 placed upon the right side. The course of the motion from the 
 pharynx, therefore, which is produced by the powerful constrict- 
 ors, is in general towards the right side. Compare arrow 6*. 
 
 The course of the bile generally is from the right to the left ; 
 but this reversed direction may be regarded as dependent upon 
 the position of the liver, which is thrust to the right side in con- 
 sequence of the predominant current of the portal blood. In fact, 
 in the course of embryonic development, the liver passes to the 
 right side in proportion to the separation of the portal system 
 from the other vessels. 
 
 As respects the sexual organs, they are as a rule tolerably 
 symmetrical, in consequence of their intimate connexion with 
 the animal body, which is rendered evident not only by their 
 position in the adult, but especially by the history of develop- 
 ment. Where, however, symmetry is less prominent, as for 
 example in the hen-bird only, the left oviduct is developed, and 
 the egg therefore is moved from the left towards the right side. 
 The direction of this movement is exhibited by the arrow 8. 
 Hitherto all the arrows which have been drawn have their points 
 directed towards the right side. The urinary passages only ap- 
 pear not to harmonize with this law. When the kidneys upon 
 the two sides do not agree, as in the Ophidia, it is that of the 
 right side, which is longer and placed more anteriorly. The 
 
 * That the passage from right to left again is submitted to a determinate 
 standard, that therefore a definite form of spiral canals might be demonstrated 
 when the current cannot be continued to the right side, scarcely admits of 
 doubt. Yet here the perturbations are so frequent, and the discovery of the 
 type is so difficult, that this attempt would carry us too far. Besides, I con- 
 sider *Jhe current to the right to be that which is predominant and common to 
 all systems, and for our present purpose it is sufficient. 
 
208 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 course of the urine would then seem especially to be towards 
 the left. If the principal activity of the kidneys should consist 
 in attracting venous blood, merely allowing the urine to transude, 
 they would come under the general law*. 
 
 Enough of the demonstration that the organic current in the 
 plastic part of the Vertebrata has a direction especially towards 
 the right side, in order to show that the arrangements of the 
 molluscous type prevail in this half of the vertebrate animal. 
 
 We have now considered the four archetypes, and it will be 
 sufficient for our purpose to remark shortly, that these arche- 
 types become modified in the subordinate forms, like the varia- 
 tions of one theme. Thus the segments of the Articulate series 
 sometimes more resemble one another, as if they were strung upon 
 a thread, sometimes they are collected round a central point. 
 In this manner variations of the archetypes are formed, which 
 may be conceived to be arranged round them, and some of which 
 are more nearly approximated to them, representing more purely 
 the character of the archetype, while others are further removed. 
 These subordinate types, combined with a determinate degree of 
 development, yield what we call the classes of animals. In these 
 it is sometimes one, sometimes another vital condition which is 
 more developed ; or more justly, the development of life in this 
 or that direction produces the variations of the archetypes, just 
 as these are themselves essentially different in the vital pheno- 
 mena which they manifest. Thus among the Vertebrata it is 
 plainly the Birds, in which the relation to the air is predominant. 
 It penetrates their whole body, and for it the anterior motor 
 organs are constructed. So with the true winged Insects among 
 the Articulata. The classes of animals again are divisible into 
 smaller variations, which we call families, in which not only the 
 archetype but the type of the class is exhibited, together with 
 peculiar modifications which constitute the character of the 
 family. Smaller modifications in this family character yield the 
 genera. And so it goes on down to the species and subspecies. 
 
 * The preponderance of the right kidney is not universal even in the 
 Snakes. At times their length is balanced by the greater thickness of the 
 left kidney, as I observe in Vipera Berus. In Tortrix Scytale, however, the 
 preponderance of the right kidney is, I find, according to Meckel and Finke, 
 evident. It is remarkable that the urinary system is the only one which is 
 aberrant in the peripheral type also. 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 209 
 
 If it be true that all the larger and smaller groups of animals 
 depend upon a double relation, that of higher or lower develop- 
 ment, and that of the variation of the archetypes into differences 
 of smaller degree, and these again further, then the conception 
 of a uniserial progressive development of the whole animal 
 kingdom is incorrect. 
 
 4. Application of this View to the History of Individual 
 Development. 
 
 Let us now apply the survey of the permanent relations of 
 form among the various perfect animals to the history of the 
 development of the individual ! 
 
 Before all things it is clear, that the conditions which we have 
 termed the higher and lower development of the animal, coincide 
 perfectly with that histological and morphological differentiation 
 which gradually arises in the course of the development of the 
 individual (comp. Schol. III. c. d.). In this respect the agree- 
 ment is striking. The fundamental mass of which the embryo 
 consists agrees with the mass of the body of the simplest ani- 
 mals. In both the form is but little defined; the parts are less 
 contrasted, and the histological differentiation remains even 
 behind the morphological. If we cast a glance over the lower 
 animals, remark in some more internal development than in 
 others, and then arrange them in a series according to this deve- 
 lopment, or conceive them to be developed out of one another; 
 it necessarily follows that we should trace an agreement in the 
 fact of this very progressive differentiation between the one 
 actual historical succession and the other imagined genetic 
 series ; and in this manner a multitude of coincidences may be 
 demonstrated between the embryo of the higher and the per- 
 manent forms of the lower animals. 
 
 It by no means follows from this, however, that every embryo 
 of a higher animal gradually passes through the forms of the 
 lower animals. On the cortrary, the type of every animal ap- 
 pears to be fixed in the embryo from the very first, and to regu- 
 late the whole course of development. 
 
 All that we have stated with regard to the development of the 
 Chick is only a long commentary upon this proposition. The 
 chorda dorsalis is the first part which becomes differentiated. 
 
 SCIEN. MEM. Nat. Hist. VOL. I. PART III. 14 
 
210 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 From this the dorsal plates elevate themselves, and the abdo- 
 minal plates soon arise, and the spinal cord becomes separated. 
 All these formative processes take place very early ; and it is 
 obvious that henceforward there can be no question of any 
 agreement with an invertebrate animal ; that, on the other hand, 
 those conditions which essentially constitute the vertebrate 
 animal are the first to arise ; the commencement of their deve- 
 lopment is however very similar in all classes of the Vertebrata. 
 We may therefore say, not merely of Birds, but more generally, 
 The embryo of the vertebrate animal is from the very first a 
 vertebrate animal, and at no time agrees with an invertebrate 
 animal. A permanent animal form, however, which exhibits 
 the vertebrate type, and yet possesses so slight a histological 
 and morphological differentiation as the embryos of the Verte- 
 brata, is unknown. Therefore, the embryos of the Vertebrata 
 pass in the course of their development through no (known) per- 
 manent forms of animals whatsoever. 
 
 Can, however, no law be discovered to regulate the develop- 
 ment of the individual as the possessor of a special organic form ? 
 I believe there can, and I shall endeavour to educe it in the 
 course of the following remarks. The embryos of Mammalia, 
 of Birds, Lizards and Snakes, probably also of Chelonia, are in 
 their earliest states exceedingly like one another, both as a whole 
 and in the mode of development of their parts ; so much so, in 
 fact, that we can often distinguish the embryos only by their 
 size. In my possession are two little embryos in spirit, whose 
 names I have omitted to attach, and at present I am quite unable 
 to say to what class they belong. They may be Lizards, or 
 small Birds, or very young Mammalia, so complete is the simi- 
 larity in the mode of formation of the head and trunk in these 
 animals. The extremities, however, are still absent in these 
 embryos. But even if they existed in the earliest stage of their 
 development, we should learn nothing ; for the feet of Lizards 
 and Mammals, the wings and feet of Birds, no less than the 
 hands and feet of Man, all arise from the same fundamental 
 form. The further, therefore, we recede in tracing the formation 
 of the Vertebrata, the more similar we find the embryos in their 
 totality and in their separate parts. At first those characters 
 gradually present themselves which indicate the greater, and 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 211 
 
 subsequently those which mark the smaller, divisions of the 
 Vertebrata. 
 
 Thus the more special type is developed from the more general. 
 Every step in the development of the Chick testifies to this. In 
 the beginning, when the dorsal folds have closed, it is a verte- 
 brate animal, and nothing more. As it raises itself from the 
 yelk, as the gill-plates coalesce and the allantois grows forth, it 
 shows itself to be a vertebrate animal, which cannot live freely 
 in water. Subsequently the two caeca grow forth, a distinction 
 appears between the pairs of extremities, and the beak is deve- 
 loped ; the lungs pass upwards ; the rudiments of the air-sacs 
 are recognizable, and there can be no doubt as to its being a 
 Bird. While the ornithic characters become more and more 
 marked, in consequence of the further development of the wings 
 and air-sacs, of the coalescence of the tarsal cartilages, &c., the 
 web of the feet disappears, and we recognize a land Bird. The 
 beak, the feet, pass from the general into a special form ; the 
 crop is developed, the stomach has already divided into two cavi- 
 ties, and the scale of the nostrils appears. The Bird takes on the 
 character of a Gallinaceous bird, and finally of a domestic fowl. 
 
 It is an immediate consequence, in fact it is merely a changed 
 form of expression of what has been said above, that the more 
 different two animal forms are, so much the further back must 
 their development be traced, to find them similar*. To demon- 
 strate that this is true, not merely for the Vertebrata, we will 
 select a few examples from the lower animals. The difference 
 between the Macrurous and Brachyurous Crustacea is not 
 very great. Now the river Crayfish has at the middle of its 
 embryonic life a tail tolerably short in relation to its broad tho- 
 racic segments, and it can be hardly distinguished from a Bra- 
 chyurous Crustacean, since, according to Cavolini's representa- 
 tion, these have in their embryonic condition tolerably long tails. 
 The further we trace them back, the more similar do we find the 
 jaws in Crustacea to the feet; in truth, they are at first the 
 anterior feet, and nothing else. We have therefore not only an 
 approximation to the fundamental type (agreement of allied or- 
 gans), but also a similarity with the Stomapoda, Amphipoda 
 
 * This remark does not invalidate what has been said in the First Scholium 
 as to the indefiniteness of the same form in its earliest condition. 
 
 14* 
 
212 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 and Isopoda, which in their perfect condition are far more differ- 
 ent from the Decapoda than these from one another. To this it 
 must be added, that, according to Rathke, the heart in the De- 
 capoda (IsiSy Bd. xvii. p. 1098) is at first fusiform, and doubtless 
 there are many more points of agreement as yet undiscovered. 
 
 At a still earlier period, when the feet sprout forth at the sides 
 like little knobs, and no gills are as yet visible, we cannot mis- 
 take the similarity to true Insects in the larval state. A Butter- 
 fly and an Ichneumon may be readily mistaken for one another 
 even as full-grown larvae. Such larvae have indeed been com- 
 pared with Vermes, but it must be confessed that the essential 
 differences are still very great. The latter have red blood and 
 no tracheae. In the former the reverse obtains. In fact, the 
 full-grown caterpillars are much more similar to the Myriapoda, 
 and only at a very early period, when no tracheae are developed 
 (these being probably formed by histological differentiation), is 
 there any approximation to the embryo of the Leech when it 
 has not yet developed red blood. 
 
 These remarks lead us to inquire, whether by going further 
 and further back, we may not eventually attain a stage in which 
 the embryos of the Vertebrata agree with those of the Inverte- 
 brata. In a future essay, in which the differences in the schemes 
 of development in the principal types of animals will be treated 
 of, I shall endeavour to show that the Articulate series also com- 
 mences its development by a primitive streak. For this short 
 period, therefore, there would be an agreement between them 
 and the Vertebrata. In the condition of the actual germ, how- 
 ever, it is probable that all embryos which are developed from 
 true ova agree. This is a strong reason for considering the germ 
 as the animal itself (Schol. II.). When in the germ of the Bird 
 the primitive streak is developed, we are indeed inclined to say, 
 Now commences the embryo. But in reality this is only the 
 instant in which the vertebrate type appears in the germ ; for the 
 primitive streak is nowise the whole embryo, inasmuch as the 
 parts which are metamorphosed into the abdominal plates evi- 
 dently lie beside it in the germ. It is only that part of the 
 germ which first becomes individualized. A so-called germinal 
 disc is however distinctly visible in the ova of the Articulata. It 
 is almost certainly present in the Mollusca, for the ovum of 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 213 
 
 Gasteropods has an unequal coloration upon its surface. Be- 
 sides I have seen clearly the germinal layer and the germinal 
 vesicle, the predecessors of the germ. It therefore seems to me 
 very probable that all true ova have a distinct germ. 
 
 The further back we trace development, so much the more 
 agreement do we find among the most widely different animals, 
 and thus we are led to the question, Are not all animals essen- 
 tially similar at the commencement of their development have 
 they not all a common primary form ? We have just remarked, 
 that a distinct germinal disc probably exists in all true ova ; so 
 far as we are acquainted with the development of germ-granules 
 (Keim-korner), it seems to be wanting in them. They appear 
 to be originally solid; however it may be, that on their first 
 separation from their parent, they have an internal cavity like 
 the central cavity of the yelk, which only escapes microscopic 
 observation on account of the thickness of the often somewhat 
 opake wall. Supposing, however, they are at first solid, and 
 eventually become hollow, as seemed to me to be the case with 
 the germ-granules of the Cercariae and Bucephali*, yet we 
 perceive that the first act of their vital activity is to acquire a 
 cavity, whereby they become thick-walled, hollow vesicles. The 
 germ in the egg is also, according to Schol. II. c, to be regarded 
 as a vesicle, which in the Bird's egg only gradually surrounds 
 the yelk, but from the very first is completed as an investment 
 by the vitellary membrane ; in the Frog's egg it has the vesicular 
 form before the type of the Vertebrata appears, and in the Mam- 
 malian from the very first it seems to surround the small mass 
 of the yelkf. Since, however, the germ is the rudimentary 
 animal itself, it may be said, not without reason, that the simple 
 vesicle is the common fundamental form from which all animals 
 are developed, not only ideally, but actually and historically. 
 The germ-granule passes into this primitive form of the inde- 
 pendent animal immediately by its own power ; the egg, how- 
 ever, only after its feminine nature has been destroyed by fecun- 
 dation (compare the Coroll. to Schol. I.). After this influence, 
 the differentiation of germ and yelk, or of body and nutritive 
 substance, arises. The excavation of the germ-granule is nothing 
 
 * Nova Acta Acad. Nat. Cur. vol. xiii. T. 2. p. 658. 
 
 f Heusinger's Zeitschrifl fur organische Physik, Bd. ii. p. 173. 
 
214 K. E. VON BAEB. PHILOSOPHICAL FRAGMENTS. 
 
 else. In the egg, however, there is at first a solid nutritive 
 matter (the yelk), and a fluid in the central cavity ; yet the solid 
 nutritive matter soon becomes fluid. 
 
 We remarked above, that to find a correspondence between 
 two animal forms, we must go back in development the further 
 the more different these two forms are ; and we deduce thence, 
 as the law of individual development, 
 
 1. That the more general characters of a large group of ani- 
 mals appear earlier in their embryos than the more special cha- 
 racters. 
 
 With this it agrees perfectly, that the vesicle should be the 
 primitive form ; for what can be a more general character of all 
 animals than the contrast of an internal and an external surface ? 
 
 2. From the most general forms the less general are developed, 
 and so on, until finally the most special arises. 
 
 This has been rendered manifest above by examples from the 
 Vertebrata, especially of Birds, and also from the Articulata. 
 We bring it forward again here only to append, as its immediate 
 consequences, the following propositions concerning the object 
 of investigation : 
 
 3. Every embryo of a given animal form, instead of passing 
 through the other forms, rather becomes separated from them. 
 
 4. Fundamentally, therefore, the embryo of a higher form 
 never resembles any other form, but only its embryo. 
 
 It is only because the least developed forms of animals are 
 but little removed from the embryonic condition, that they retain 
 a certain similarity to the embryos of higher forms of animals. 
 
 This resemblance, however, if our view be correct, is nowise 
 the determining condition of the course of development of the 
 higher animals, but only a consequence of the organization of 
 the lower forms. 
 
 The development of the embryo with regard to the type of 
 organization, is as if it passed through the animal kingdom after 
 the manner of the so-called methode analytique of the French 
 systematists, continually separating itself from its allies, and at 
 the same time passing from a lower to a higher stage of develop- 
 ment. We represent this relation by the annexed Table : 
 
, :R . PHILOSOPHICAL FRAGMENTS. 215 
 
 si ;ti9mrprLi reuiiuc aqx 
 
216 K.E.VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 In detail it holds good as little as any other representation of 
 organic relations upon a surface. Thus the single features ad- 
 duced must pass for the whole characters, e. g. the formation of 
 wings and air-sacs for the whole character of Birds. The expo- 
 sition, again, can only be very imperfect, since for most animals 
 the investigation has hardly been commenced. 
 
 This scheme is only meant to bring clearly before the mind, 
 how the first decisive distinction is whether the first rudiment 
 is a true egg or a germ-granule ; how, in the germs of ova, all 
 animals are at first alike (see above, e) ; how then the principal 
 type becomes defined (which is called, origin of the embryo) ; 
 whereby it remains undecided \vhether any radiate animal is 
 developed from a true egg. If now the type of the vertebrate 
 animal appears, the embryo is at first nothing but one of the 
 Vertebrata without any particular characteristics. Chorda dor- 
 salis, dorsal and abdominal tubes, gill-clefts, gill-vessels, and a 
 heart with a single cavity, are formed in all. Then commences 
 a differentiation. In a few, gill-laminas and no allantois are de- 
 veloped ; in others, on the other hand, the gill-clefts coalesce, 
 and an allantois buds forth. The former are aquatic animals, 
 though not all permanently so : the others lead an aerial exist- 
 ence. The latter all acquire lungs. Let us follow out the 
 former series first however. The embryos for a long time retain 
 a great similarity ; they push out long tails and scull about with 
 them in the water. On the other hand, their extremities are 
 developed very feebly and late, in relation to those of other em- 
 bryos. They either never acquire true lungs, and so become 
 fish, or else true lungs are formed. Among the latter the lungs 
 are either feebly developed, in which case the gills are permanent 
 and the animals become Sirenidae ; or the lungs are better 
 formed, and the gills either remain free until they cease to act 
 (Salamanders), or they become covered over, the tail disappears, 
 and with it all resemblance to a fish (tail-less Batrachia). In 
 the second series of the Vertebrata, which never has external 
 gills, the most essential distinction is perhaps this, that in 
 some a simple umbilicus is formed (Reptiles and Birds), in 
 others this umbilicus is prolonged into a cord, after, as it seems, 
 being altogether more rapidly formed (Schol. II. b.}. 
 
 In what manner Birds become separated from the Amphibia 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 21? 
 
 has already been shown. Probably a difference also arises very 
 soon in the vascular system, whose metamorphoses in the Am- 
 phibia, however, are not yet known. While the gill-clefts in 
 the Lizards are still open, the heart has just the same appearance 
 as in Birds at the same period. Now just as in the Bird the 
 special characters of the family and of the genus arise, so is it in 
 the Mammalia. The Dog and the Pig are at first very much 
 alike, and have short human faces. Still longer does the resem- 
 blance persist between the Pig and the Ruminant, whose lateral 
 toes are at first almost as long as the two median ones. For the 
 rest we are by no means sufficiently acquainted with the em- 
 bryos of the Mammalia to state how and at what periods they 
 become distinguishable from one another. We are best ac- 
 quainted with the differences in the form and structure of the 
 ova. Since these are very manifold in their form and in their 
 relation to the parent, I have ventured, in order not to leave the 
 Mammalia out of the Scheme, to divide them according to their 
 ova. The embryos, in fact, may be distinguished into those 
 which are born early and those which come into the world in a 
 fully developed condition. Among the former the ova of the 
 Monotremata are probably born undisturbed. In the Marsu- 
 pialia the embryo has burst its membranes. The ova, which 
 are retained longer, may be reduced to three principal divisions. 
 In the first I place ova, in which the yelk-sac continues to grow 
 for a long time. They yield Mammals with narrow hook-like 
 nails (claws). In some the allantois is early arrested in its 
 growth, and the placenta is limited to one spot, or two-lobed* 
 (Rodentia). In others the allantois is developed to a moderate 
 extent (Insectivora) : in all others it grows over the whole am- 
 nion transversely, and the placenta is annular (Carnivora). A 
 second division of long-retained ova is formed by those in which 
 the yelk-sac and the allantois are small; the placenta is one- 
 sided, and is, as it would seem, in the opposite position to that of 
 the Rodentia; the amnion and the umbilical cord are here 
 
 * I must for the present follow Cuvier in stating that in the Rodentia the 
 allantois remains very small, since in my earlier investigations I did not pay 
 sufficient attention to this point, and for the last three months I have endeavoured 
 in vain to obtain pregnant Rabits. The allantois is moderately large in the 
 Hedgehog (one of the Insectivora), as I have recently observed. 
 
218 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 largest. These ova produce animals with flat nails and three- 
 lobed cerebral hemispheres*. A third division has a yelk-sac 
 which soon disappears, but an allantois which grows outimmensely 
 at its two extremities. These ova produce ungulated and finned 
 animals ; if the placenta is distributed over the whole ovum, but is 
 collected in particular masses, we have animals with cleft hoofs ; 
 if it is distributed homogeneously, we have other Ungulata and 
 Cetaceaf. Hence the principal differences of the Mammalia are 
 marked very early in the ovum, for according as the allantois is 
 much developed, or otherwise, does the ovum become long or 
 short J. In the former case, the embryo not only acquires a 
 broader horny covering upon its fingers, but also a more com- 
 plex stomach, and, in connexion therewith, long jaws, a flat 
 articulation of the jaw, usually complex teeth, incapability of 
 seizing and climbing, &c. &c. It is the plastic series among the 
 Vertebrata. 
 
 I must advert to an objection against the whole view here set 
 forth, which may be based upon the circumstance that in some 
 cases the embryos of nearly allied animals exhibit considerable 
 differences at an early period. The embryos of the Ophidia, for 
 instance, are very early rolled up, and so may be readily enough 
 distinguished from Lizards. This plainly arises from the ex- 
 cessive length to which in this case the vertebrate type is drawn 
 out. 
 
 Dissection, however, exhibits a great harmony in the internal 
 structure ; and since the posterior extremity of the Lizards also 
 forms a spiral, the difference probably lies merely in this, that 
 the vertebrate type in the Ophidia is more elongated, and it 
 seems, in fact, to be greater than it is, because it presents itself 
 so nakedly. Thus also the larvae of many families of Insects are 
 in their external appearance very different in different families. 
 Much probably depends in this case upon their shorter or longer 
 sojourn in the egg. However, this objection, the only one which 
 
 * It would be very interesting to know the ova of the Lemurs, so as to ascer- 
 tain whether they are very similar to those of the Monkeys or not. 
 
 f According to a letter of Rudolphi's, the chorion of the Dolphin is similar 
 to that of the Horse. According to Bartholin it is a placenta exilis. 
 
 J' Perhaps the difference may be recognized still earlier in the chorion. See 
 Ueber die Gefassverbirtdnng zwischen Mutter und Frucht. Leipzig, 1828, fol. 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 219 
 
 I have been able to discover against the view in question, can 
 have little weight so long as no internal differences in the larvae 
 have been demonstrated. 
 
 For the simple reason, that the embryo never passes from one 
 principal type to another, it is impossible that it can pass suc- 
 cessively through the whole animal kingdom. Our Scheme, 
 however, shows at once that the embryo never passes through 
 the form of any other animal, but only through the condition of 
 indifference between its own form and others ; and the further 
 it proceeds, the smaller are the distinctions of the forms between 
 which the indifference lies. In fact, the Scheme shows that the 
 embryo of a given animal is at first only an indeterminate Ver- 
 tebrate, then an indeterminate Bird, and so forth. Since at the 
 same time it undergoes internal modification, it becomes in the 
 whole course of its development a more and more perfect 
 animal. 
 
 However, it may be objected here, if this be the true law of 
 development, how comes it that so many good reasons could be 
 adduced for that which has been previously in vogue ? This may 
 be explained readily enough. In the first place, the difference 
 is not so great as it looks at first sight ; and in the second, I 
 believe that an assumption was made in the latter view, and it 
 was afterwards forgotten that it had not been demonstrated; 
 but especially, sufficient stress was not laid upon the distinction 
 between type of organization and grade of development. 
 
 Since, in fact, the embryo becomes gradually perfected by 
 progressive histological and morphological differentiation, it 
 must in this respect have the more resemblance to less perfect 
 animals the younger it is. Furthermore, the different forms of 
 animals are sometimes more, sometimes less remote from the 
 principal type. The type itself never exists pure, but only 
 under certain modifications. But it seems absolutely necessary 
 that those forms in which animality is most highly developed 
 should be furthest removed from the fundamental type. In all 
 the fundamental types, in fact, if I have discovered the true ones, 
 there exists a symmetrical (gleichmassige) distribution of the 
 organic elements. If now predominant central organs arise, 
 especially a central part of the nervous system, according to 
 which we must principally measure the extent of perfection, the 
 
220 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 type necessarily becomes considerably modified. The Worms, 
 the Myriapoda, have an evenly annulated body, and are nearer 
 the type than the Butterfly. If then the law be true, that in 
 the course of the development of the individual the principal 
 type appears first, and subsequently its modifications, the young 
 Butterfly must be more similar to the perfect Scolopendra, and 
 even to the perfect Worm, than conversely the young Scolo- 
 pendra, or the young Worm, to the perfect Butterfly. Now if 
 we leave out of sight the peculiarities of the Worm, the red 
 blood, &c., which it attains at a later period, we may readily say 
 that the Butterfly is at first a Worm. The same thing is ob- 
 vious in the Vertebrata. Fishes are less distant from the fun- 
 damental type than Mammalia, and especially than Man with 
 his great brain. It is therefore very natural that the Mam- 
 malian embryo should be more similar to the Fish than the em- 
 bryo of the Fish to the Mammalian. Now if one sees nothing 
 in the Fish but an imperfectly developed Vertebrate (and that 
 is the baseless assumption to which we referred), the Mammalian 
 must be regarded as a more highly developed Fish ; and then it 
 is quite logical to say that the embryo of a vertebrate animal is 
 at first a Fish. Hence it was that I asserted above ( 1.), that 
 the view of the uniserial progression of animals was necessarily 
 connected with the prevailing idea as to the law of development. 
 But the Fish is not merely an imperfect vertebrate animal ; it 
 has besides its proper ichthyic characters, as development clearly 
 shows. 
 
 But enough ! I have attempted, in embodying the course of 
 development, to show also, that the embryo of Man is unques- 
 tionably nearer to the Fish than conversely, since he diverges 
 further from the fundamental type ; and upon this ground alone 
 has much been inserted that is problematical, as the umbilical 
 attachment of the Monotremata. In detail, this representation 
 can as little exhibit all the relations justly, as any other repre- 
 sentation of organic relations upon a plane surface even if the 
 investigation were complete, instead of being just begun. 
 
 Let us sum up the contents of this section as its conclu- 
 sion. The development of an individual of a certain animal 
 form is determined by two conditions: 1st, by a progressive 
 development of the animal by increasing histological and mor- 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 221 
 
 phological differentiation ; 2ndly, by the metamorphosis of a 
 more general form into a more special one. 
 
 Corollaries to the Fifth Scholium. 
 
 The history of development is the true source of light for the 
 investigation of organized bodies. At every step it finds its ap- 
 plication, and all the conceptions which we have of the mutual 
 relations of organized bodies must experience the influence of 
 our knowledge of development. It would be an almost endless 
 task to demonstrate this for all branches of investigation. Since, 
 however, those conceptions must spontaneously modify them- 
 selves so soon as the course of development is otherwise under- 
 stood, we may be permitted to bring forward a few points in 
 order to exhibit the influence of the view here set forth, and 
 thereby to justify the length at which it has been given. I have 
 endeavoured also to arrange these additions or appendices, so 
 that those which come first may contribute to the understanding 
 of the subsequent ones ; yet I have not been able always to suc- 
 ceed in doing this without intercalating many explanatory epi- 
 sodes. The reader will have also to complain of repetitions. 
 The greatest repetition of all however is, that all these considera- 
 tions are nothing more than reflexions of the contents of this 
 Scholium. 
 
 FIRST COROLLARY. Application of this Scholium to the 
 Doctrine of Arrests of Development. 
 
 It is no longer necessary to demonstrate that monstrous 
 growths can only be understood by knowing the normal course 
 of development. But I may be permitted to say a word con- 
 cerning arrests of development, since sometimes the understand- 
 ing of these malformations has been considered to be insepa- 
 rable from the view of the progression of the higher through 
 the lower forms of animals ; and it might thence be believed that 
 a contradiction of the latter view contradicted the doctrine of 
 arrests of development. This doctrine, however, is too well 
 based to be shaken by any alteration in the views which are en- 
 tertained with regard to the differences of form in the course of 
 the development of the higher organisms. Yet these malforma- 
 tions must not be regarded as the permanent forms of some other 
 
222 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 animal which the embryo had to pass through, but simply as a 
 partial stoppage at an earlier stage of their own development. 
 At times unquestionably there exists an obvious similarity with 
 some permanent form in particular parts ; but it is as readily 
 demonstrable that this similarity is not the condition of the mal- 
 formation, but the result of other relations, either, 1st, because 
 that form is nearer the fundamental type, in which case any 
 stoppage at an earlier period of development must necessarily 
 approximate the higher form to it ; or, 2ndly, because the altered 
 formative conditions may approximate the formative conditions 
 of the same part in another animal. Thus, for example, the nose 
 in Man is sometimes elongated into a proboscis, which reminds 
 one of the snout of a Pig. But the human nose never passes 
 through any stage of development in which it resembles the 
 snout of a Pig ; on the other hand, the Pig's snout, at the fourth 
 week of embryonic life, is not only similar to that of a human 
 embryo at an early period, but is in fact much more like the 
 nose of the adult Man than at a later period. 
 
 This relation agrees perfectly with the general law. The nose 
 of air-breathing Mammals in general does not project beyond 
 the jaw. Both the peculiarity of the Pig's snout, therefore, and 
 that of the human nose, arise subsequently without any transi- 
 tion of the one form through the other. If then a Man has the 
 snout of a Pig, it is no arrest of development, but the conse- 
 quence of an abnormal development, which has a result like that 
 in the Pig, where it is normal. While we are speaking of the 
 abnormal forms of the nose, I will call to mind the "Wolfs 
 jaws/' an indubitable arrest of development, but which is cer- 
 tainly no stoppage at any earlier form of animal. 
 
 SECOND COROLLARY. Application of the present View to the 
 Determination of the separate Organs in the different Forms 
 of Animals. 
 
 A closer acquaintance with the history of development will 
 sooner or later furnish us with the sole safe grounds in the de- 
 termination of the fitting denominations for, and in forming a 
 just judgment of, the organic parts of the different forms of 
 animals. At present a little may be done in this direction. 
 
 Since, in fact, every organ becomes what it is only by the 
 
K.E. VON BAER. PHILOSOPHICAL FRAGMENTS. 223 
 
 mode in which it is developed, its true import can only be re- 
 cognised by knowing the manner in which it is formed. At 
 present we judge for the most part in accordance with an inde- 
 finite feeling, instead of considering every organ only as an iso- 
 lated development of its fundamental organ, and determining 
 from this point of view the agreements and differences among 
 the different types. Every type has, in fact, not only its funda- 
 mental organs, but in each these are again divided into special 
 organs, which cannot be exactly what they are in any other 
 type. We therefore need some complete nomenclature, which 
 shall not merely apply the names of organs found in the verte- 
 brate type to the organs of other types, but shall give to them 
 special names when they have a different origin. This require- 
 ment will hardly indeed be satisfied in a century, but it is well 
 to call attention to it. In fact, the immediate consideration of 
 the perfect animal has often led to the recognition of the essen- 
 tial difference; perhaps, however, the determining conditions 
 have been less easily comprehensible. 
 
 First of all, I would refer to the question how the series of 
 ganglia upon the abdominal side of the Articulata is to be 
 named. They certainly do not constitute a spinal cord, since 
 this is composed of a nervous tube, which can be produced only 
 upon that scheme of development, which is followed in the Ver- 
 tebrata. As little are they comparable to the sympathetic nerve 
 of the Vertebrata, for they supply voluntary muscles, and in the 
 Articulata the plastic nervous system lies upon the dorsal sur- 
 face*. They are rather the terminations of the symmetrical 
 nerves of animal life, and, on that very account, as Weber and 
 Treviranus have already remarked, they are comparable to the 
 nerves and ganglia called spinal, in the Vertebrata, on account 
 of their insertion into the spinal cord. In the Articulata, how- 
 ever, these nerves have only one series of central and peripheral 
 
 * Some time ago, indeed, I was inclined to consider the so-called recurrent 
 nerves of Articulata to be their plastic nervous system, because I had traced 
 them a long way in the Crab ; however, I first became fully instructed on this 
 subject by a letter from Prof. J. M tiller. Mtiller, by his exactness in investi- 
 gation and delicacy in dissection, has succeeded in following out these nerves 
 through the whole extent of the plastic organs; and he has had the goodness 
 to communicate an excellent drawing of them to me. 
 
224 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 ends, because the whole animal part of the body is singly, and 
 not doubly symmetrical. 
 
 Whether the anterior pair of ganglia of the Articulata is to be 
 called a brain or not, depends wholly upon the signification given 
 to the word ( brain/ It is assuredly not the organ which we call 
 brain among the Vertebrata, for this is the anterior extremity of 
 that nervous tube which is absent in the Invertebrata. It is 
 rather the most anterior pair in the series of ganglia, and since 
 these are to be compared with the spinal ganglia of the Verte- 
 brata, the so-called brain appears to be for the longitudinal type 
 what the Gasserian ganglion is for the Vertebrata. This also 
 receives nerves of sense. A great importance appears to be 
 attached to the circumstance that it lies above the oesophagus. 
 This, however, appears to me to be an erroneous view. Properly 
 speaking, it only lies in front of the oesophagus. 
 
 If, in fact, we form a purely ideal notion of the longitudinal 
 type, the oral aperture is not placed at the anterior extremity, 
 but is directed downward, just as the oral aperture of the Ver- 
 tebrata is not situated at the anterior extremity of the vertebrate 
 type, but is placed somewhat posteriorly towards the abdominal 
 surface, for which reason a portion of the abdominal visceral 
 plates, the walls of the nose, lie in front of and above the oral 
 aperture. In the Chick it is very clear that the mouth opens 
 below. That in the Articulata the oral aperture belongs to the 
 lower half of the simple ring, is shown very clearly by the 
 Crustacea, and even by forms which exhibit the type in a less 
 altered form, as the Annelida. In the Earthworm, for example, 
 this relation of the so-called proboscis, which extends beyond 
 the oral aperture, is obvious. It contains the most anterior im- 
 perfectly developed rings. Now if in the Articulata the oral 
 aperture is in fact anterior, but yet upon the lower surface, and 
 corresponds with the most anterior extremity of the abdominal 
 surface, a pair of nervous ganglia must necessarily lie in front of 
 the oral aperture, and that they lie nearer the upper wall than 
 the posterior ganglia arises partly from the passage of the mouth, 
 partly from the very fact of its occupying the anterior extremity. 
 Very frequently it lies actually in the same plane with the others, 
 as in the Crustacea, where the mouth lies further back ; and in 
 Insects, where the head, with the oral aperture, is directed more 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 225 
 
 or less downwards. Only in the Annelida is its position de- 
 cidedly, though only a little, superior. (p. 235.) 
 
 p. 236. The same holds good of the cervical nervous band in 
 the Mollusca. It is not the organ which we call brain, not even 
 in the Cephalopoda, but in a manner the central part of a nervous 
 system, which, in its general relations, may be compared with 
 the plastic nervous system of the Vertebrata, but which takes 
 on a different form, inasmuch as it is not dependent upon a pre- 
 dominant brain and spinal cord. I can regard the so-called 
 brain of the Cephalopoda only as the cervical nervous band of 
 the Gasteropoda. In the former the ganglia are fused together, 
 in the latter they are more distinct. It is a centre of the plastic 
 nervous system, and can only be compared with the ganglia 
 which, in the Vertebrata, give off threads to the organs of the 
 senses and other parts of the head here, however, possessing 
 no predominating centre, but being subordinate to the brain. 
 
 If, in the Vertebrata, we consider the ganglion maxillare, 
 which also receives a nerve from the ear, in combination with 
 the ganglion caroticum, petrosum, Vidianum, ciliare, and the 
 threads which pass to the organs of sense and the pharyngeal 
 apparatus, we have a similar ring through which the commence- 
 ment of the digestive canal passes. 
 
 That every portion is to be understood only by its relation to 
 the type and by its development out of it, is taught still more 
 strikingly by other parts. The tracheae of Insects are indeed 
 aeriferous organs, but not the organ which we call the trachea 
 in the Vertebrata, because the latter is a development of the 
 mucous canal, while the tracheae of Insects arise either by histo- 
 logical differentiation or by involution of the external integu- 
 ment. Sometimes the same name has been used for different 
 organs only from the want of some other word the difference, 
 however, having been universally recognised. Thus no anato- 
 mist has regarded the wings of Insects as of the same nature as 
 the wings of Birds. In the feet, also, the essential differences of 
 the first joints have perhaps never been overlooked. A special 
 name has, with justice, been applied to the antennae. They 
 have no representative in the Vertebrata. But that they are 
 the wings of the cephalic ring is demonstrated not merely by 
 their position, but by their mode of development. They have 
 
 SCIEN. MEM. Nat. Hist. VOL. I. PART III. 15 
 
226 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 the same relative position as the wings in the pupa, with this 
 difference only, that they come from the head. 
 
 For the same reason also they agree with the lateral appendages 
 of the Crustacea. Whatever sensitive properties then these 
 antennae may have, they are yet never the organs of touch, 
 smell, or hearing of Vertebrata, but sensitive cephalic wings. 
 
 By these remarks I wish to render it intelligible, why every 
 type must be studied for itself, and possesses fundamentally 
 peculiar organs which are never to be found exactly the same in 
 any other type. In some cases, indeed, the distinction is but 
 small. The alimentary canal arises in all animals from the sur- 
 face which is turned towards the yelk. We have here the 
 smallest original difference. But in its further subdivision into 
 organs a distinction must be discoverable for the signification of 
 the separate organs ; it is indeed, as we know, often difficult to 
 recognise single divisions, as the stomach, &c. We shall suc- 
 ceed better if we determine every part only after other animals of 
 the same type. We know, for instance, how little the sexual 
 organs of the Massive series can be interpreted by those of the 
 Vertebrata. Still more striking is the tentacular system with 
 its vessels, w r hich is found in manifold variations among the 
 Radiata, for the ciliated bands of the Beroidae and the circular 
 vessel of some (if not of all) Medusae, should perhaps be re- 
 garded as modifications of this system. In the Articulata and 
 Vertebrata, however, we are acquainted with nothing similar. 
 It is perhaps peculiar to the peripheral type. 
 
 It will suffice merely to remark how little the notion that all 
 animals are only detached organs of Man corresponds with na- 
 ture. A few organs of the Vertebrata may, however, certainly 
 be said to contain within themselves the organs of the Massive 
 and Articulate series ; at least this appears to me to be probable 
 with regard to the organs of sense. 
 
 I shall perhaps, in another treatise, show that even in the 
 Vertebrata, development alone can guide us in interpreting the 
 signification of the organs. 
 
 THIRD COROLLARY. Application to the Affinities of Animals. 
 
 I have above ventured to assert (Schol. V. 1.) that the notion 
 of a uniserial succession of animals is the prevalent one, and I 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 22? 
 
 foresee that this assertion will be regarded as too sweeping, since 
 only a few investigators of the present day declare themselves 
 for it openly and decidedly ; in fact, not a few have pronounced 
 decidedly against it. I must therefore devote a few lines to 
 show the correctness of my statement. 
 
 That doctrine has, as I believe, far more unconscious than 
 conscious advocates. It seems to me, indeed, that a number of 
 conceptions, proceeding from the uniserial view, and belonging 
 to times long past, have propagated themselves, and without our 
 knowledge have given a colour to our view of organic affinities, 
 which is not the result of investigation. Are not the notions 
 that Cephalopoda or Crustacea are allied to Fishes, or even pass 
 into them, expressions of this fundamental view ? They could 
 hardly have proceeded from an immediate and free comparison 
 of their organisms. 
 
 Just as incomprehensible is the alliance between Echinoderms 
 and Mollusks. 
 
 Do not these attempts to build bridges between two distant 
 countries proceed from the endeavour to make each a link in a 
 chain? Having learnt, in fact, to understand the Crustacea 
 according to the type to which they belong, and regarding them 
 as the most developed forms of this type (with which I do not 
 agree), the next endeavour was to pass from them a step further. 
 In the same manner it was believed that a way led from the 
 highest Radiata to other regions. If, however, in accordance 
 with our view, we regard the separate forms or groups of forms 
 as variations upon a theme, we shall find that the transitions are 
 but few and isolated; consequences of the modifiability of a 
 form, but on that very ground not in themselves necessary and 
 determinate. We shall then not be misled into seeking agree- 
 ments between things which are heterogeneous, since we do not 
 regard the serial succession as the condition of the varieties of 
 animal forms. 
 
 The controversy, whether the Articulata or the Mollusca are 
 the higher, seems to me also to depend upon this view of a 
 uniserial development. If we properly comprehend the essence 
 of the different types, it appears easy enough to comprehend 
 how the plastic formations predominate in the one, in the other 
 sensitive and motor organs. The heart and the liver of Mollusks, 
 
 15* 
 
228 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 as well as their glandular system in general, then will not neces- 
 sitate us to place them higher than the Articulata. It would 
 be almost as one-sided to raise all these above the Mollusca, 
 although in general the greater variety in their vital manifesta- 
 tions might give them a fair claim to such a position. Funda- 
 mentally, however, each of these sections of the animal kingdom 
 has its own standard, which can only be determined by its type. 
 The greater the histological and morphological differentiation, the 
 higher, according to our view, is the perfection in the same type. 
 A less morphological differentiation is, however, always an ap- 
 proximation to the fundamental type. Thus, the Annelida, on 
 account of the similarity of their limbs, appear to us to be of 
 lower organization, notwithstanding their vascular system, whose 
 limitation in Insects is readily comprehensible, as a consequence 
 of the development of their tracheae. For us the Myriapoda do 
 not stand much higher, their manducatory instruments being 
 true cephalic feet and their head being but little separated 
 from the other almost identical rings. In the Thysanura and 
 Parasita a greater morphological differentiation has arisen. 
 And the structure of the true Insects is in them, as it were, 
 sketched out. 
 
 Just as gradual modifications of the Annulata may be re- 
 cognized through Myriapoda, Thysanura and Parasita, so may 
 such be observed through the Isopoda, Amphipoda and Stoma- 
 poda to the Decapoda, and through the Scorpionidae to the 
 Arachnida. 
 
 For what reason, however, the proper Spiders, or the Decapoda 
 among the Crustacea, are to be reckoned as more perfect than 
 the true Insects, is not clear. On account of their more perfect 
 vascular system ? This is only a consequence of a less active 
 interchange with the air, whose more powerful influence always 
 assists the development of animal life. 
 
 If, on the other hand, the Individualization of the organic 
 constituents is to be our standard of perfection, we observe in 
 the Decapoda, besides the slight histological differentiation which 
 to me is obvious, a tendency to compress the organs of sense, 
 the motor and the plastic organs, into one chief centre, in con- 
 sequence of \vhich the type is greatly modified, but its essential 
 parts become little separated ; in the Arachnida the plastic body 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 229 
 
 is at least separated from the animal; but in Insects with 
 metamorphosis, sensibility, irritability and plasticity are sepa- 
 rated, though indeed only in the perfect state. The most highly 
 developed among these, again, appear to me to be those whose 
 thoracic segments are not divided into many separate rings, 
 as in the Flea, the Coleoptera, and the Orthoptera, but when 
 they are collected into one. It is in these that the originally 
 similar parts, such as the feet and manducatory organs, have at- 
 tained the widest deviation. It is in these that we meet with 
 the best developed wings and the most various manifestations of 
 life. The Crustacea, indeed, possess an ear and a nose ; but we 
 must not forget that the head of Insects is small enough to 
 make such organs doubtful ; that a few investigators believe 
 they have found them, and that, at any rate, the senses are not 
 absent. 
 
 If we have succeeded in getting rid of all preconceived notions 
 of a gradual series, we shall consider each form to be a modifi- 
 cation of a more general form, and that these are modifications 
 of a fundamental type, and learn to comprehend them from this 
 point of view. We shall then take more pains to determine 
 the general affinities of each species, than its place in a univer- 
 sal progressive series. 
 
 If we seek, however, for the grade of development, we must 
 look for it only according to the degree of differentiation of the 
 parts, and within the type which belongs to the animal. That, 
 however, in fact, the preconceived conceptions of a progressive 
 series have led to the ordinary views, is what I shall endeavour 
 to establish and explain by yet a few examples. 
 
 We often hear of retrogressive metamorphoses of a whole 
 animal form or of a single organ ; can any clear conception 
 attach to these " Retrogressions/ 5 if we do not assume that the 
 form of some one animal is the condition of the form of some 
 other? This much, however, is certain, that such a view implies 
 the conception of a serial progression. 
 
 If, in fact, we arrange together obviously allied animals, and 
 then place them with their highest forms below those of another 
 series, we shall have a retrogression. I will but shortly refer to 
 the above (Schol. V. 3 a) example of Fishes. 
 
 In truth, the retrogressive metamorphosis of particular organs 
 
230 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 is spoken of, under the supposition that there is a progressive 
 development for every organ, from the Monad to Man, and that 
 this development is realized in accordance with the order of 
 progression of the animals, the particular exceptions from which 
 are now given. If, however, the organs are modifications of 
 fundamental organs, and these differ according to the scheme 
 of development (compare the following Corollary), there would 
 appear to be an erroneous assumption in this very supposition. 
 I believe, therefore, that if comparative anatomy is to be directed 
 to the ascertainment of the laws of formation, the only proper 
 way is, besides the constant reference to a fundamental type to 
 which the whole animal belongs, to compare the organs by 
 themselves in their different forms, as Burdach has attempted to 
 do in his g Physiology/ without arranging the forms in the same 
 order as the animals to which they belong would take in accord- 
 ance with their perfection in other respects. We shall thus 
 perceive how the general structure of the whole body of an ani- 
 mal, or its relation to the external world, operates in modifying 
 the form of particular organs, and so prevent ourselves from 
 being misled by prejudices. 
 
 That, however, these retrogressions in the development of 
 organs are only an appearance which depends upon a pre- 
 supposed uniserial development, is rendered most obvious by 
 their disappearance, if we arrange the animals according to 
 another organic system than that which was previously used as 
 a base. I bring forward one example out of many. If I am 
 persuaded that the Articulata are to be arranged in a progress- 
 ively developed series, and dispose them according to the de- 
 velopment of the vascular system, I may order them thus : 
 True Insects, Myriapoda, Arachnida, Annelida. In this case 
 the eyes are retrogressive through the series. Of the respiratory 
 organs, and the vascular system besides, it is at once intelligible 
 that the one appears retrogressive with respect to the other, since 
 these systems are antagonistically related. If I consider them 
 as modifications of a fundamental type, in which sometimes 
 one and sometimes the other system is more changed from the 
 simple fundamental form, then all retrogressions disappear. 
 
 What I have here said of the Articulata, in order to select an 
 obvious example, holds good not of them alone, n.or merely of 
 
K. E. VON BAER. PHILOSOPHICAL, FRAGMENTS. 231 
 
 the antagonistic relation of respiratory organs and vascular 
 system ; it appears wherever there are any manifold variations. 
 If we regard the different forms of Mammalia, we find for one 
 series of organs other affinities than for another. If we consider 
 the development of the animal part, which we may most readily 
 estimate by the skeleton, the Bats are very different indeed from 
 all the proper quadrupeds. We must suppose that they form 
 the most aberrant order. With respect to their digestive organs, 
 they resemble the Insectivora. Pallas, who in the Zoographia 
 Rosso- Asiatica unites the Bats closely with the Mole, appears 
 therefore to me to be as fully justified as Tiedemann, who about 
 the same time, in his ' Zoology/ separated them widely. For the 
 same reasons, Tiedemann unites the Seal with the Dugong, 
 while by Pallas they are widely separated. The one has regarded 
 the extremities, the other the teeth. What do such facts prove, 
 except that the different organic systems vary in different modes ? 
 The Mole and the Bat seek the same prey, the one in the air, 
 the other in the earth. Their motor organs therefore differ 
 according to the place of their residence. The Dugong arid the 
 Seal are both aquatic, and have fin-like extremities, but what 
 they seek is totally different; so are their dentition and their 
 stomachs. 
 
 Under such circumstances, does not an approximation to Man 
 give for every organic system a different series of animals ; and 
 if this be so, are not "retrogressions 5 ' without meaning? In 
 truth, Man is only in respect of his nervous system, and of that 
 which is connected with it, the highest form of animal. His 
 erect progression is only a consequence of the greater develop- 
 ment of his brain, since we find everywhere that the more the 
 brain preponderates over the spinal cord, the more it raises itself 
 above it. If this remark be well founded, all corporeal distinc- 
 tions between Man and other animals may be reduced to cerebral 
 development ; and in that case the pre-eminence of man is only 
 a partial, although the most important one. One must be com- 
 pletely prejudiced, in fact, not to see that the stomach of the 
 Ruminant, which changes grass into chyle, is more perfect than 
 the stomach of Man. (p. 242.) 
 
232 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 (p. 257.) FOURTH COROLLARY. 
 
 ******* 
 
 But from what has been said, it seems to follow that every 
 principal type of animal organization follows a special scheme 
 of development ; indeed nothing else could have been expected, 
 since the mode in which the parts are united together can only 
 be the result of the mode of development. In reality, therefore, 
 I might have used, instead of Type and Scheme, a common term 
 expressing both. I have only kept them separate in order so 
 to make it obvious, that every organic form, as regards its type, 
 becomes by the mode of its formation that which it eventually is. 
 The scheme of development is nothing but the becoming type, 
 and the type is the result of the scheme of formation. For that 
 reason the type can only be wholly understood by learning the 
 mode of its development. This introduces differences into the 
 germs, which at first are alike in all essential points. Different 
 conditions or formative powers must act upon the germ in order 
 to produce this multiplicity, on which head we shall by and by 
 raise one or two queries. 
 
 Here, however, we must add the remark, that the original 
 agreement of all animal germs does not completely disappear 
 even in the perfect forms, and that we have to seek the most 
 profound distinctions among animal forms, which are attainable 
 by us in the mode of development. 
 
 With respect to the original agreement, I would call to mind, 
 that, according to the Corollary of the Second Scholium, every 
 animal is at first a part of its mother, that it becomes indepen- 
 dent either by the immediate development of the parent herself, 
 or after the action of a male principle, and that then the first 
 act of independence consists in passing into a vesicular form ; 
 either the whole becoming the body of the new animal, or the 
 future body (the germ) separating itself from the merely nutri- 
 tive substance which surrounds it. Here animals and plants 
 diverge, since the latter do not invest the nutritive matter. 
 The vesicular form, therefore, is the most general character of 
 the animal ; the contrast of external and internal surface is the 
 most general, and therefore the most essential contrast in the 
 animal. (See above, Schol. V. 4 d.) 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 233 
 
 There remains yet another agreement between all forms of 
 development. In all animals, namely, which at an early period 
 possess a germ and a yelk, the investing germ becomes divided 
 into many layers ; that turned towards the yelk is the plastic 
 receptive layer; that turned from it, the more animal, even 
 though its outermost border should become merely a limiting 
 organ, and clothe itself more or less with an excreted non-vital 
 layer. That now the vascular system, if it is otherwise sepa- 
 rated from the digestive cavity, is formed external to it nearer 
 to the animal part ; that in the animal part, muscles, nerves, &c., 
 become separated, appears also to belong to the Idea of the ani- 
 mal in general ; and the further this histological differentiation 
 goes, the more developed do we call an animal. 
 
 Wholly different from this, however, is the relative position 
 of the parts. This is determined by the external form of the 
 development. 
 
 We have distinguished four principal forms, or, as we have 
 called them, Schemata of Development : 
 
 Radiate Development (Evolutio radiata), which, proceeding 
 from a centre, repeats similar parts peripherally. 
 
 Coiled Development (Evolutio contorta), in which similar parts 
 are twisted round a cone or other space. 
 
 Symmetrical Development (Evolutio gemma], in which similar 
 parts are distributed from an axis on both sides to a sutural line 
 opposite to the axis. 
 
 Double Symmetrical Development (Evolutio bigemina], in 
 which from an axis similar parts are disposed on both sides 
 above and below, and are united at two sutural lines ; so that 
 the inner layer of the germ is closed below and the upper layer 
 above. 
 
 We know that in the higher Vertebrata the Germ soon divides 
 into two parts, an inner, which may especially be termed the 
 Embryo ; and an outer, which may be called the Germinal mem- 
 brane. I have already remarked that the former is nothing but 
 a part of the germ, which is metamorphosed according to the 
 scheme of development peculiar to every animal, whilst the peri- 
 pheral part remains behind in its development. 
 
 In Mammalia, Birds, and Reptiles, the middle part is but 
 small in proportion to the outer portion, and it gradually sur- 
 
234 K. E. VON BAEB. PHILOSOPHICAL FRAGMENTS. 
 
 rounds the yelk, forming the abdominal suture. In the Frog, 
 indeed, the external part of the germ is very thick, yet, as I 
 believe, a separation into embryo and germinal membrane is un- 
 deniable ; for the middle portion at the period in which the back 
 closes is still very much thicker, and the limitation is tolerably 
 well marked between the abdominal plates and that exterior por- 
 tion which I regard as the germinal membrane. The former 
 grow together towards the suture of the abdomen. In very 
 young Pikes, also, in which the germinal membrane is much 
 thinner and more transparent, this appeared to me to be the 
 case. I saw beside the trunk of the vertebral column a pair of 
 very narrow dark striae, the commencing abdominal plates. It 
 may hence, I believe, be affirmed universally of the Vertebrata, 
 that the embryo will surround the yelk with its abdominal plates, 
 although this has previously been invested by the germinal 
 membrane. It is the same in the Articulata. Their lateral 
 plates are clearly distinguished by their thickness from the 
 proper germinal membrane. They also surround the yelk. In 
 the Mollusks, however, the whole germ appears to change 
 equally. It cannot therefore be said of them that the embryo 
 grows round the yelk, but more justly, that from the moment of 
 fecundation it remains as its investment ; for a differentiation of 
 the germ into embryo and germinal membrane is not perceptible ; 
 the whole germ, rather, becomes the embryo. 
 
 The same would very probably also take place in the radiate 
 type, if any animal form from this series were developed from a 
 true ovum, of which we have no knowledge*. If they should 
 all be developed from mere germ-granules, the relation is still 
 more apparent; for every germ-granule, so far as we know, is 
 developed as a whole, and is nothing but a germ without a 
 yelk. 
 
 We must not overlook here an interesting relation. In those 
 ova in which the germ is clearly separated into an embryo and 
 a germinal membrane, it is the animal part of the embryo which 
 
 * At present hardly anything could be of more interest for the history of 
 development than the observation of the development of the Asteridae, and 
 after these of the Cephalopoda. According to Cavolini, the latter have a yelk- 
 sac depending from the mouth (AbhandL iiber die Erzeugung d. Fische und 
 Krebse uebefs. von Zimmermann, 1792, p. 54), which is difficult to understand. 
 
K. E. VON BAEB. PHILOSOPHICAL FRAGMENTS. 235 
 
 causes this separation. It is the animal part which grows so 
 much, that we observe the marking off of the embryo from the 
 germinal membrane. It is only after this has determined the 
 whole form of the animal, that the plastic part appears to attain 
 a certain degree of independence, which in the Articulata is often 
 limited to a mere separation, the separate organs arising subse- 
 quently, but which in the Vertebrata has sufficient power to 
 cause a symmetrical development of the animal part. Of the 
 action of the plastic part upon the animal, we can but detect a 
 trace here and there. It is otherwise in the Mollusca. The 
 plastic part becomes independent very soon, and has a decided 
 influence upon the external form. We see how the essential 
 character of the animal manifests itself very early, and develop- 
 ment affords a justification for the name of Plastic animals which 
 has been given to the Mollusca. Hence also we shall be better 
 able to judge how far the Mollusca may be justly compared with 
 the vegetative section of the body of the Vertebrata ; in its pre- 
 dominant character namely, not according to the sum of all its 
 separate parts. In the Mollusca, it is also a relatively animal 
 part which occupies the whole periphery, and is principally 
 developed in the foot of the Gasteropoda. Compared with 
 other animals, they are living bellies ; but since these bellies are 
 independently developed, without the influence of a more highly 
 organized animal part, they have also a part which for them is 
 more animal, and it is that which originally formed that surface 
 of their germ which was turned from the yelk. 
 
 In all four forms the surface of the germ which is turned 
 towards the yelk does not change its position relatively to the 
 latter, but retains it, and becomes the digestive surface of the 
 perfect animal. In all forms, moreover, the peripheral part of the 
 perfect animal is the external surface of the germ, that which is 
 turned away from the yelk. I therefore believed myself to be 
 justified in supposing that it is the relation to the yelk which in 
 the germ produces the primary differentiation into an animal 
 and a plastic layer. 
 
 But it is not in all animals that the whole outer layer of the 
 germ remains exterior. In the Vertebrata, the one half of the 
 doubly symmetrical development encloses a part of the outermost 
 surface, and changes into the nervous tube, the spinal cord with 
 
236 K. E.VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 the brain, parts which must therefore necessarily be absent in 
 other types. I would here render perfectly obvious how it is 
 the scheme of development which produces the principal cha- 
 racter of the animal. If we suppose that, in any articulate 
 animal which is in the earliest stage of its development, a part 
 of the germ should become raised up on both sides, and so 
 enclose a portion of the external surface, the enclosed part 
 would be an animal central portion. The internal organs 
 would all have the same relation to it as in the Vertebrata, ex- 
 cepting the plastic nerves, which by the influence of the ani- 
 mal nervous system appear to be approximated to this last in 
 the Vertebrata. 
 
 In relation to the external world, however, all the internal 
 organs would be inverted, since the central part itself would 
 lie downwards. If we were to invert the animal, all the outer 
 parts, the extremities and the organs of sense, would be dis- 
 placed ; and supposing that the extensor and flexor sides had 
 not undergone inversion by the addition of the new central part, 
 these also. 
 
 Hence we conclude, that, by the origin of a central part for the 
 animal body, the position of the plastic organs, and their relation 
 to the nearest animal layer, have indeed remained unchanged ; 
 but their relation to the external world, and all which represents 
 this relation in the body, has become inverted. In the former 
 case, where the course of development is simply symmetrical, 
 the central line from which it proceeds becomes the flexor side 
 of the animal ; with a doubly symmetrical development, the side 
 from which it proceeds becomes the extensor side. Towards the 
 flexor side, the extremities and the feet are developed. By this 
 it shows itself to be that which is most essentially turned towards 
 the planet. Towards the extensor side, that turned from the 
 ground, the organs of the senses are developed. 
 
 I commenced this Corollary with the remark, that animals 
 ought to be divided according to their mode of development, 
 and I have shown sufficiently at length that the principal types 
 have their own form of development. I may be permitted to 
 point out here, in a few words, that the safest guide for further 
 division would be found in the history of development, if we 
 were acquainted with it with sufficient exactness, in the different 
 
K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 237 
 
 classes and families of animals. If we keep this in view, we 
 shall easily recognise the true Insects as a higher stage of deve- 
 lopment than the Arachnida and Crustacea. We shall hold the 
 Batrachia to be different enough to separate them, with De 
 Blainville, from the Reptilia as a distinct class. And, in fact, 
 what have they in common with the latter, than that they are 
 not Fish, nor Birds, nor Mammals ? 
 
 SCHOLIUM VI. General Result. 
 
 If we review the contents of all the Scholia, a universal result 
 proceeds from them. We found that the action of reproduction 
 consists in elevating a Part into a Whole (Schol. II.) : that, in 
 the course of development, its independence in relation to that 
 which is around it increases (Schol. II.), as well as the determi- 
 nateness of its form (Schol. I.): that in the internal development, 
 the more special parts are developed from the more general, and 
 their speciality increases (Schol. III.) : that the individual, as 
 the possessor of a determinate organic form, gradually passes 
 from the more general form into the more special (Schol. V.) ; 
 and therefore the most general result of these investigations and 
 considerations may well be thus expressed : 
 
 The history of the development of the individual is the history 
 of its increasing individuality in all respects. 
 
 This general result is indeed so simple, that it would seem 
 to need no demonstration, but to be cognizable a priori. But 
 we believe that this simplicity is only the stamp and evidence of 
 its truth. If the nature of the history of development had been 
 from the first so recognized as we have just expressed it, it 
 would and must have been a deduction thence, that the indi- 
 vidual of any particular animal form attains it by passing from 
 the more general into the special form. But experience every- 
 where teaches that deductions become much more certain if 
 their results are previously made out by observation. Man 
 must have received a greater spiritual endowment than he ac- 
 tually possesses for it to be otherwise. 
 
 If, however, the general result which has just been expressed 
 be well based and true, then there is one fundamental thought 
 which runs through all forms and grades of animal development, 
 
238 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 
 
 and regulates all their peculiar relations. It is the same thought 
 which collected the masses scattered through space into spheres, 
 and united them into systems of suns ; it is that which called 
 forth into living forms the dust weathered from the surface of 
 the metallic planet. But this thought is nothing less than Life 
 itself, and the words and syllables in which it is expressed are 
 the multitudinous forms of the Living. 
 
 DESCRIPTION OF FIGURE. 
 t 
 
 Ideal figure of the organic movements in Verte- 
 brata. The body of the animal is supposed to 
 be transparent, so that the outline only is seen. 
 The outline of the heart is indicated (the right 
 auricle is drawn rather too much backwards). 
 The view is from the dorsal surface. 
 
 1'. Course of the red blood into the left ventricle. 
 
 1 . Course of it out of the left ventricle. 
 
 2. Course of the venous blood from the anterior half 
 
 of the body into the right auricle. 
 
 3. Course of the venous blood from the posterior 
 
 half of the body into the right auricle. 
 
 4. Course of the portal blood. 
 
 5. Course of the respired air. 
 
 6. Course of the food from the pharynx into the 
 
 ossophagus. 
 
 7. Course of the chyme from the stomach into the 
 
 intestine. 
 
 8. Course of the faeces. 
 
 9. Course of the ova. 
 
 [T. H. H.] 
 
W. HOFMEISTER ON THE DEVELOPMENT OP ZOSTERA. 239 
 
 ARTICLE VIII. 
 On the Development q/Zostera. By W. HOFMEISTER. 
 
 [From the Botanische Zeitung, Feb. 13th & 20th, 1852.] 
 
 THE peculiar physiological phaetiomena exhibited by Zoster a, 
 above all the unique formation of the pollen and the strange 
 structure of the embryo, have frequently and from an early 
 period drawn the attention of botanists to this remarkable genus 
 of plants. In most of the larger illustrated works devoted to 
 the local floras of Europe, the figures of Zoster a are accompanied 
 by careful and more or less accurate microscopic dissections, as 
 in Schkuhr, Hooker's Flora Londinensis, Reichenbach's Icones, 
 Schnizlein's Iconographie der naturlichen Familien, &c. The 
 form of the embryo has been a subject of discussion for almost 
 every author who has studied the comparative import of the 
 parts of the seedling plants of Monocotyledons*. Fritzschef 
 made known the curious condition and the circulation of the 
 contents of the pollen-cells ; Gronland J has very recently pub- 
 lished a contribution to the knowledge of Zostera marina, a 
 series of most acceptable microscopic researches on the develop- 
 mental history: imperfect, however, in reference to several of 
 the most interesting questions, especially to those connected 
 with the origin of the pollen and of the embryo. The following 
 essay, the materials for which I owe to the kindness of Prof. 
 Nolte of Kiel, will in some points complete, in others correct, 
 the paper published by Gronland. 
 
 The inflorescence of Zostera, like that of the nearly allied 
 Potameae, is relatively terminal : the metamorphosed end of a 
 
 * Gartner, De Fructibus, 1. 1 9 ; Bernhardi, Litintea, Bd. vii.; Jussieu, Annales 
 dea Sc. nat. 2*ne Ser. t. xi. p. 356. 
 
 t Mem. de V Acad. de St. Petersbourg par div. Sav. t. iii. p. 703. pi. 3. 
 
 I BoL Zeitung, vol. ix. p. 183 (1851). 
 
 The plants which Prof. Nolle was kind enough to forward to me repeatedly, 
 at different seasons, were perfectly fresh when they arrived at Leipsic (30 or 40 
 hours after their removal from their native locality) ; even the adherent Chato- 
 morphce and Polysiphoniae retained their vitality unaffected. 
 
240 W. HOFMEISTEB ON THE DEVELOPMENT 'OF ZOSTERA. 
 
 branch. In Zostera marina, when the formation of flowers 
 commences, both the previously inert axillary buds and also the 
 terminal shoot of the little-branched or even simple sterile plants, 
 become converted into inflorescences. In Zostera minor the rule 
 is for axillary sprouts standing far back from the sterile terminal 
 shoot, to become transformed into blossoms. This distinction 
 between the two species, so striking at first sight, appears to 
 depend principally upon the fact that in Zostera marina the old 
 portions of the stem die away rapidly, within a few months, 
 from behind forwards, while in Zostera minor they persist for 
 more than a year. 
 
 When the terminal bud of a plant of Zostera marina enters 
 upon a transformation into a spadix, the ordinary series of 
 linear stem- leaves with sheathing bases (having the divergence |), 
 becomes interrupted by a cylindrical leaf-sheath, devoid of 
 any indication of a lamina, the two lateral borders of which 
 sheath, enclosing the terminal bud, adhere firmly together. The 
 axillary sprouts which become blossoms arise with a similar 
 sheath. The next internode of the flowering sprout bears a leaf 
 like the stem-leaves (laub- blatter), but with a comparatively shorter 
 lamina, which, like the leaves of the Zostera generally, has a 
 divergence of \ from the leaf next older than itself. The 
 sheathing base of this leaf envelopes the inflorescence, i. e. the 
 expanded, flat, long-protracted end of the stem, that surface of 
 which turned away from the last leaf bears the anthers and 
 ovaries. 
 
 From the axil of the sheathing bract (vorblatt) of the fertile 
 sprout (PI. VI. fig. 1 a] arises a shoot, resembling in all respects 
 its parent sprout, with which it is coalescent for a considerable 
 distance (fig. 1 b). At the place where the cohesion ceases the 
 new sprout bears its first, sheathing leaf (fig. 1 b 1 ). This 
 diverges J of the circumference of the stem from the bract 
 (vorblatt} of the sprout of the preceding rank, and is parallel 
 with the stem-leaf (laub-blatt) in the axil of which that arises. 
 The sheathing leaf is succeeded by a stem-leaf (laub-blatt) 
 (fig. 1 b 2 ), above which the sprout terminates with the inflores- 
 cence (fig. 1 b). The axil of its lowest, sheathing leaf sends out 
 a fructifying branch of a new rank (fig. 1 c), and so on, till the 
 exhaustion of the growing power of the blossoming plant, in 
 
W. HOFMEISTER ON THE DEVELOPMENT OP ZOSTERA. 241 
 
 Zostera marina, to a series of twelve, in Zostera minor only of 
 six ranks. 
 
 The rudiments of the first spadix of Zostera marina appear at 
 the beginning of spring, those of Zostera minor in the middle 
 of summer. From then until the period of maturation of the 
 first seeds (in Z. marina at the beginning of July, in Z. minor 
 the beginning of September), new flowering sprouts arise suc- 
 cessively in the axils of the bracts (vorblatter) of their predeces- 
 sors, so that, from the middle of May forwards, every fertile 
 plant of the common Zostera exhibits a series of distantly situated 
 stages of development of the floral organs*. 
 
 When arising out of the axil of the sheathing leaf of the pre- 
 ceding sprout, the axis of a new rank, terminating in an inflores- 
 cence, presents itself as a hemispherical papilla (fig. 1 d), the 
 side of which facing the parent sprout coheres with the latter up 
 to the point where the new shoot forms its first, sheathing leaf, 
 by the simultaneous multiplication of a zone of cells situated 
 close underneath its apex. The multiplication of the cells of 
 both organs, axis as well as leaf, in the longitudinal direction, 
 commences with a repeated subdivision of their apical cells in 
 the axis of a single one, in the leaf of an incomplete crown of 
 similar cells by means of alternately obliquely inclined walls. 
 
 The fertile shoot forms its single stem-leaf (laub-blatt), oppo- 
 site to the leaf-sheath, shortly after the latter breaks forth. The 
 bud of the sprout of the succeeding rank appears simultaneously 
 in the axil of the basilar sheath. 
 
 The stem-leaf (laub-blatt) makes its appearance as a flat 
 cellular mass embracing the end of the stem so completely as to 
 leave only a narrow slit. It first grows longitudinally, by re- 
 
 * The interpretation of the series of sprouts of the flowering Zostera given 
 above, placed beyond doubt by investigation of the development, is also the only 
 one possible, looking exclusively at the condition when complete. Neither is 
 the supposition admissible that the flowering sprouts, upwards from the sheath- 
 ing leaf, are a series of equivalent secondary axes of a main axis bearing only 
 sheathing leaves, for the sheath is opposite to the sprout terminating as an in- 
 florescence ; nor is that which would make the inflorescence an axillary bud of 
 the stem-leaf (laub-blatt) which sheathes the spadix with its base, for this as- 
 sumption would lead us to expect each couple of leaves of the main axis, a 
 stem-leaf (laub-blatt) and a leaf-sheath, to stand regularly one above the other; 
 a conception untenable when we recollect the position of the leaves of the 
 sterile plant of Zostera. 
 
 SCI EN. MEM. Nat. Hist. VOL. I. PART III. 16 
 
242 W. HOFMEISTER ON THE DEVELOPMENT OF ZOSTERA. 
 
 peated subdivision of the cells of its upper border. The multi- 
 plication of these cells, on the side turned away from the slit, of 
 this organ (hitherto resembling a cylinder slit up lengthways), 
 soon outstrips that of the apical cells of the other half of the 
 leaf: the riband-shaped lamina grows out from the sheath. The 
 multiplication of the cells at the apex of the leaf ceases early, 
 while a very active and long persistent increase occurs in those 
 of the base. 
 
 After the rudiment of the stem-leaf (laub-blati) has been 
 formed, the end of the stem above it changes its form. It be- 
 comes widened out by a multiplication of its cells, predominantly 
 in the direction parallel to the surface of the leaf, and it assumes 
 the shape of a thick spatula, slightly concave at the side nearest 
 the next (younger) sprout. The rudiment of the flattened spadix 
 is now unmistakeable in the end of the axis. The longitudinal 
 growth of the spadix is continued by a frequently repeated divi- 
 sion of its apical cells by means of walls inclined alternately 
 towards the upper and lower surfaces of the leaf-like organ. 
 The cells in the median line and at the margins of the spadix 
 remain long capable of multiplication; constituting strings of 
 cambium structure. On the other hand, two broad strips of 
 cellular tissue, parallel to the lateral borders of the spadix, early 
 cease to increase. With the exception of those composing the 
 epidermis, all these cells become separated from each other at 
 their angles; air becomes excreted in the intercellular spaces 
 (fig. 3). The cells of both the marginal strips of cambium on 
 the upper side of the spadix become greatly multiplied through 
 repeated division by walls parallel to its surface. In this way 
 are formed two swollen tracts of cellular tissue, which, in their 
 further development, become curved strongly inwards so as to 
 cover in a great part of the upper surface of the spadix, through 
 the resistance which the sheath of the stem-leaf (laub-blatf), 
 closely enveloping the inflorescence, opposes to the unfolding of 
 them. In Zoster a minor little leaf-like structures arise upon the 
 spadix near the lateral margins of its upper face, and these lie over 
 the surface of the spadix like clamps or claws. Zostera marina 
 exhibits no trace of such organs. From the median streak of the 
 spadix, which becomes greatly expanded by the active multiplica- 
 tion of its cells, arise the anthers and ovaries, upon the upper face, 
 
W. HOFMEISTER ON THE DEVELOPMENT OF ZOSTERA. 243 
 
 arranged with strict regularity, as is well known, according to 2, 
 in such a manner that single anthers alternate with single ovaries 
 in each of the two longitudinal rows of floral organs, and organs 
 of different sex constantly stand next together horizontally. 
 
 The anther first appears as a longish papilla of cellular tissue, 
 the larger diameter of which is parallel to the longitudinal line 
 of the spadix (fig. 4 a). The two ends of the young anther soon 
 appear curved outward to some extent ; they rapidly increase in 
 magnitude, and become globular protuberances (fig. 3 a, a), which 
 gradually become spindle-shaped through continued rapid mul- 
 tiplication of the cells. Thus each anther consists of two appa- 
 rently independent, moderate-sized halves, which are connected 
 together by a comparatively long riband-shaped cellular body, 
 the altered connective, attached to the spadix by the narrow 
 edge*. 
 
 At the time when the half of the anther is passing from the 
 globular into the ovate form, two parallel rows of cells lying in 
 its longitudinal axis, take on a different character from the sur- 
 rounding tissue (PL VI. figs. 5-7). The process of division ceases 
 in the former, while the three layers of cells of the latter continue 
 to multiply. The cells of these parallel rows are the primary 
 parent-cells of the pollen. Their form is pretty nearly that of a 
 cube (fig. 7) ; in their subsequent development they become 
 elongated into short prisms, in a direction inclined downwards 
 from the surface of the spadix. 
 
 The pollen-cells are developed from these cells through re- 
 peated longitudinal division, by means partly of perpendicular, 
 partly of horizontal walls (figs. 6-12). The process of their 
 formation is thus very unlike that occurring in the great 
 majority of Phanerogamia. There is not the slightest indica- 
 tion of parent-cells becoming isolated, or of special parent- 
 cells. There occurs in the primary parent-cells a series of 
 " halvings " or bisections in only two directions, differing in 
 no respect from vegetative cell-multiplication ; the last genera- 
 tion, alone, of the daughter-cells become disconnected and so 
 form the pollen-cells. This development of the pollen of Zoster a 
 
 * This part of the development of the anther, very completely treated and 
 correctly figured by Grbnland, loc. cit. 187, is mentioned here merely for the 
 sake of giving a connected account. 
 
 16* 
 
244 W. HOPMEISTER ON THE DEVELOPMENT OF ZOSTERA. 
 
 is not, however, altogether an isolated phaenomenon ; the earlier 
 stages of formation of the pollen-masses of the Asclepiadaceae 
 resemble it most perfectly. In the anther of the Asclepiadaceae, 
 the laws of growth of which correspond on the whole to those 
 of the rudimentary spadix of Zostera, and which, like this, is 
 at an early age shaped like a little sloped-off spatula with a 
 strongly rounded back, two groups of longitudinal rows of cells 
 become the primary parent-cells of the pollen*. Extending 
 considerably inwards in a direction perpendicular to the surfaces 
 of the anthers, they acquire a different character from the sur- 
 rounding tissue and assume the form of recumbent prisms. By 
 a series of longitudinal and transverse divisions parallel to the 
 long axes of these prisms, the rudiment of the pollen-mass be- 
 comes a group of narrow cells of a length six to ten times greater 
 than the cross diameter. At this stage of development it cor- 
 responds perfectly to the contents of a chamber of the young 
 anther of Zostera. But in the Asclepiadaceas there now succeeds 
 a many times repeated division of the elongated parent-cells, by 
 means of walls perpendicular to their long axes, whereby the 
 pollen-mass becomes transformed into a body composed of trans- 
 verse rows of cubical cells the special-parent-cells. These 
 special-parent-cells become polyhedral by unequal expansion of 
 the whole mass, and then a pollen-cell originates in each. 
 
 The pollen -cell of Zostera appears at its origin as an obtuse- 
 angled, almost cylindrical sac, the long diameter of which is 
 three or at most four times as great as the cross diameter (figs. 
 11-13). The nucleus, which it is difficult to make visible, 
 vanishes at an early period. 
 
 With the formation of the pollen commences a very consider- 
 able enlargement of the pollen-chambers (loculi), by vigorous 
 multiplication and expansion, in a tangental direction, of their 
 
 * Schacht (Das Mikroskop, Berlin 1851, p. 154) assumes that only one lon- 
 gitudinal row of cells becomes converted into primary parent-cells. His figure 
 (tab. iii. fig. 8) shows the cross section of the attenuated upper end of an already 
 further developed group of such cells (a pollen-mass), where one primary 
 parent-cell, divided into two, is visible. Longitudinal and transverse sections 
 of earlier conditions show, beyond doubt, that several longitudinal rows of cells 
 of the tissue of the rudimentary anther, of unlike value (in Nageli's sense, t. e. 
 not all products of an equal number of subdivisions), take part in the forma- 
 tion of the pollen. I shall recur to this subject in another place. 
 
W. HOFMEISTER ON THE DEVELOPMENT OF ZOSTERA. 245 
 
 cell-walls. The pollen-cells, constantly growing longer, keep pace 
 with the enlargement of the loculi ; they thus soon attain a con- 
 siderable (fig. 14), and finally, in proportion to the permanently 
 small cross diameter, quite an enormous length (in the ripe 
 anther as much as 3 lines). They retain throughout their 
 original direction, inclined downwards from the surface of the 
 spadix. Toward the close of the increase of length they displace 
 the innermost of the three layers of cells which originally formed 
 the outer wall of each loculus. A cellulose membrane becomes 
 first distinguishable on the pollen when the long diameter is 
 about eight times the cross diameter, and at that period it is yet 
 extremely delicate. As the pollen approaches maturity it be- 
 comes tougher, but no secretion whatever of an exine occurs ; 
 as was made known by Fritzsche. The tendency of the pollen- 
 cell to expand its membrane often outruns the growth of the 
 walls of the loculus, towards the approach of maturity. The 
 pollen-cells, restrained in their natural extension, then frequently 
 exhibit curvatures or curling of the ends and protrusions of 
 various forms (PL VI. fig. 15 b). 
 
 As long as the longitudinal growth of the pollen lasts, the 
 granular-mucilaginous fluid contents are uniformly diffused in 
 the cell. Toward the time of maturity we find longish cavities 
 in the mucilage, filled with a fluid of less refractive power, and 
 these are finally blended into a single cavity lying in the axis. 
 At this period we may frequently observe the active currents in 
 the dense, mucilaginous coating (containing numerous granules) 
 of the inside of the cell-wall ; more distinctly in proportion as 
 the pollen-cell is riper and the temperature of the surrounding 
 water higher. Two principal currents may be distinguished, 
 one ascending, the other descending ; one of these is ordinarily 
 stronger and of larger size. The moving mass splits up here 
 and there into several arms, sometimes becoming again confluent, 
 between which remain isolated spaces occupied by motionless 
 and more transparent fluid (fig. 15.) The pollen-cells in which 
 a particularly rapid circulation occurs are always greatly swollen 
 up (lying in fresh water), and ordinarily burst in the course of 
 a few minutes during the observation. Change of temperature 
 in the surrounding medium has a most decided influence on the 
 circulation in the pollen-cell. When warmer or cooler water 
 is applied upon the object-holder, one of the two currents is 
 
246 W. HOFMEISTEB ON THE DEVELOPMENT OF ZOSTERA. 
 
 greatly strengthened, the other weakened, sometimes even so 
 far as to disappear. It is not improbable that the different 
 temperatures of the ends of the filiform cell form one of the 
 causes on which the phaenomena of motion of the granular 
 mucilage are dependent. 
 
 The investigation of the development of the pollen of Zostera 
 is very difficult. The contents of the cells of the young anther, 
 especially those of parent-cells of the pollen-cells, and of the 
 latter themselves, are extremely sensitive to the action of pure 
 water. This holds in a still higher degree of the pellicle form- 
 ing the coat of the young pollen. When an available preparation, 
 a very delicate longitudinal section of a young half-anther, is 
 placed under water, the membranes of the young pollen-cells 
 swell up, and, with their mucilaginous contents, instantly run 
 together into a shapeless jelly. The only method of examining 
 the young anther is to place it in a saline solution ; I employed 
 here, as in similar cases, a saturated solution of carbonate of 
 ammonia. No safe conclusions can be obtained regarding the 
 structure of the anther, or the course of development of the 
 pollen, without making sections. The connection of the different 
 tissues is so intimate in the young anther, that it is quite im- 
 possible to extract uninjured either the parent-cells of the pollen 
 or the very young pollen- cells*. 
 
 The first visible rudiment of the ovary is a flat papilla (fig. 3 b) 9 
 composed of few 7 cells, which, increasing in size, soon acquires 
 the form of a horse-shoe with the convex side turned towards 
 the median line of the inflorescence (fig. 4 b), the rudiment of a 
 leaf attached upon the surface of the spadix. In a short time, this 
 becomes closed in so as to form an annular wall of cellular 
 tissue, within which appears a little roundish mass of cellular 
 tissue (fig. 160), approached near to the inner border; this is 
 the axillary bud of the carpel the ovule. The circular wall 
 becomes developed particularly quickly on the side next the 
 base of the spadix. It bulges out at this place, while it grows 
 
 * The globular cells which Gronland mentions as the contents of the loculi 
 of the young anthers, and likewise figures (loc. clt. p. 188, figs. 18, 19, 20), 
 I was unable to find, at any stage of development of the anther. The closely 
 packed, straight and parallel pollen-cells always completely filled up the cavity 
 of the anther. Probably those appearances depended on some of the cells of the 
 lax and mucilaginous innermost layer of the wall of the anther being accidentally 
 detached in the preparation of the object. 
 
W. HOFMEISTER ON THE DEVELOPMENT OF ZOSTERA. 247 
 
 up into an obtusely conical hollow mass of cells perforated at 
 the apex (fig. 17). The ovule unfolds itself within the bulging 
 portion of the cavity, becoming curved downward. Simultane- 
 ously with the sudden commencement of the very considerable 
 elongation of the perforated mouth of the young ovary, to form 
 the canal of the style, begins the formation of the two integuments 
 (fig. 18). They arise close beneath the summit of the young 
 ovule, by a pretty nearly simultaneous commencement of rapid 
 multiplication in two zones of cells ; the development of the outer 
 coat of the ovule begins immediately after the inner coat becomes 
 visible. The lower part of the ovule, at this epoch by far the 
 larger, remains uncovered by the integuments. 
 
 Both integuments grow longitudinally by constantly repeated 
 division of the crowns of cells at their summits, by walls alter- 
 nately inclined to and from the nucleus (fig. 19). The outer 
 integument soon acquires considerable thickness through two or 
 three repetitions of the division of the cells of the second degree, by 
 means of walls parallel to the free outer surface ; when the ovule 
 is fully developed, this coat is composed of lax tissue, traversed 
 by intercellular spaces full of air, enclosed by an epithelium 
 formed of cells one-fourth the size and filled with watery fluid. 
 The cells of the second degree of the inner integument, do not 
 become multiplied in the direction of the breadth until this coat 
 has grown up beyond the summit of the nucleus. Then, how- 
 ever, its upper margin rapidly becomes broader and thicker 
 through repeated division of the cells by means of walls parallel 
 to the long axis of the ovule ; the mouth closes in, leaving only 
 the narrow canal of the micropyle (PL VII. fig. 22) formed solely 
 by the inner integument ; the outer coat of the ovule, which comes 
 to a standstill when the inner begins to increase in size, becomes 
 grown over by the thickened margin of the micropyle. 
 
 At the epoch when the integuments reach the level of the 
 summit of the nucleus, the latter is composed of an axial row 
 consisting of a few, eight to ten cells, enclosed by a double layer 
 of cells. A simple layer of cells covers the upper extremity of 
 the axial string and forms the summit of the nucleus (fig. 19). 
 As in most young organs of vegetables, the cells forming the 
 free outer wall of its surface possess tolerable firmness, different 
 from the gelatinous consistence of the cell-walls in the interior. 
 
248 W. HOFMEISTER ON THE DEVELOPMENT OF ZOSTEBA. 
 
 The uppermost three cells of the row occupying the longitudinal 
 axis of the ovule are distinguishable from their neighbours, at a 
 very early period, by a larger size and greater concentration of 
 their contents ; this is particularly the case with the uppermost 
 of them, which gradually grows up to be the embryo-sac, while 
 the nucleus undergoes a profound change of structure by an active 
 multiplication of the cells, especially of those at its lower part. 
 
 The cells of the surface of the upper end of the nucleus are 
 divided by longitudinal and transverse septa perpendicular to 
 the outer walls ; the same division is repeated in the " daughter- 
 cells/' The increase of this cellular hood, in length and compass, 
 thus keeps pace at first with that of the cell growing into an 
 embryo-sac (fig. 20), enclosed by it. A little later begins a very 
 rapid multiplication of the cells of the lower part of the nucleus, 
 in all three directions. In the first place the axial cells divide 
 by perpendicular longitudinal walls; the newly-formed cells 
 again divide by longitudinal walls standing at right angles to 
 those last produced. Thus from this time the embryo-sac no 
 longer rests upon a simple row of cells, forming the axis of the 
 mass of cells below it, but on a column formed of double pairs 
 of cells, which cells become repeatedly divided by horizontal 
 walls (fig. 21). The multiplication of the cells of the two peri- 
 pherical layers of the nucleus, only weak just below the growing 
 embryo-sac, becomes greater proceeding towards the base, where 
 the hitherto cylindrical mass of cells soon becomes strongly 
 bulged out. The multiplication of cells still continues in this 
 region even after the ovule has attained its normal size, so that 
 at the epoch of fertilization this part of the nucleus is composed 
 of cells one-fourth the size of those lying close beneath the 
 embryo-sac. Finally, the cells of the periphery of the nucleus 
 all divide once oftener by longitudinal and transverse walls 
 than those in contact with them ; they thus appear one-half the 
 height and breadth of the latter. 
 
 During the further increase of size of the embryo-sac, the cells 
 surrounding it become gradually broken down and compressed. 
 The firmer, free, outer walls of the superficial cells are not attacked 
 by this softening and solution of the cellulose ; after the breaking 
 down of the inner tissue has advanced to a certain point, these 
 outer walls of the superficial cells form a homogeneous, connected 
 
W. HOFMEISTER ON THE DEVELOPMENT OF ZOSTERA. 249 
 
 membrane, transparent as glass, which encloses, as a sac, the 
 semi-fluid mass of primordial utricles set free by the solution of 
 the cell-coats (fig. 21). The large primordial cell in the centre of 
 this mucilaginous mass, the nascent embryo-sac, from this period 
 begins rapidly to displace the rest, which become by degrees 
 completely dissolved ; first of all those bounding it laterally, 
 while the cap of cells covering its summit persists for a short 
 time longer (fig. 21). The primary nucleus of the embryo-sac 
 is always still distinctly perceptible in its centre ; radiating 
 threads of granular mucilage pass out from it. Three newly- 
 formed, closely- crowded, globular cells show themselves in the 
 chalazal extremity, while at the micropyle end appear also the 
 now newly-formed nuclei of the germinal vesicles (fig. 21), as 
 three brighter, globular cavities, surrounded by dense granular 
 mucilage (the vesicles imbedded in. the protoplasm with more 
 transparent fluid contents). 
 
 After the primordial utricle of the embryo-sac has also dis- 
 placed that hollow conical layer of dissolving cells which covers 
 its micropyle end, it becomes closely applied upon the now free 
 enveloping membrane*. This adhesion is so intimate at the 
 micropyle end, that in all subsequent stages the enveloping 
 membrane seems at this point to have been secreted by the 
 primordial utricle of the embryo-sac. Further down, from the 
 region where the cavity enclosed by the inner integument and 
 lined by the enveloping membrane (of the nucleus) becomes 
 widened and expanded into a cylindrical form, the growth of the 
 primordial utricle in breadth is frequently restricted; it then 
 runs on as a slender cylinder in the axis of the wider. The 
 tubular space between the enveloping membrane of the nucleus 
 and the elongated primordial utricle of the embryo-sac is filled 
 with finely granular mucilage coloured deep brown by iodine, 
 probably the product of the solution of the liquefied peripherical 
 cells of the nucleus (PL VII. fig. 23). 
 
 These processes are accompanied by a very considerable elon- 
 gation of the embryo-sac and the enveloping membrane of the 
 nucleus, which both integuments follow by a rapid multiplica- 
 tion of their cells in the direction of the length of the ovule. 
 
 * Formed by the persistent, connected outer walls of the superficial layer of 
 cells of the nucleus (see above). A. H. 
 
250 W. HOFMEISTER ON THE DEVELOPMENT OF ZOSTERA. 
 
 The shape of the ovule becomes materially altered by this, passing 
 from an ovate form into that of a cylinder with a slightly at- 
 tenuated summit and a rather swollen base. 
 
 The lower persistent part of the nucleus is now pear-shaped. 
 Its apex, as in Crocus and elsewhere, exhibits a funnel-shaped 
 excavation, lined by the chalazal end of the embryo-sac, in which 
 are confined the three " enigmatical antipodes of the germinal 
 vesicles* 55 (fig. 23). The germinal vesicles themselves, now 
 fully developed, pear-shaped and large, with the inside of their 
 walls lined by a layer of protoplasm which encloses the now 
 lenticular nucleus, bear a similar relation to the micropyle end 
 of the embryo-sac (figs. 22-24). The primary nucleus of the 
 latter has by this time disappeared : if the embryo-sac has become 
 adherent at all points to the enveloping membrane of the nucleus, 
 secondary nuclei of a lenticular form are now frequently found 
 lying upon the inside of the wall of the former, and these are 
 mostly the centres of slightly developed systems of radiating 
 threads of granular mucilage (fig. 22). With the exclusion of 
 an exceptional case occasionally occurring in Z. minor, to be 
 mentioned hereafter, this is the only indication of a preparation 
 for the production of endosperm met with through the whole 
 existence of the ovule ofZostera. After fertilization these nuclei 
 disappear again, without having arrived even at a transitory 
 cell-formation. 
 
 The ovule is now ready for fertilization ; during its develop- 
 ment the mouth of the rudimentary ovary becomes prolonged 
 into the canal of the style ; the filiform stigmas spring out later 
 through a more active multiplication of cells at two points of 
 the circumference of the orifice. The styles, which turn up- 
 wards at obtuse angles, are protruded at the period of flowering 
 from the slits of the leaf-sheath enclosing the inflorescence. 
 The anthers burst at the same epoch ; each half-anther opens 
 by a longitudinal slit running up over the septum dividing the 
 two loculi. The filiform pollen-cells arrive immediately upon 
 the arms of the stigma projecting into the burst half-anthers. 
 They are often found, singly or several together, spirally wound 
 round these arms. 
 
 * A. Braun, Die Erscheinuny der Verjungung, &c. Leipsic, 1849 (1851), 
 p. 297. 
 
VV. HOFMEISTER ON THE DEVELOPMENT OF ZOSTERA. 251 
 
 The end of the pollen-cell penetrates into the canal of the 
 style opening at the summit of the two arms of the stigma. I 
 was unable to lay free, uninjured from the stigma to the micro- 
 pyle, the pollen-tube into which the otherwise already tubular 
 pollen-cell is doubtless converted by continued growth of one of 
 its extremities in the longitudinal direction. Within seven 
 hours after the dehiscence of the anther, the pollen-tube is found 
 in the cavity of the ovary * ; adhering closely to the outer side 
 of the pendent ovule, it grows down to its micropyle, into which 
 it penetrates, suddenly making a sharp curve. The internal 
 cavity of the ovary, now greatly enlarged by the expansion of 
 its \valls, is filled with transparent but tolerably firm jelly, in 
 which may sometimes be distinguished swollen-up cells, not un- 
 like those of the epithelium of the inside of the human mouth, 
 They are perhaps detached cells of the conducting tissue. A 
 little air-bubble is commonly found in the lower extremity of 
 the cavity of the ovary, at the end opposite to the stigma. 
 
 The pollen-tube is of the same diameter as the pollen-cell 
 (figs. 24-26). The portion outside the micropyle dies away 
 rapidly; within this it remains perceptible for a considerable 
 time. It does not usually penetrate farther than the summit 
 of the embryo-sac, very rarely insinuating itself for a short 
 distance down between this and the inner wall of the second 
 integument. 
 
 After the arrival of the end of the pollen-tube at the outer 
 wall of the embryo-sac, formed by the enveloping membrane of 
 the nucleus, one of the germinal vesicles increases in size and its 
 nucleus vanishes (fig. 24). The other germinal vesicles shrivel 
 up (fig. 25) and die away ; often even before the pollen-tube 
 has emerged from the micropyle-canal. A newly-formed, glo- 
 bular or ellipsoidal nucleus soon makes its appearance in the 
 lower end of the fertilized germinal vesicle, inside the mass of 
 protoplasm accumulating there ; immediately after this comes, 
 above the nucleus, a septum, convex on the upper side, dividing 
 
 * Anthers of a plant of Zostera marina taken from the sea-water on the 
 4th of June 1851, opened before my eyes on the 7th of June at half-past 6 in 
 the morning, after a land journey of more than forty hours. By one o'clock on 
 the same day the pollen-tubes had penetrated into the micropyles of ovules of 
 the same inflorescence. The plants had been kept ever since their removal from 
 their habitat moderately damp (not wet), and excluded from the air. 
 
252 W. HOFMEISTER ON THE DEVELOPMENT OF ZOSTERA. 
 
 the germinal vesicle into a small lenticular, lower cell, and a 
 larger, expanded, upper cell (fig. 25). The latter contains no 
 nucleus ; a thin layer of granular mucilage coats the inside of 
 its wall, and its cavity is filled with watery fluid. This upper 
 cell is not further developed during the subsequent completion 
 of the seed. 
 
 The little lower cell, on the contrary, at once enters upon a 
 very rapid multiplication. It swells up into a flattened globular 
 form, and divides by a longitudinal wall ; both the newly-formed 
 hemispherical cells then immediately divide into two " daughter- 
 cells/ 5 having the form of quarters of a sphere, by septa stand- 
 ing at right angles to those just before produced. These four 
 cells, constituting the rudiment of the embryo, are each divided 
 by a horizontal cross septum (fig. 26) . By continued halving 
 of its cells, principally in the longitudinal direction, the flat- 
 tened globular mass of cells (fig. 26) soon becomes spherical 
 (figs. 27, 28) ; and finally, while constantly increasing in size, 
 ovate and compressed laterally (fig. 29). The large spherical 
 cell which supports it is only loosely attached to the inside of 
 the wall of the micropyle end of the embryo-sac. I more 
 than once saw the swollen cell, and the cellular mass sprung 
 from it, slip from the micropyle end of the embryo-sac half- 
 way towards the other extremity, without perceptible external 
 cause*. 
 
 By the time the rudiment of the embryo has acquired the 
 globular form, a single apical cell becomes distinctly visible 
 (fig. 28), in the organ which in previous stages of development 
 undoubtedly possessed four. This transformation may be aptly 
 explained by the supposition that one of the four cells originally 
 forming the apex divides into one inner and two outer cells ; 
 either by a longitudinal septum forming an angle of 45 with 
 each of the two side walls of the cell, after which a radial lon- 
 gitudinal wall appears in the outer of the newly-formed cells ; 
 or by a longitudinal wall parallel to one of the lateral surfaces, 
 the formation of which is immediately followed by that of an- 
 other at right angles to it. If we further suppose that, in either 
 case, the other three of the previously apical cells become di- 
 vided by radial longitudinal septa, during the formation of one 
 
 * See the note to fig. 26 in the explanation of the figures. 
 
W. HOFMEISTER ON THE DEVELOPMENT OF ZOSTERA. 253 
 
 inner and two outer in the fourth cell, the final result, under 
 either hypothesis, would be the formation of a central (apical) 
 cell surrounded by a chaplet of eight cells. 
 
 During the transformation of the smaller segment of the im- 
 pregnated germinal vesicle into a globular cellular body, the 
 enveloping membrane of the nucleus, which has become a tough 
 coat of the embryo-sac, adheres most intimately to the inside of 
 the inner integument. The edges of contact of the cells of the 
 latter soon make marks upon the hitherto homogeneous, smooth 
 membrane in the form of cellulose ridges running upon it ; at 
 first extremely delicate, scarcely perceptible, but gradually more 
 distinct, and at last so sharp, that the wall of the embryo-sac 
 most deceptively resembles, when seen only on the surface, a 
 layer of tubular cells filled with transparent contents. The pe- 
 culiar conditions of this enveloping membrane, its lengthened 
 vital activity, its energetic growth, and its nutrition by the 
 tissues and cells of different kinds which it encloses, deserve 
 particular attention. 
 
 From one of the broad surfaces of the laterally-compressed, 
 ovate rudiment of the embryo springs an obtusely conical pro- 
 jection of cellular tissue, the rudiment of the future principal 
 axis of Zostera, which is thus a secondary axis, a lateral sprout 
 of the leafless axis of the first rank, of the embryo. Very soon 
 after the appearance of the new structure, the first leaf is deve- 
 loped, a little below its apex (figs. 30, 31, 33-35). This presents 
 itself as a little ridge nearly surrounding the end of the stem, 
 and very rapidly grows higher at the border turned to the cha- 
 laza, than at other parts. The leaf grows longitudinally through 
 constant repetition of the division of a transverse row of apical 
 cells, by walls inclined alternately towards the upper and lower 
 surfaces of the leaf, and by division of the cells of the second 
 degree by cross walls. The direction of its growth is parallel to 
 the primary axis of the embryo, diverging at right angles from 
 its parent axis. 
 
 During the development of this leaf, a very considerable alter- 
 ation occurs in the shape of that axis of the first rank : by active 
 multiplication of its cells, predominantly in the directions of 
 breadth and length, the ellipsoidal cellular body becomes a flat 
 mass truncated below and gradually attenuated toward the upper 
 
254 W. HOPMEISTER ON THE DEVELOPMENT OF ZOSTERA. 
 
 and lateral borders (PL VIII. figs. 32, 35-3?). The lateral borders 
 at the same time curve over the anterior surface, so that they finally 
 enclose, like a hood, the secondary leaf-bearing axis attached 
 upon that surface. The multiplication of the cells, very active 
 at all the edges of the cellular plate, lasts longest at the upper 
 margin, directed towards the micropyle. The large cell, to which 
 the embryo was previously suspended, becomes pushed very 
 much to one side by this (fig. 32). Soon compressed by the 
 further increase of size of the primary axis, it is in a short time 
 lost sight of altogether. 
 
 The leaf-bearing axis, the lower, naked portion of which 
 has meantime been extending upward with a considerable cur- 
 vature, unfolds, soon after the protrusion of the first leaf, the se- 
 cond, opposite to that ; the third becomes opposed to this higher 
 up on the stem, and finally the fourth to the third (fig. 39). The 
 greatly prolonged extremity of the stem grows by continued 
 repetition of division of the single apical cell, by means of septa 
 inclined alternately to the two surfaces of the leaf, division of 
 the cells of the second degree by radial longitudinal walls, and 
 so on ; corresponding to the rule of cell-multiplication in the 
 rudiment of the fruit of Mosses, of the Marchantiece, the stem 
 of Mosses, the stem of 'the Polypodiaceae, the axes of the 
 Equisetaceae and Pilulariete, and the young embryos of the 
 Coniferae. But, as in the Coniferae, the rule of cell-formation 
 changes subsequently, after the germination of the seed. The 
 one apical cell of the now obtuse, flattened terminal bud (fig. 40) 
 divides by walls inclined successively to the four points of the 
 compass, in agreement with the rule of cell-multiplication in the 
 further developed rudiment of the fruit of Anthoceros*. 
 
 Buds appear in the axils of the older leaves even before the 
 maturity of the embryo. Subsequently also, in the fully-deve- 
 loped, annual sterile plant, the formation of an axillary bud 
 follows that of the leaf almost immediately (PL VIII. fig. 40). 
 
 In the foregoing I have called the cellular body, formed by 
 the increase of the lower segment of the impregnated germinal 
 vesicle, which is finally transformed into a hood-shaped layer of 
 cellular tissue, the axis of the first rank, of the embryo. Older 
 botanists regarded it as the cotyledonary leaf, a view which 
 
 * See page 6 of my Fergleichende Untersuchungen, &c. Leipsic, 1851. 
 
W. HOFMEISTER ON THE DEVELOPMENT OF ZOSTERA. 255 
 
 Gronland also supports, although A. de Jussieu*, so long ago 
 as 1838, demonstrated that this is untenable, by comparison 
 with other Monocotyledonous embryos, and explained the organ 
 as a transformation of the plumule (tigelle) of the embryo, with- 
 out however recognizing the leaf-bearing stem as a secondary 
 axis. An unprejudiced examination of the course of develop- 
 ment completely refutes the older view. But even if it were 
 assumed, for the sake of the pretended analogies, that the direc- 
 tion of the main axis of the embryo underwent a division not to 
 be detected by actual observation ; that the cell of the lateral 
 surface of the flattened -ovate cellular body, which gives origin 
 by its cell -multiplication to the leaf-bearing axis, was the twelfth 
 cell of the first degree of the embryo, and that the obtuse end of 
 that cellular mass underneath this cell was the rudiment of the 
 cotyledon, the cotyledon and the next succeeding leaf would 
 be made to stand in one perpendicular line, i. e. the leaf directly 
 over the cotyledon ; a supposition incompatible with the phaeno- 
 mena exhibited in the after-life of Zostera. 
 
 There is no example among all the Dicotyledons of the 
 principal leaf-bearing stem of a plant being an axis of the second 
 rank, the lateral sprout of a leafless primary axis. The develop- 
 ment of the embryo of Tropceolum, which at first sight appears 
 similar to that of Zostera, differs from it most essentially in the 
 circumstance that the portion of the pro-embryo, from the end- 
 cell of which the embryo originates, is in Tropceolum the primary 
 axis, only crowded to one side by the more vigorous development 
 of the peculiar lateral sprout of the pro-embryo f. 
 
 Among the Monocotyledons there is one plant, Ruppia 
 rostellata, resembling Zostera in many characters of its sub- 
 sequent life, which may be compared with the latter, in reference 
 to the characters of the embryo, without straining any point. 
 The ovule of Ruppia agrees in structure with that of Poiamogeton. 
 Like that, it completely resembles the ovule of Zostera in its 
 early development, in attachment, direction and shape (fig.41 a,b}. 
 But that large cell in the interior which becomes the embryo-sac, 
 only displaces a moderate portion of the nucleus before impreg- 
 nation ; the outer layers of cells of the latter persist (fig. 42). As 
 inPotamoaeton, the previously concentrically-shaped ovule begins 
 
 * Ann. des Sc. Nat. 2 ser., Botanique, torn. xi. 
 f See my essay Die En$tehung des Embryo. 
 
256 W. HOFMEISTER ON THE DEVELOPMENT OF ZOSTER A 
 
 to assume a symmetrical form shortly before impregnation. The 
 micropyle becomes pushed downwards by active multiplication 
 of the cells on its outer side, turned away from the contiguous 
 angles of the four ovaries (fig. 42). A multiplication of the cells 
 of the opposite side of the nucleus commencing at the epoch of 
 impregnation, subsequently pushes the micropyle upwards again 
 with a great curvature of the entire ovule (fig. 43). The integu- 
 ments follow the increasing size and changing shape of the ovule by 
 multiplication of their cells in the directions of length and breadth. 
 After impregnation the process of multiplication and expansion 
 of the cells becomes very unequal, especially on the inner coat 
 of the ovule : much more active in the lower than in the upper 
 half, it pushes the endostome still farther upward (fig. 44), and 
 removes it from the endostome, which remains nearer its original 
 place, and consequently becomes diverted to the side. 
 
 The impregnated germinal vesicle of Ruppia divides, as in 
 Zostera and Potamogeton, into a larger, upper, persistent cell and 
 a smaller, inferior cell which undergoes rapid multiplication. 
 During the gradual removal of the papilla (apex) of the nucleus 
 and of the endostome from the place of the germinal vesicle, the 
 pollen-tube, which remains outside the membrane of the embryo- 
 sac, extends itself, inside the place where it penetrates, through 
 the apex of the nucleus, by means of considerable longitudinal 
 growth of its tough membrane (fig. 43 b). 
 
 The lower segment of the impregnated germinal vesicle very 
 soon becomes changed, by a series of longitudinal and transverse 
 divisions (figs. 43 b, 44 b), into a globular and subsequently an 
 ovate cellular body (fig. 45 b), from the side of which, below the 
 apex, shoots forth the first leaf-bearing axis. It unfolds its first 
 leaf close above its point of origin. After the imbedding of the 
 base of the leaf-bearing axis in the thick, fleshy, primary axis, 
 the first adventitious root grows out, in germination, opposite 
 the lamina of that first leaf (the cotyledon), forming a right angle 
 with the line of direction of the leaf. The margins of that lateral 
 face of the primary leafless axis which bears the leafy secondary 
 axis, rise up into a kind of -collar, enclosing the base of the 
 latter as a short, widely opened sheath (fig. 46). 
 
 Irmisch*, in a clear explanation of the subsequent course of the 
 
 * " On the Inflorescences of the German Potame<s," Flora 1851, p. 81 et seq. 
 
W. HOFMEISTER ON THE DEVELOPMENT OF ZOSTERA. 257 
 
 germination of Ruppia, has already drawn particular notice to 
 the fact, that the germination not only of Potamogeton, but of 
 all the grasses in which the first leaf stands before the scutellum, 
 agrees in the main points with that of Zostera. The history of 
 development of these embryos, far from weakening the founda- 
 tion for such an interpretation of the individual parts, rather 
 speaks more distinctly in favour of the so-called scutellum of the 
 embryos ofZea and Sorghum being analogous to the first, leafless 
 axis of Zostera *. 
 
 The course of development of the embryo of other Mono- 
 cotyledons, so far as known, gives still further probability to the 
 idea that the "cotyledon 55 is an axis with limited growth, from 
 the side of which breaks forth a sprout, the future leaf-bearing 
 main axis of the plant. I refer to the history of development of 
 the embryo of Canna^ given by Jussieu, with which completely 
 agree, besides those of the plants mentioned by Jussieu himself, 
 those of Hyacinthus comosus, Funkia cterulea, Fritillaria impe- 
 rialis and other Liliaceae, that of Iris and others. In all cases 
 the first cell of the embryo (the lowest cell of the pro-embryo 
 forming the suspensor) becomes converted by a series of divisions 
 into a globular, ovate or spindle-shaped cellular body, the in- 
 crease of thickness of which is arrested at a point below the 
 summit. Thus is formed a lateral, more or less deep slit, from 
 the bottom of which is developed the plumule, in one case (Fri- 
 tillaria) not till after germination. No fact is less available as 
 testimony against the axial nature of the so-called cotyledon of 
 the Monocotyledons, than that of its base enclosing the plumule 
 as a sheath. If the secondary axis originates at a point on the 
 primary in which the growth in thickness of this latter is arrested 
 some time before the appearance of the lateral sprout, the en- 
 compassing of the new axis by the thickened borders of the 
 
 * See figures 1 2-1 4, 32-34 of PI. xi. of my Essay Die Enstehung des Embryo 
 der Phanerogamen. At the time when I published those researches, not yet 
 enlightened by the study of the formation of the embryo of the Naiadese, I 
 thought myself obliged to adhere to the view advocated by Bernhardi, Schleiden 
 and Jussieu, although it did no little violence to the phaenomena observed. The 
 papilla of cellular tissue becoming the plumule, appears from the first distinctly 
 lateral and below the apex of the nascent " cotyledon," in these grasses, as also 
 in the Avenacece and Trificeee. 
 
 t Loc. cit. p. 348. 
 
 SCIEN. MEM. Nat. Hist. VOL. I. PART III. 17 
 
258 W. HOFMEISTER ON THE DEVELOPMENT OF ZOSTEBA. 
 
 lateral surface of the older sprout naturally follows ; as occurs 
 most clearly in the earliest rudiments of fronds, situated in de- 
 pressions of the creeping main axis, of Polypodium aureum and 
 other Ferns. But even secondary axes which become nakedly 
 visible on the originally convex outer surface of the young main 
 axis, may likewise become sheathed subsequently by the primary 
 sprout, through peculiar growth of the latter ; Isolepis affords a 
 striking proof of this. 
 
 It need scarcely be explained that the discussion here promul- 
 gated is not and could not be anything more than an invitation 
 to repeated investigations of the different stages of development 
 of the Monocotyledonous embryo. A complete decision in 
 favour of one or other of the two views can only be obtained by 
 tracing back a difficult task indeed the development of the 
 seedling plant to the mode of increase of each individual cell. 
 
 No question in the whole field of the Morphology of Plants 
 has been treated by so many persons and in such varied ways, 
 as the import of the parts of the embryo of the Monocotyle- 
 dons ; to none better applies an often misplaced quotation from 
 Goethe ; we may assert that " all possible combinations are ex- 
 hausted " here. Thus the idea brought forward in the foregoing 
 pages is only the repetition of an earlier one essentially similar. 
 If it be thought better grounded than that more current among 
 modern botanists, we find, in recompense for the wide separation 
 it makes between the Dicotyledons and Monocotyledons, the 
 most striking agreement of the development of the embryo of 
 the latter, with the course of the formation of the germling of 
 the Vascular Cryptogamia. As I have abundantly demon- 
 strated*, the main stem of the plant of all Vascular Cryptogams 
 is a secondary axis, arising laterally on the primary leafless 
 axis. A second and not unimportant point of comparison then 
 at once suggests itself. The Vascular Cryptogams may be 
 divided into two primary groups according as the germinating 
 plant produces the second frond below the first (below that sur- 
 face turned away from the mouth of the archegonium), or above 
 it. In the former case the first adventitious root appears simul- 
 taneously with the first frond, beside its base ; in the latter case, 
 
 * See Botanische Zeitung, \ 849, p. 797 ; " Vergleichende Untersuchungen, 
 Sec." Leipsic, 1851, pp. 85, 106, and elsewhere. 
 
W. HOFMEISTER ON THE DEVELOPMENT OP ZOSTERA. 259 
 
 opposite to it. The Ferns and Rhizocarpeae belong to the first 
 of these sections, Selaginella and Isoetes to the second. The 
 peculiar arrangement of the roots of Isoetes does not follow so 
 much from the condition just indicated, as from the phenomena 
 of the growth of the mantle of cambium, annually renewing the 
 cortical tissue, surrounding the wood-structure ; combined with 
 the suppression of the internodes. In Zostera, Ruppia, and in 
 the Grasses, the mode of appearance of the first adventitious 
 root is the same as in Isoetes. It springs out opposite the first 
 leaf, not behind it. The great majority of the Monocotyledons 
 seem to behave in the same way. In Lemna, on the contrary, 
 the position of the first adventitious root corresponds to that of 
 the Ferns. To carry through the comparison of the two classes 
 in this respect will require still more comprehensive researches. 
 
 EXPLANATION OF PLATES VI, VII and VIII. 
 
 Fig. 1. Longitudinal section of the terminal bud of a fertile plant of Zostera 
 minor, magnified 30 diam. : a the third, b the second, c the first 
 (youngest) spadix ; a 1 , 6 1 , c l , the sheathing basal leaves (niederbldtter) 
 of the sprouts terminating as spadices; a 2 , 6 2 , c 2 , the stem-leaves 
 (laub-blatter) of the same ; d, the new sprout arising in the axil of 
 the sheathing leaf of the youngest sprout. 
 
 Fig. 2. A similar preparation of Zostera minor. The section, not carried 
 quite accurately through the slit of the sheathing leaf of the sprout of 
 the penultimate rank, has hit the overspreading part of this sheath. 
 
 Fig. 3. Apex of a spadix of Z. marina commencing a longitudinal develop- 
 ment, seen from above. Magnified 40 diam. : a, anthers ; b, ovaries. 
 
 Fig. 4. Young anther (a) and rudiment of an ovary (b) of Zostera minor, seen 
 from above. Magnified 120 diam. 
 
 Fig. 5. Transverse section of a very young half-anther of Z. minor. Only the 
 contents of the primary parent-cell of the pollen represented. Magn. 
 350 diam. 
 
 Fig. 6. Similar preparation from a somewhat more developed anther. Magn. 
 350 diam. 
 
 Fig. 7. Some of the primary parent- cells of the pollen, from the longitudinal 
 section of a very young half-anther of Z. marina. Magn. 400 diam. 
 
 Fig. 8. Lower portion of a longitudinal section of a half-anther of Z. marina, 
 parallel to the surface of the spadix ; a, cells of the septum between 
 the two loculi. Some of the elongated parent-cells of the pollen 
 cut across. Magn. 400 diam. 
 
 Fig. 9. Portion of the longitudinal section of a half-anther of Z. marina imme- 
 diately after the formation of the pollen-cells. Magn. 400 diam. 
 
 17* 
 
260 W. HOFMEISTER ON THE DEVELOPMENT OF ZOSTERA. 
 
 Fig. 10, 12, Transverse sections of loculi of somewhat more developed anthers 
 of Z. minor. Magn. 200 diam. 
 
 Fig. 1 1 . A collection of young pollen-cells of Z. marina. Magn. 400 diam. 
 
 Fig. 13. A few somewhat further developed pollen-cells of the same species, 
 isolated in concentrated solution of carbonate of ammonia. Magn. 
 400 diam. 
 
 Fig. 14. Longitudinal section of the lower part of an anther-loculus of Z. minor. 
 Magn. 300 diam. 
 
 Fig. 15. Piece of a mature pollen-cell of Z. marina. The ascending current of 
 protoplasm is shown darker, the descending lighter. Magn. 400 diam. 
 
 Fig. l'5 b. Pieces of mature pollen-cells exhibiting protrusions of all kinds (see 
 page 245). Magn. 200 diam. 
 
 Fig. 16. Very young ovaries of Z. marina, seen from above; a, rudiment of 
 the ovule. Magn. 300 diam. 
 
 Fig. 17, 18. Subsequent stages of development of the ovary, in longitudinal 
 sections. Magn. 100 diam. 
 
 Fig. 19. Ovules and the surrounding parts of the walls of the ovary, in longi- 
 tudinal section. Magn. 320 diam. The pendent ovule is here re- 
 presented reversed and upright, as in all the succeeding figures. 
 
 Fig. 20, 21. Longitudinal sections of the nuclei of more developed ovules. 
 Magn. 300 diam. 
 
 Fig. 22. Longitudinal section of an ovule ready for impregnation. The for- 
 mation of the cells compressed into the chalazal end of the embryo- 
 sac has not taken place here. Magn. 320 diam. 
 
 Fig. 23. Longitudinal section of an ovule of the same species ripe for impreg- 
 nation. Magn. 180 diam. 
 
 Fig. 24. Micropyle and upper end of the embryo-sac of an ovule in longitudinal 
 section, at the moment when the pollen-tube has penetrated to the 
 membrane of the sac. Magn. 300 diam. 
 
 Fig. 25. A similar preparation, a little later, with the impregnated germinal 
 vesicle divided into an upper, large -suspensor cell, and a lower, small 
 embryonal cell. Mag. 300 diam. 
 
 Fig. 26. A similar preparation with the embryonal globule, composed of 16 cells, 
 represented in longitudinal section. During the observation the 
 suspensor and the embryonal globule slipped from the micropyle end 
 of the embryo-sac as far as *, without perceptible external cause. 
 Magn. 300 diam. 
 
 Fig. 27. Lateral view of a further developed embryonal globule with the 
 suspensor. Magn. 400 diam. 
 
 Fig. 28. A similar embryonal globule, in longitudinal section, at right angles 
 to the projection of the preceding figure. Magn. 400 diam. 
 
 Fig. 29. Front view of an embryo with suspensor of Z. minor, shortly before 
 the origin of the leaf-bearing axis. Magn. 60 diam. 
 
 Fig. 30. Lateral view, 60 diam. ; fig. 31. front view, of farther developed em- 
 bryos of the same species. Magn. 40 diam. 
 
 Fig. 32. Lateral view of the embryo of a half-ripe seed of the same species. 
 The outline of the secondary axis is indicated by delicate lines, show- 
 ing through the lateral wing of the primary axis. Magn. 40 diam. 
 
W. HOFMEISTER ON THE DEVELOPMENT OF ZOSTEBA. 261 
 
 Fig. 33-35. Embryos of Z. marina. Fig. 33, side view of a young embryo 
 fig. 34, front view of one somewhat older ; fig. 35, seen obliquely 
 from behind. Magn. 40 cliam. 
 
 Fig. 36. Longitudinal section of a half-developed embryo. Magn. 30 diam. 
 
 Fig. 37. Longitudinal section of an almost ripe embryo. Magn. 30 diam. 
 
 Fig. 38. Ripe embryo, in front, back and lateral views. Magn. 4 diam. 
 
 Fig. 39. Longitudinal section of the bud of an almost ripe embryo. Magn. 60 
 diam. 
 
 Fig. 39 b. The end of the stem of the same. Magn. 300 diam. 
 
 Fig. 40. Longitudinal section of the terminal bud of a sterile plant of Z. marina. 
 
 Fig. 41-46. Ruppia rostellata. 
 
 Fig. 41 . Longitudinal section of a young ovary. Magn. 40 diam. 
 
 Fig. 41 b. The ovule of the same. Magn. 200 diam. 
 
 Fig. 42. Longitudinal section of an ovule ready for fertilization. Magn. 60 diam. 
 
 Fig. 42 b. Embryo-sac of the same. Magn. 300 diam. 
 
 Fig. 43. Longitudinal section of an ovule immediately after impregnation. 
 Magn. 40 diam. 
 
 Fig. 43 b. Endostome, papilla of the nucleus and micropyle-end of the embryo- 
 sac of the same. Magn. 300 diam. 
 
 Fig. 44. Longitudinal section of an ovary, some eight days after fertilization. 
 Magn. 30 diam. 
 
 Fig. 44 b. The rudimentary embryo of the same. Magn. 200 diam. 
 
 Fig. 45. Longitudinal section of a farther developed ovary. Magn. 30 times. 
 
 Fig. 45 b. The embryo from it. Magn. 200 diam. 
 
 Fig. 46. Longitudinal section of an almost ripe embryo. Magn. 40 diam. 
 
 [A. H.] 
 
262 M. WICHURA ON THE WINDING OF LEAVES. 
 
 ARTICLE IX. 
 On the Winding of Leaves. By M. WICHURA. 
 
 [From the 'Flora,' January and February 1852.] 
 
 THE leaves of plants possess in the flexibility of their tissue 
 full capability of twisting, and it has long been known that this 
 property must often serve to assist the efforts of plants to ap- 
 proach towards the light. Twisting movements of this kind are 
 readily recognizable from the circumstance that all the characters 
 of the movement may be brought into agreement with their pur- 
 pose, to direct the upper face of the leaf towards the light. The 
 twisting begins directly anything turns the upper face of the 
 leaf away from the light, and continues until that face is again 
 directed to the full rays of the incident light. It turns indif- 
 ferently either to the right or left, according to which path will 
 lead quickest to its object. Its extreme degree never exceeds 
 a half-revolution, since this suffices to turn the leaf completely 
 over, and therefore to return the upper side again towards the 
 light, when it has been wholly turned away from it. 
 
 But there are plants the winding leaves of which present ex- 
 actly the opposite character in all these things, and, in particu- 
 lar, exhibit the same regularity in their lateral direction as we 
 detect in winding stems. 
 
 The winding movements of the second kind cannot be re- 
 garded as an effect of the irritability of vegetable tissue excited 
 by light. They are immediate expressions of the vital force ac- 
 tive in the interior of the plant, and nearly allied to the winding 
 of the stem and tendrils. While, however, the latter have long 
 occupied the attention of botanists, the windings of leaves have 
 remained almost unknown, and all that we possess are a few- 
 scattered and mostly very meagre notices thereon. I myself 
 gained my first knowledge of them through perceiving the 
 heliacal winding of the leaves and strict regularity displayed in 
 their direction, in some Oat and Barley plants germinating in- 
 doors. Further researches, to which I was thereby attracted, 
 
M. WICHUBA ON THE WINDING OF LEAVES. 263 
 
 made partly in the field, partly in the Botanical Gardens of 
 Breslau and Berlin, and lastly, partly in the General Herbarium 
 at Berlin, have revealed to me so great a number of similar 
 phaenomena, that I venture to found upon them an attempt at a 
 general description of the phenomenon. 
 
 I. Form and outward condition of Winding Leaves. 
 
 1. 
 
 Although examples of winding leaves may be pointed out in 
 all metamorphoses of the leaf, in the most diverse families of 
 the vegetable kingdom, and in all the local floras of the globe, 
 much agreement in structure is exhibited by them in spite of 
 this wide diffusion. They are all of longish, mostly linear- 
 lanceolate shape, have smooth entire margins, and in regard to 
 the distribution of their vascular bundles, either belong to the 
 parallel-nerved system, as developed most clearly in the stem- 
 leaves of Monocotyledons, or they are totally devoid of vessels, 
 as in the leaves of the Mosses and Liver-worts. The angular- 
 nerved leaves of the Dicotyledons, as for instance of our fruit- 
 trees, of the Poplar, Lime, &c., appear never to admit this 
 winding movement. In the Dicotyledons only those leaves 
 wind which imitate, either perfectly or at least approximative^, 
 the parallel-nerved .system of the Monocotyledons. 
 
 2. 
 
 If we attempt to bring the properties of winding leaves, men- 
 tioned in the preceding section, under a common point of view, 
 we must say that the longitudinal growth is developed at the 
 cost of the transverse growth in winding leaves. For, if the 
 angular-nerved distribution of the veins in which strong branches 
 turn off toward both sides from the midst of the leaf, and, sud- 
 denly leaving the longitudinal direction, pass into the transverse, 
 is to be considered, no less than the lateral subdivision of the 
 leaf into teeth, pinnae, &c., as the expression of an active growth 
 in the direction of the breadth, it follows that the essential 
 feature of leaves which neither have an angular venation, 
 nor are toothed or pinnate, but are parallel-veined, smooth- 
 edged and very narrow in proportion to their length, must be a 
 
264 M. WICHURA ON THE WINDING OF LEAVES. 
 
 deficiency of transverse and an excess of longitudinal growth. 
 Winding leaves agree perfectly in this respect with winding 
 stems and tendrils, the thread- or string-like shape of which at 
 once reveals the predominance of longitudinal growth. 
 
 3. 
 
 Another peculiarity of winding leaves might be sought in the 
 distribution of their stomates,, In the ordinary, not winding 
 leaf, they are chiefly placed on the lower face, next the ground, 
 in order, as is supposed, to come, in this way, into immediate 
 and close contact with the gases and vapours ascending from 
 beneath. A differently contrived distribution of the stomates 
 should consequently be provided for winding leaves, which by 
 their curvature often change the relative position of their two 
 faces toward the vicinity. This conjecture finds a very striking 
 confirmation in the stem-leaves of the Alstrwmerice, which turn 
 quite over by a half-revolution, for, according to the beautiful 
 observations of Lindley, these bear the stomates, contrary to the 
 ordinary rule, on the upper face, turned towards the ground 
 only by the twisting. The winding leaves of the Grasses also, 
 as I have had an opportunity of observing, present anomalies, 
 in so far that they are furnished with stomates almost equally 
 on both sides of the leaf. Unfortunately I was unable to extend 
 these somewhat e time-devouring 3 researches to other families. 
 I can therefore only offer a conjecture that winding leaves are 
 distinguished from those not winding by a more or less aberrant 
 distribution of the stomates. 
 
 4. 
 
 In other respects, winding leaves present little that is striking 
 in their external appearance. Not twining round a support like 
 winding stems, they complete their curvatures in the free air, 
 and from their slender, linear form, one is at first sight inclined 
 to ascribe their curvature to accidental effects of the wind and 
 of desiccation. The detection of the regularity prevailing in 
 their direction unfolds the error of the supposition, and opens 
 to our view a rich and everywhere ready field of observation, 
 where we previously passed by in indifference. 
 
M. WICHURA ON THE WINDING OF LEAVES. 265 
 
 II. Laws of Distribution. 
 
 5. 
 
 The relation of the winding to the outer form of the leaf, 
 mentioned in section I, gives the key to the laws of distribution 
 of the phenomenon. All alterations in the form of the leaf 
 connected with the proportion of the longitudinal to the trans- 
 verse growth, are consequently of importance in regard to the 
 occurrence of the winding movement. 
 
 6. 
 
 Even the single leaf displays changes of shape of this kind, 
 in its triple division into sheath, stalk, and blade. Winding 
 occurring in one of these parts is not therefore necessarily 
 imparted to the others, but is mostly limited within this. There 
 are many leaves with wound petioles and straight laminae, while, 
 on the contrary, in the stamens of Erythraea and other plants, 
 the lamina metamorphosed into an anther winds, while the 
 petiole, i. e. the filament, remains straight. Even within the 
 lamina itself, modifications of the curving movement occur, with 
 the expansions and contractions advancing from below upwards. 
 In such cases only the narrow parts wind, the broader not. 
 The broad ovate leaves of Paris quadrifolia, L., may be men- 
 tioned as an example, being straight as far as the attenuated 
 points which are wound slightly to the left. Leaves which 
 wind uniformly throughout their whole extent, exhibit the 
 corresponding perfect equality of transverse growth, from bottom 
 to top, as for instance the leaves of Typha latifolia, L., T. an- 
 gustifolia, L., and of many other Monocotyledons. 
 
 7. 
 
 The distribution of the winding movement in the different 
 leaves of the same axis depends on the same principles. Here 
 it is the metamorphoses of the leaf, known under the names of 
 cotyledons, stem-leaves, sepals, &c., which limit the winding 
 movement in virtue of their frequently totally different shapes. 
 It very frequently happens that the winding of the leaves is 
 
266 M. WICIIURA ON THE WINDING OF LEAVES. 
 
 confined to a single metamorphosis, or that when the leaves of 
 several metamorphoses wind, the intervening metamorphoses 
 which do not wind, are separated from each other. In many 
 species of Dianthus, for instance, the stem-leaves, the petals 
 and the styles wind. Between these lie the metamorphoses of 
 sepals and stamens, which do not betray a trace of the wind- 
 ing movement. 
 
 Winding and straight leaves are found united, even within 
 the single metamorphosis, when the form of the leaves belonging 
 to this metamorphosis is essentially altered from below upward, 
 or according to the position which they occupy on the axis. 
 Thus, for example, in Papyrus antiquorum, Willd., the lower, 
 rather broad stem-leaves do not wind, but the upper narrow 
 linear leaves preceding the inflorescence as bracts do. In many 
 irregular flowers likewise, only single leaves, mostly outwardly 
 conspicuous for prominent longitudinal growth, exhibit winding, 
 for example the labellum of Himantoglossum hircinum, Rich. 
 Here belong, moreover, the so-called oblique flowers, e.g. oflfys- 
 sopus lophanthus, L., Pedicularis palustris, L., &c., the oblique 
 shapes of which arise from particular organs only of the flowers 
 curving, and thus destroying the symmetry of the whole. 
 Finally, the twisted awns of the Grasses must also be mentioned 
 here, since in all cases they occur only in one of the paleae 
 forming the floral envelopes. 
 
 8. 
 
 The distinction in the shape of leaves belonging to relatively 
 like metamorphoses of different individuals, is fixed by the 
 systematic distinctions in the vegetable kingdom. The more 
 widely two species stand apart, systematically, the larger is the 
 sphere of possible differences in the development of the leaf, the 
 smaller therefore becomes the probability that they will behave 
 similarly in reference to the movement of winding. The divisions 
 into Cellular and Vascular Plants, Monocotyledons and Dicoty- 
 ledons, founded on the most general distinctions in the vegetable 
 kingdom, are consequently of no particular value for our purpose, 
 since each of these divisions includes formations of leaves ot the 
 most varied kinds. It can only be said that the stem-leaves of 
 
M. WICHURA ON THE WINDING OF LEAVES. 267 
 
 the Monocotyledons occur wound much more frequently than 
 the stem-leaves of the Dicotyledons, on account of their structure 
 being peculiarly suited for the movement of winding. 
 
 9. 
 
 It is only when we come to the families of plants that it be- 
 comes possible to sketch out general characteristics of the natural 
 divisions, in reference to the movement of winding. There are 
 families in which I have not hitherto detected a single example 
 of a winding movement, as for instance the Umbelliferae and 
 Cruciferae ; families in which the winding is confined to particular 
 genera or species, as in the Composite and Papilionaceae ; and, 
 finally, families in which the curvature of the leaves is typical, 
 as in the Ebenaceae, Apocynaceae and Asclepiadaceae. 
 
 The same holds good of the genera, with the distinction that 
 a complete agreement of the species included in them is much 
 more frequent than in the families. 
 
 In general, the behaviour of the individuals belonging to the 
 same species is identical. Deviations are rare, and seem only 
 to arise when the shape of the leaves has undergone a material 
 change through the influence of the station. Thus I found in a 
 hot-house a specimen of Hyacinthus orientalis, raised in rich 
 earth, in which the stem-leaves had attained the unusual length 
 of 2 \ feet, and were twisted, while under ordinary circumstances 
 the leaves of this plant do not wind. 
 
 10. 
 
 Finally, peculiarities of the soil and climate also have to be 
 mentioned among the causes of the diffusion of the phenomenon, 
 since these sometimes give a particular character to the habit of 
 the plant, and especially to the prevailing form of the stem- 
 leaves. Thus, tropical America is remarkable for an abundance 
 of plants with broad leaves with reticular venation, in which the 
 here incompatible movement of winding withdraws from notice, 
 and, considered in relation to other regional floras, becomes rare. 
 On the other hand, the floras of New Holland and the Cape of 
 Good Hope contain principally plants with narrow, parallel- 
 nerved stem-leaves, and it is to be regarded as a consequence of 
 this, that Dicotyledonous plants with winding stem-leaves occur 
 
268 M. WICHURA ON THE WINDING OF LEAVES. 
 
 comparatively much more frequently in these two regions than 
 in the other parts of the globe. 
 
 III. Single and associated Winding Leaves. 
 
 n. 
 
 The phenomenon of winding is not confined to the single 
 leaves of plants, but appears also in structures arising from the 
 confluence of several leaves. Longish shape and parallel course 
 of the vascular bundles are also conditions here. For example, 
 the tubes of the corollas of several Stylideae, which may be called 
 rather long in proportion to their diameter, those of Trifolium 
 resupinatum, L., and certain species of Peristrophe and Hy poesies 
 of the family of Acanthaceae. So, moreover, the elongated 
 buds of the Convolvulaceae and of Thevetia neriifolia, Juss. 
 (Apocynacere), originally composed of five separate and very 
 narrow segments, are folded toward one side like a closed um- 
 brella and curved spirally toward the other, &c. If the view, 
 now continually gaining ground, that the stem is not an inde- 
 pendent organ, but originates from the confluence of the 
 sheathing portions of the leaves fitted into each other, could be 
 regarded as completely demonstrated, the winding stem also 
 would have to be included here. 
 
 12. 
 
 After these examples of winding of several confluent leaves, 
 we may come to those which certainly wind separately, but are 
 situated so close together that they come in contact in the move- 
 ment of winding, and in this way enter into certain combina- 
 tions, which, from the regularity of the movement on which 
 they depend, assume a regular shape. 
 
 13. 
 
 Here belong : the entwined cotyledons of the Gyrocarpeas ; the 
 awns of the panicles of Streblochate nutans, Hochst., and Andro- 
 pogon Allioniiy D.C., which are twisted together into a cord-like 
 body ; the floral envelopes of many species of Iris and all the 
 species of Aristea (Iridaceae) known to me, which wind round 
 
M. WICHURA ON THE WINDING OF LEAVES. 269 
 
 spirally as the flower withers ; and lastly, what is called the 
 " contorted aestivation." The latter deserves a separate discus- 
 sion, because its connection with the winding movement is not 
 at first sight clear. 
 
 The " aestivatio contorta " is a structure which makes its ap- 
 pearance at a comparatively late stage of the growth of the bud. 
 When examined in their earliest conditions the rolled buds ex- 
 hibit leaflets standing singly, so narrow that their margins do 
 not touch. They become broader at a later stage, and the posi- 
 tion of the leaves, peculiar to the twisted aestivation, arises 
 from the mutual over- and inter-growth of their margins. 
 
 Fig. 1, PL IX. represents two horizontal sections of oppositely 
 rolled buds. By an examination of these it is readily ascertained 
 that the surfaces of the leaves are obliquely inclined to the centre 
 of the flower, and in the same direction in all the leaves of the 
 same flower. Either the leaves have been attached obliquely on 
 the receptacle from the first ; and then the twisted aestivation is 
 not the effect of a subsequent twisting of the separate leaflets, 
 and does not belong here ; or the leaflets are not originally 
 attached obliquely ; and then they can only be brought into the 
 oblique position subsequently evident, by a slight twisting. 
 Which of these two alternatives is the correct one, I could not 
 ascertain by direct observations, since the oblique position of 
 the leaflets only becomes perceptible by its effect, the growth of 
 the borders over and between each other. It is so slight, and 
 the curvature, if such occurs, is so lost in the earliest stages of 
 the bud, that it sinks to a microscopical magnitude, from the 
 transparency and delicacy of all the parts no longer recognizable 
 by the sight. On the other hand, conclusions may be drawn 
 from other perceptible facts, which give very reliable testimony 
 that the twisted aestivation owes its origin to a winding of the 
 individual leaflets. 
 
 15. 
 
 In the first place, an approximative testimony is furnished by 
 the occurrence of the twisted aestivation in gamopetalous corol- 
 las. The history of development of these, teaches us that they 
 
M. WICHURA ON THE WINDING OF LEAVES. 
 
 are composed, in the earliest periods of their formation, of sepa- 
 rate leaves which subsequently become blended together. It 
 will be admitted that if the " aestivatio contorta " depended on 
 an oblique attachment of the leaflets upon the receptacle, this 
 must exist from the moment of the origin of the leaf, and conse- 
 quently in those earliest periods of growth when the individual 
 parts of the gamopetalous corolla were not yet confluent. If 
 then, in the "aestivatio contorta," the oblique position of the 
 leaflets subsequently caused their borders, with the increasing 
 breadth, not to meet together, but to pass over and under one 
 another, this obliquity must, at the time when the confluence of 
 the separate foliaceous elements should commence, hinder their 
 coming into contact and consequently the confluence itself. 
 Hence oblique attachment of the foliaceous elements and gamo- 
 petalous growth seem to exclude each other, and if gamopetalous 
 corollas nevertheless do occur with rolled segments, it follows 
 that the rolled position in the bud cannot be explained by an 
 originally oblique attachment of the leaves. Then there only 
 remains the other alternative, that the foliaceous elements are 
 originally evenly attached, and only after confluence has oc- 
 curred, undergo a twisting of the free points, by which they are 
 brought into the position suited to the formation of the contorted 
 aestivation. 
 
 16. 
 
 I regard this proof as not wholly conclusive, only because it 
 is based upon suppositions which relate to the still somewhat 
 problematical processes of the confluence of the floral organs in 
 the earliest stages of development of the flower. But the twist- 
 ing of the leaflets on which the contorted aestivation depends, 
 was completely demonstrated by an observation which I had an 
 opportunity of making on a plant of Helicteres cultivated in the 
 Berlin Botanical Garden. The long and narrow petals of this 
 plant possess two opposite teeth on the margins, near the lower 
 part. In the bud, the teeth of the adjoining petals cover one 
 another in the manner of the " aestivatio contorta," as do like- 
 wise the upper parts of the little petals, but in an opposite di- 
 rection. While the right tooth of one leaf covers the left tooth 
 of the next leaf, the left margin covers, above, the right margin 
 
M. WICHURA ON THE WINDING OF LEAVES. 
 
 of the next leaf. It is clear that this contrast cannot be explained 
 by an oblique attachment of the young petals, since this can 
 only act in one direction : we are absolutely compelled to the 
 assumption that a curvature must have taken place here, which, 
 as we shall see, in many cases alters its direction within the 
 same leaf. 
 
 17. 
 
 The rolled buds also betray their close relationship with the 
 movement of winding in other respects. A comparatively very 
 large proportion of the plants in which the floral envelopes or 
 segments of the flower twist after the flower has opened, have 
 rolled buds ; for example : Puya ccerulea, Miers (Bromeliaceae), 
 Christya speciosa, Ward and Harv., Strophanthus divergens, 
 Graham (Apocynaceae), Pergularia edulis, E. M., P. accidens, 
 Blume, Diplolepis Menziesii, R. & S., Oxy pet alum riparium, 
 H. B. K. (Asclepiadaceae), Cyclamen europeeum, L., Lysimachia 
 punctata, Wall. We likewise frequently meet with rolled buds 
 which are at the same time twisted in one or other direction, as 
 in jEchmea latifolia, Kth. (Bromeliaceae), Strophanthus dicho- 
 tomus, D.C., Echites longiflora, Desf. (Apocynaceae), Pergularia 
 edulis, E. M., Microloma sagittata, R. Br. (Asclepiadaceae), Gil- 
 lenia trifoliata, Mcench. (Rosaceae), &c. From all these reasons, 
 therefore, I have no hesitation in regarding the " aestivatio con- 
 torta " as an effect of the movement of winding. 
 
 IV. Heliacal shape of Winding Leaves. 
 
 18- 
 
 The characteristic mark of all winding leaves is their heliacal 
 shape, with manifold modifications, however, depending on the 
 variability of the distance of the heliacal line from its axis, the 
 angle of inclination, and the length of the helix. 
 
 19- 
 
 The distance between the heliacal line of the leaf and the axis 
 of the helix may be either great or small. If it is reduced to 
 the smallest possible amount, it coincides with the median line 
 of the leaf itself. The fruit of Ailanthus glandulosus, L., repre- 
 
M. WICHURA ON THE WINDING OF LEAVES. 
 
 sented in figure 3, may serve as an example. If we draw a 
 straight line from the extreme point of this to its stalk, it will 
 cut through the substance of the leaf in its whole course. The 
 parts of the fruit lying in this direction consequently form a 
 straight line and consequently the fixed axis, around which the 
 halves on the right and left appear wound in the shape of a screw. 
 But if, on the contrary, the axis of the helix which the leaf 
 describes lies outside the latter, all parts of the leaf share in the 
 heliacal winding, and the leaf then resembles a band wound in 
 a heliacal direction round an invisible cylinder or cone, where 
 one side of the band is always turned towards the said cylinder 
 or cone. The axis of the heliacal winding in this case coincides 
 with that of the imaginary cylinder or cone. Leaves of this kind 
 occur much more frequently than the others. Some examples 
 are represented in figures 8 & 9. 
 
 20. 
 
 The angle of inclination of the heliacal winding, i. e. the angle 
 formed when a line is drawn through the helix parallel to its axis, is 
 in many leaves so small as to be imperceptible, for example in the 
 "aestivatio contorta;" in others it rises, judging from simple 
 inspection, which indeed leaves a wide field for error, to 30, 40, 
 or even 45. It therefore falls short of 90, the highest degree 
 mathematically possible, which would flatten the helix into a 
 plane. 
 
 21. 
 
 Lastly, the length of the helix is dependent on the length of 
 the leaf, or when only a part of this winds, on the length of 
 this portion. 
 
 22. 
 
 The sum of all these elements of the helix gives the number of 
 revolutions. The magnitude of the angle of inclination and the 
 length of the helix stand in direct, and its distance from the axis 
 in inverse, proportion thereto. The greater the angle of inclination 
 and the longer the helix, the higher the number ; the greater the 
 distance of the helix from the axis, the smaller the number of re- 
 volutions. Under otherwise like circumstances a broad leaf can 
 never complete so many revolutions as a narrow 7 one, because the 
 
M. WICHURA ON THE WINDING OF LEAVES. 2?3 
 
 helices which the margins of the leaf describe, at the same time 
 as the other parts, must be further removed from the axis in the 
 broad than in the narrow leaf. 
 
 23. 
 
 Consequently the greatest number of revolutions, from twenty 
 to twenty-five or even more, are found in the narrowest leaf- 
 structures, e.g. in the awns of the Grasses, the leaves of many 
 species of Gethyllis, &c., while elsewhere the most common 
 number of revolutions is from \ to 2. Although accurate pre- 
 determination is mostly impossible here, since the length and 
 breadth of the leaf, which influence the number of revolutions, 
 usually vary in the same plant, still at least approximative deter- 
 minations may be given for each species, and it is to be desired 
 that descriptive botany should include this in the subjects of its 
 observation. In flower-stalks which, as regards size and shape, 
 appear always more constant than the stem-leaves, the number 
 of revolutions of the heliacal windings admits of a tolerably exact 
 definition. 
 
 V. Rapidity of the Movement and Epoch of its Commencement. 
 
 24. 
 
 The winding movement takes place either rapidly or slowly. 
 In the appendages of the carpels which separate at the epoch of 
 maturity in the Geraniaceae, it is so rapid as to be visible to the 
 eye. In the other cases with which I am acquainted, we can 
 only conclude that a movement has taken place by recognizing 
 after long observation that a change of place has occurred. Days 
 or even weeks may elapse before the leaf has completed even 
 one revolution. 
 
 25. 
 
 In regard to the epoch of commencement, the movement is 
 connected with the stages of growth of the plant. It here fol- 
 lows definite laws, which however differ very much in different 
 plants. 
 
 26. 
 
 The "aestivatio contorta" affords the earliest traces of the 
 commencement of a movement of curvature. The extremely 
 SCIEN. MEM. Nat. Hist. VOL. I. PART IV. 18 
 
274 M. WICHURA ON THE WINDING OP LEAVES. 
 
 slight winding occurs here, it must be assumed, at an epoch 
 when the leaves are still quite imperfect, in fact scarcely visible 
 to the naked eye. 
 
 But in all other cases the winding does not commence until 
 the leaf has attained a certain magnitude and maturity. The 
 upper parts, as the older, wind first, the lower then gradually 
 follow. The winding of the older part likewise precedes that of 
 the younger in winding stems. But as in stems the lower parts 
 are older than the upper, while in the leaf the upper parts are 
 the older, the movement advances from below upwards in winding 
 stems, and in the leaf on the contrary from above downwards. 
 
 27. 
 
 In addition to these cases of a gradual origin and progress of 
 the movement, there are some in which the movement begins 
 suddenly and exhibits a more rapid course throughout its whole 
 duration. We then constantly observe that the stage of growth 
 which makes the commencement of the movement, is otherwise 
 of importance in the development of the plant. Thus the rather 
 rapid winding of the legumes of Medicago commences after 
 fertilization has taken place, that of the anthers of many plants 
 after dehiscence, of the petals of Cyclamen europceum, L., and a 
 number of other plants, after the flower has opened, of the 
 flowers of most species of the genus Aristea as soon as they begin 
 to wither, of the awns of Avena fatua and probably all other 
 Grasses with twisted awns, at the beginning of the maturation 
 of the seed, and of the appendages of the carpels of the Gera- 
 niaceaB after their separation from the carpophore. 
 
 t 
 28. 
 
 The movement of winding is in all these cases a rather trans- 
 itory phenomenon compared with the duration of the existence 
 of the plant, but it leaves permanent effects upon the shape of 
 the leaf. When a twisted leaf is unrolled, it returns to its posi- 
 tion as soon as released. It becomes " set " in the movement 
 which has taken place in it, and an unrolling and rolling up of 
 the heliacal winding may be produced in long dead awns of the 
 Grasses or in the fruit-stalks of Mosses, by unequal hygroscopic 
 expansion or contraction of their parts. 
 
M. WICHURA ON THE WINDING OF LEAVES. 275 
 
 VI. Mechanical Constituents of the Movement : Revolution round 
 the Axis and Curvature. 
 
 29. 
 
 The movement of winding is in all cases founded on a revolu- 
 tion of the leaf around the straight line which may be imagined 
 to pass from the point to the middle of its base. I call this the 
 axis of the leaf, to distinguish it from the axis of the helix, which, 
 as we have seen, may lie outside the substance of the leaf. This 
 revolution round the axis, with the resistance, increasing from 
 the freely moveable point down to the fixed base of the leaf, 
 which is opposed to it within the parts of the leaf itself, causes 
 a change in the relation of the direction of the parts of the leaf 
 to one another. Under its influence, the substance of the leaf, 
 originally expanded in a rectilinear plane, becomes converted 
 into a body wound in the form of a helix, within which only the 
 median line of the leaf, as the fixed axis around which the two 
 laterally situated halves revolve, retains its original position. 
 The forms of twisted leaves mentioned in 19, in which the axis 
 of the heliacal winding coincides with the axis of the leaf, are 
 consequently fully explained by the mere assumption of a re- 
 volution of the leaf round the axis. 
 
 Very frequently a curvature of the leaf is added to the revolu- 
 tion round the axis. Then a mixed movement is produced, 
 whence result the heliacally wound leaves with the axis of the 
 helix lying outside the leaf. That it is so may be strictly proved 
 mathematically by the aid of analysis. But a conviction of the 
 importance of the explanation given may be also readily obtained 
 in the empirical way, by holding a riband-shaped piece of wax 
 by one end, and twisting it around its long axis while curving it 
 at the same time toward one of its flat surfaces. In this way 
 are produced heliacal bands which agree in all essential points 
 with the forms of leaf represented in figures 8 and 9. 
 
 18* 
 
276 M. WICHURA ON THE WINDING OF LEAVES. 
 
 VII. Direction of the Movement of Curvature. 
 
 31. 
 
 The leaf may be curved, toward either the upper or lower 
 face. It follows from the nature of the mixed movement pro- 
 duced by a combination of curvature and revolution around the 
 axis, that the concave side of the curve is directed towards the 
 inside of the heliacal winding, the convex looking outward. 
 Wound leaves which are at the same time curved, are conse- 
 quently divisible into those with the upper and those with the 
 lower face turned to the inside of the winding. 
 
 32. 
 
 Examples of both kinds of winding leaves occur in nature. 
 To the first category belong, for instance, the stem- leaves of 
 most of our Gramineae and Liliaceae, to the latter the acicular 
 leaves of Pinus sylvestris, L., and the anthers of Erythraa Cen- 
 taurium, L. An individuality of a peculiar kind occurred on an 
 Allium transplanted from the Halle Botanical Garden to that of 
 Berlin, which was cultivated in the latter in the years 1848-49 
 under the name of A. simplex, and perhaps still exists there. 
 The two alternating series of opposite leaves of this plant were 
 curved to one side in the earliest condition, in such a manner 
 that in one series the upper and in the other the lower sides of 
 the leaves formed the curved surface. If revolution around the 
 axis is subsequently added to this, we get in one series leaves 
 with the lower faces, and in the other leaves with the upper 
 faces turned toward the interior of the helix. The two kinds of 
 wound leaves elsewhere only found, in the same leaf-metamor- 
 phosis, on different species, were here combined in the same 
 individual. 
 
 VIII. Direction of the Revolution around the Axis. 
 Terminology. 
 
 33. 
 
 In the revolution round the axis likewise only two different 
 directions are conceivable. They receive names from an oppo- 
 
M. WICHURA ON THE WINDING OF LEAVES. 277 
 
 sition in the dimensions of breadth, right and left. But botanists 
 are not agreed which of the two opposite helices shall be called 
 a right- and which a left-wound helix. According to Linnaeus, 
 the Bean winds to the right and the Hop to the left. This 
 definition is arrived at in standing outside the winding, and in 
 tracing the latter from below upwards with the face turned 
 towards it. In this way both the observer and the twining stem 
 examined retain their natural positions. DeCandolle proposed 
 an opposite method. In defining the direction of the winding, 
 he placed himself in the central point, and, on the contrary, 
 called the Hop right- and the Bean left- wound. Most modern 
 authors have followed him, because, as they say, " in every in- 
 dependent object, right and left can only be determined accord- 
 ing to itself, from its own above and below, front and back." 
 
 34. 
 
 The correctness of this reason, however, and the preference 
 herein claimed for the newer terminology, cannot be admitted. 
 According to Kant* the right or left nature of the winding of a 
 spiral is a distinction " which is indeed given in perception, but 
 cannot by any means be clearly conceived, and thus cannot be 
 made comprehensible/' We do indeed see, when we hold two 
 oppositely wound helices against each other, that they represent 
 a perfect contrast in their relations to space, and in this way we 
 acquire a conception. But the examination of either singly will 
 not carry us to the same result. All that we attain is a percep- 
 tion in regard to space, and thus terminology would have fully 
 gained its object, if it succeeded in reproducing in us the im- 
 pression of the direction in space of any helix. Both DeCandolle's 
 and Linnaeus' s methods fulfil this, but neither of these does any 
 more. I have therefore returned to the terminology of Linnaeus, 
 since it is not only the older, but also has the preference over 
 that of DeCandolle on account of greater convenience in use. 
 
 35. 
 
 Another remark which I have to make on terminology refers 
 to the " aestivatio contorta." Linnaeus called flower-buds rolled 
 according to the diagram fig. 1. no. 2, right- wound, in which the 
 * Afelaphysitche Anfangsyriindc, 1787, p. 8. 
 
278 M. WICHURA ON THE WINDING OF LEAVES. 
 
 right border of each leaf covers the left of its neighbour, and 
 those where the opposite case occurs, as in fig. 1. no. 1, left- 
 wound. But the diagram fig. 2 shows that the flower-buds 
 which Linnaeus called right-wound owe their origin to a revolu- 
 tion of the individual leaflets to the left, and vice versa. I shall 
 therefore deviate from the terminology of Linnreus in this point, 
 and call buds corresponding to the diagram figs. 1 & 2. no. 1. 
 right-wound, and those agreeing with figs. 1 & 2. no. 2. left-wound. 
 
 IX. Direction of the Revolution around the Axis in reference to 
 the Systematic Divisions of the Vegetable Kingdom. 
 
 36. 
 
 The direction in which leaves wind stands, like all the other 
 characters of plants, in a certain relation to the systematic sub- 
 divisions of the Vegetable Kingdom. Individuals of the same 
 species behave uniformly in the direction of the heliacally wound 
 leaves, and there are but few exceptions to this. Thus, for 
 instance, specimens of Medicago HttoraliS) Rohde, occur with 
 the legumes wound to the right and others with them wound to 
 the left. 
 
 37. 
 
 Whole genera including only uniformly winding species are 
 somewhat rare. When the direction changes within the same 
 genus, the species which have like laws of direction may some- 
 times be arranged in common subsections of the genus from 
 agreement also in other essential characters. The genus Allium 
 furnishes a remarkable proof of this. The Allia with left-wound 
 stem-leaves, as A. acutangulum, Schrad., A. Moly, L., &c., with 
 perhaps the single exception of A. azureum, Ledeb., all have a 
 leafless flowering stem, while right- wound stem- leaves occur 
 only in the species with a leafy flowering stem, as A. oleraceum, 
 L., A. spharocephalum, L., &c. 
 
 38. 
 
 Natural families in which winding leaves are frequent, usually 
 include species the leaves of which wind in different directions, 
 but there are certain families in which a perfect agreement 
 exists ; the petals of the Ebenaccnc, for instance, are in all cases 
 wound to the left in the bud. 
 
M. WICHURA ON THE WINDING OF LEAVES. 
 
 X. Change of the Direction in the Winding Leaves of the 
 same plant. 
 
 39. 
 
 Plants exist in the leaves of which only one direction, to the 
 right or left, is represented, others in which the leaves of one 
 individual exhibit both directions. Such a change of direction 
 in all cases presupposes a difference in the age or situation of 
 the parts of the plant, since two heliacal lines, one turning to 
 the right, the other to the left, form an absolute contrast, mutu- 
 ally exclusive, and so can only occur either on different bodies, 
 that is, in distinct places, or at different epochs of the existence 
 of the same body. 
 
 40. 
 
 The distinctions which, from the observations I have hitherto 
 made, usually accompany the change of direction, are: 1. The 
 different periods of age of the same leaf; 2. The differentiation 
 of the leaf in reference to point and base ; 3. The relative alti- 
 tude of the insertions of different leaves ; 4. The dissimilar lateral 
 insertion, both of the solitary and the verticillate leaves ; and 
 5. The metamorphosis of the leaf. 
 
 41. 
 
 Since, however, the change of direction depends, in some 
 plants on one, in others on another of these distinctions, there 
 exists a great variety in plants with winding leaves, which is 
 increased moreover by the fact that the lateral direction of the 
 helix, formed by the arrangement of the leaves, may affect in an 
 opposite way the direction of the heliacal winding of the leaves 
 themselves, so that the leaves are wound either in the same, or 
 in the opposite direction, to that of the leaf-spiral. We have 
 now to furnish some instances of the effect of those differences 
 of the position or relative age of the plant on the direction of 
 the heliacal winding. 
 
 42. 
 
 1 . Different periods of the age of the same Leaf. 
 
 The leaves of the inner circle of the perianth tfPuya carulea, 
 Miers, P. yuianensis, Kl., Bilbcryia zebrina Fam. of Brome- 
 
280 M. WICHURA ON THE WINDING OF LEAVES. 
 
 liaceze ; and the petals of Chrystea speciosa, Ward et Hartw., 
 Strophanthus divergens, Graham Fam. of Apocynaceas ; Cycla- 
 men europteum, L., Lysimachia punctata, Wallr. Fam. of Pri- 
 mulaceae ; are all wound to the left in the bud, and to the right 
 when the flower blows. The awns of Arrhenatherum elatum, 
 M. & K., at first wind slightly to the left below the angle ; sub- 
 sequently, as the seed is maturing, to the right in the same situa- 
 tion. It is probable that similar phenomena will be shown to 
 occur in very many Grasses with winding awns. The appendages 
 of the seed (beak of the carpel?) ofErodium cicutarium, L'Herit., 
 are wound to the left round the carpophore; after separating 
 from it they wind to the right. See PL IX. fig. 4. nos. 1 & 2. 
 
 43. 
 2. Differentiation of the Leaf in reference to Point and Base. 
 
 Alstroemeria pelegrina Fam. of Amaryllidaceae : stem- 
 leaves winding to the right at the apex and to the left near the 
 petiole. Avena sativa, L., and the allied species Phalaris minor, 
 L., &c., Lagurus ovatus, L. Fam. of Gramineae, and Xerotes 
 purpurea,JZnd\. Fam. of Juncaceae : stem -leaves wound to the 
 left at the points and to the right near the bases. (See fig. 5.) 
 In like manner the awns of many grasses, especially of the 
 genera Avena, Stipa, Danthonia, &c., in which the angle or 
 'knee 5 forms the boundary of the two oppositely-directed 
 windings, so that the curvature is to the left above the knee and 
 to the right below it. Chcetobromus Dregeanus, N. ab E., Ch. 
 strictus, N. ab E. : the palea runs out into two teeth above, the 
 awn being fitted in between them ; the two teeth wind to the left, 
 the awn to the right below and to the left above. Strophanthus 
 dichotomus, D.C. Fam. of Apocynaceae: the left- wound flower- 
 buds are slightly rolled to the left at their points and twisted to 
 the right below. A second change of the direction occurs in 
 the awns of Macrochloa arenaria, Koch. Immediately below 
 the knee they wind to the right, then further down to the left, 
 and quite at the bottom again to the right. The very long style 
 of Protea grandiflora, Thunb., changes three times to opposite 
 sides, but here the place which the two directions occupy is not 
 determinate, as in the examples above mentioned, for apparently 
 
M. WICHUBA ON THE WINDING OF LEAVES. 281 
 
 the right or left direction assumes the uppermost place without 
 any definite order. 
 
 A similar change of direction is met with in the tendrils of the 
 Passiflorce and the fruit-stalks of many Mosses. In the former 
 the relative situations of the two directions are indeterminate, as 
 in the styles of Protea grandiflora -, in the latter they are fixed. 
 The winding to the right is here usually uppermost, the winding 
 to the left in the lowest place. But the Funariea form an ex- 
 ception to this, since their fruit-stalks are wound to the left 
 above and to the right below. 
 
 44. 
 3. Different relative altitude of insertion of the Leaves. 
 
 Phalaris minor, L., Ph. c&rulescens, Desf., Ph. aspera, Retz., 
 Ph. canariensis, L., Ph. paradoxa, L. Fam. of Gramineae : 
 the first two leaves succeeding the cotyledon are wound to the 
 left, the succeeding leaves wind to the left at their points and 
 to the right below. In Avena sativa, L., and probably the allied 
 species, the first stem-leaf, developed after the cotyledon, winds 
 to the right, the following leaves wind to the left at the point 
 and to the right below, and finally the uppermost stem-leaves, 
 standing in the immediate vicinity of the inflorescence, wind to 
 the left. In Watsonia fulgens, Pers., and W. aletroides, Ker., 
 Fam. of Irideae as well as in many plants of the family of 
 the Grasses, e.g. Anthoxanthum odoratum, L., Calamagrosiis 
 Epigeios, L., Fesluca rubra, Huds., &c., right- and left-wound 
 leaves follow one another apparently without any fixed order. 
 
 45. 
 4. Unlike lateral insertion of solitary Leaves. 
 
 Dichcea squarrosa, Lindl. Fam. of Orchideae, Eucalyptus 
 viarginata, Lk., E. stenophylla, Lk., E. micrantha, D.C. Fam. 
 of Myrtaceae : the distichously alternate leaves are wound in 
 opposite directions on the opposite ranks. Chrysocoma Lino- 
 syris, L. (see fig. 6), GaJatella linifolia, D.C., G. punclata, D.C. 
 Fam. of Compositae, Andersomaprostrata, Sond., Sprengelia 
 incarnala Fam. of Epacridcac, Mdahuca stypheloides, L. 
 
282 M. WICHUBA ON THE WINDING OF LEAVES. 
 
 Fam. of the Myrtaceae and Acacia micracantha^ Desv. (see fig. 7) 
 Fam. of the Mimoseae have the stem-leaves wound in a helix 
 turning sometimes to the right, sometimes to the left, making 
 the helix by connecting the points of insertion of the leaves on 
 the stem, from below upwards, by the shortest line. In like 
 manner are the distichous or many-ranked verticillately-arranged 
 leaves of Pinus, e. g. P. sylvestris, L., P. Pinea, L., P. excelsa, 
 Wall., P. Mughus, Scop., &c., determined in the direction of 
 their winding by the direction of the helix which is described by 
 the succession of scales at the base of each fascicle of leaves. 
 The direction of this helix constantly agrees with the direction 
 in which the leaves wind. The reverse occurs in the petals of 
 Gillenia trifoliata, Moench. Fam. of Rosaceae; the Silenete 
 with three or several styles, e. g. Silene, Lychnis, Viscaria, Cu- 
 cubalus ; as also in the species of Hypericum, Geranium, Linum 
 and Oxalis, which in their contorted aestivation are wound in a 
 direction contrary to the readily distinguishable spiral of the 
 sepals. Probably the sometimes right-, sometimes left-w r ound 
 flower-buds of Statice, Fam. of Plantagineae, Lysinema, Fam. 
 of Epacridea3, Cistus, Fam. of Cistineae, Lavradia ericoides, 
 A. St. Hil., Fam. of Sauvagesieae, Bombaw, Helicteres, Fam. 
 of Sterculiaceae, Hermannia and Mahernia, Fam. of Byttne- 
 riaceae, Maronobea globulifera, L., Fam. of Clusiaceae, Rici- 
 nocarpus pinifolia, Desf., Fam. of Euphorbiaceae, and the 
 Malvaceae, are in like manner dependent on the direction of 
 the forerunning leaf-spiral. There is great difficulty, however, 
 in making out these, and I have not yet succeeded in deter- 
 mining their direction*. 
 
 46. 
 5. Unlike lateral insertion of verticil/ate Leaves. 
 
 Chironia frutescens, L., Ch. grandiftora, Fam. of Gentian eae : 
 stem-leaves in binate whorls. The leaves of the individual 
 whorls are wound in the same directions, the leaves of alternate 
 
 * The connection between the direction of the contorted aestivation and the 
 arrangement of the leaves was explained by Alexander Braun so long ago as 
 the year 1838, before the Naturforscher-Versammhing at Freiburg, Breisgau. 
 See A. Braun, On regular rotation (or twisting) in the Vegetable Kingdom. 
 Flora, 1839, i, 311 et seq. 
 
M. WICHURA ON THE WINDING OF LEAVES. 283 
 
 whorls toward opposite sides. Eucalyptus punctata, D.C., 
 E.floribunda, Hiigel, E. corymbosa, Sm. Fam. of Myrtaceae : 
 stem-leaves in binate whorls. In each individual whorl the 
 petioles of the opposite leaves are wound towards opposite sides. 
 In the parallel whorls, i. e. those which are separated by an in- 
 termediate, alternating whorl, leaves wound in like directions 
 are found upon the same sides. The same laws of direction are 
 followed by the stem-leaves of a Podocarpus, Fam. of Coniferae, 
 a specimen of which, consisting of a branch without flowers, 
 labelled " ex horto Liverpool/ 5 exists in the General- Herbarium 
 at Berlin. 
 
 47. 
 
 6. Different Metamorphoses of the Leaf. 
 
 Narcissus moschatus, L. : stem-leaves wound to the left, 
 segments of the perianth towards the right, after flowering. 
 ^Echmea, Puya, Pitcairnia, Billberyia, Tillandsia Fam. of Bro- 
 meliaceae: outer perigone wound to the right, the inner to 
 the left, in the bud. Pavetta indica, L., P. caffra, Thunb. &c. 
 Fam. of Rubiaceae : segments of the perianth wound to the 
 right in the bud, the bursting anthers to the left. Lychnis coro- 
 naritty Lam., L. chalcedonica, L., L.flos-cuculi, L., &c. : petals 
 wound in the bud in the direction contrary to the spiral of the 
 sepals, the style wound to the right. The same relation exists 
 between the petals and the appendages of the carpels in the 
 Geraniaceae. Chironiafrutescens,~L., Ch. grandiflora, Lam.: 
 stem-leaves on the alternate whorls wound in opposite direc- 
 tions ; petals in the bud and dehiscing anthers towards the left. 
 Arthrostemma Humboldtii, Fam. of Melastomaceae : sepals 
 wound to the left in the bud, the points of the anthers again to 
 the right. Cistus and Helianthemum : the three larger sepals 
 and the petals wound in opposite directions in the bud, Con- 
 sequently, were it correct (see 45.) that the petals of the Cis- 
 tineae wind in the bud, in the direction opposed to that of the 
 leaf- spiral, the sepals must be wound in the same direction as 
 the latter. 
 
284 M. WICIIURA ON THE WINDING OF LEAVES. 
 
 XI. Regular Succession of the two Opposite Directions. 
 
 48. 
 
 The examples of leaves which wind toward opposite sides, 
 mentioned in 12, all agree in the circumstance that the direc- 
 tion to the left invariably precedes the subsequently occurring 
 winding towards the right. The leaves with their points and 
 bases wound in opposite directions exhibit a similar condition. 
 With the single exception of Alstrcemeria pelegrina, the upper 
 part of the leaf always winds to the left, the lower part to the 
 right. Here therefore the winding to the left likewise precedes 
 the winding to the right, since the upper portion of the convo- 
 luted organs is always older than the lower. 
 
 49 
 
 The application of the same law may further be shown in 
 organs wound only in one direction, insofar as they are to be re- 
 garded, either wholly or in the winding part, as metamorphosed 
 summits or bases of leaves. The summits of leaves, consequently 
 the style, stigmas, anthers, and, above all, the petals in contorted 
 aestivations, which wind at a period w 7 hen the point only of the 
 leaf has been protruded from the receptacle, follow the direc- 
 tion toward the left in a vast majority of cases. The blade of 
 the stem-leaves, as a superior region, is most generally, although 
 not quite so frequently, wound to the left, while the sepals and 
 carpels, as metamorphosed forms of the sheathing portion of the 
 leaf, are predominantly wound to the right. 
 
 50. 
 
 From this it follows that the two directions to the right and 
 left stand in a fixed relation to the different periods of the age 
 of the leaf, which at the same time have their material expres- 
 sion in the upper and lower parts of these organs. The winding 
 to the left belongs to the earlier period of growth, and occurs 
 chiefly in the upper parts of the leaf. The winding to the right 
 follows at a later period, and is connected principally with the 
 upper parts of the leaf. Since the stem, considered in relation 
 to the leaf, represents a structure standing underneath, it is 
 completely in consonance with this law 7 , that, as we find, the 
 
M. WICHURA ON THE WINDING OF LEAVES. 285 
 
 winding stems are turned to the right in about the same pro- 
 portionate majority of cases, as the petals, at the other pole, are 
 wound to the left in the contorted aestivation. 
 
 51- 
 
 The relations are somewhat different in the Mosses. As 
 already mentioned, the winding to the right occupies the upper 
 part, that to the left the lower part of the fruit-stalks of Mosses. 
 The winding fruit-stalks of the Mosses are further distinguished 
 from the leaves of Vascular plants by the circumstance that in 
 the latter the upper winding is developed before the lower, 
 while in the former the lower is shown before the upper. Since 
 then the lower winding of the fruit-stalk of the Mosses is directed 
 to the left and the upper to the right, the winding to the left 
 precedes that towards the right here also. The only exception 
 to this occurs in the fruit-stalks of the Funariece, which wind 
 to the right below and to the left above ; and in these, therefore, 
 the winding to the right precedes that towards the left. 
 
 52. 
 
 A similar relation to that just demonstrated between the 
 winding to the left and right and the earlier and later, or upper 
 and lower parts of the leaf, may perhaps be assumed of the 
 windings which derive their determination from the direction of 
 the leaf-spiral, either in the positive or negative sense. We are 
 led to this conjecture by the fact that leaves wound in the direc- 
 tion opposite to the leaf-spiral occur only in the contorted aesti- 
 vation, and leaves following the direction of the latter, only on 
 circles of stem-leaves, and perhaps the sepals of the family of 
 Cistineae. The contorted aestivation, on account of the wind- 
 ings, perfectly determinate in their direction in all cases, is espe- 
 cially important, as the principal seat of the upper winding, 
 from the fact that the wound flower-buds take the direction 
 toward the left in a preponderating multitude of cases. It is 
 very probable that a similar import is to be ascribed to it, to 
 that of windings determined in their direction by the leaf-spiral. 
 Under this hypothesis, therefore, we should have to regard the 
 winding contrary to the direction of the leaf-spiral as the upper 
 or earlier, the direction of the leaf-spiral as the lower and later. 
 
286 M. WICnURA ON THE WINDING OF LEAVES. 
 
 XII. Direction of Winding Leaves in relation to the Direction 
 
 of the Winding Stem. 
 
 53. 
 
 The movement of winding displays itself in two different forms 
 in the stems of plants. There are stems which by their move- 
 ment twine round a support, and stems which, like winding 
 leaves, complete their movement in freedom without twining 
 round a prop. The remark made above, that stems, as structures 
 situated below, wind predominantly toward the right, and thus 
 form a contrast to the blades of the stem-leaves more frequently 
 winding to the left, holds good, as it remarkably appears, only 
 of winding stems of the former kind. The hitherto little-known 
 winding stems of the latter kind, which occur not unfrequently 
 in the Monocotyledons, wind always in the direction in which 
 the stem-leaves of these plants are \vound. Thus we find left- 
 wound flower-stems and stem-leaves in Eleocharis palustris, 
 R. Br., Fam. of Cyperaceae ; in all the species of Xyris, Fam. of 
 Xyridaceae, with which I am acquainted ; in Butomus umbella- 
 tus, Fam. of Butomese ; Allium acutangulum, Schrd. ; All.fallax, 
 Don ; All. ursinum, L. ; All. Stellerianum, Willd. ; AH.flaves- 
 cenSy Bess. ; Tulbaghia alliacea, L. ; T. cepacea, L., Fam. of 
 Liliaceae; Leucojum cestivum, L., Fam. of Amaryllideae. Right- 
 wound flowering- stems and stem-leaves in Aristidea megapota- 
 mica, Spr., Fam. of Gramineae ; P&palanthus perpusillus, Kl. ; 
 P. Ottonis, KL, Fam. of Eriocauloneae; MorceafiliformiSjThurib., 
 Fam. of Irideae. Lastly, in Sisirynchium anceps, belonging to 
 the family of the Irideas, the leaves and stems of some speci- 
 mens wind to the right, those of others to the left, so that in 
 spite of the change of direction occurring in the same species, 
 leaves and stem are always wound toward the same side in the 
 same individual. 
 
 XIII. Individual observations on the Direction of the convolution 
 round the axis, collocated in the order of the Natural Families. 
 
 54. 
 
 It is a very remarkable phenomenon that the circularly or 
 heliacally acting forces of nature follow an unchanging, definite 
 
M. WICHURA ON THE WINDING OF LEAVES. 287 
 
 lateral direction in their course. In cosmical nature the planets 
 describe heliacal lines winding to the right in space, by virtue 
 of their circulation from west to east, since this is combined with 
 the advance, in company with the sun, toward a point in the 
 northern hemisphere. In the department of physics we meet 
 with allied phenomena in the circular polarization of light and 
 in the course of electro-magnetic spirals. Organic life exhibits 
 the same laws in the circulation of the blood, in all cases starting 
 from the left side of the animal body, and in the heliacal 
 windings of the shells of Mollusks, which follow a direction 
 determinate for every species. But plants above all give evi- 
 dence of a wonderful obedience to such laws, in the direction 
 of the spiral vessels, the heliacally winding trunks of trees, 
 winding stems and leaves, and probably also in the circulation 
 of their saps. In regard to the conceptions formed by the in- 
 tellect, it makes no difference at all in our views of the essential 
 nature of any force working in lateral direction, whether it sets 
 out towards the right or the left. In the rare cases in which 
 the human heart has been placed in the right side instead of the 
 left, it has been demonstrated that this anomaly did not interfere 
 with the vital powers of the body, Nevertheless, Nature, as 
 though dealing here with the most important business, displays 
 the most surprising regularity in this very lateral direction. 
 This apparent contradiction between our ideas and the phaeno- 
 mena of Nature has something in it so remarkable, that a rather 
 detailed account of observations on this particular point may 
 seem desirable. I shall therefore here subjoin my observations 
 on the direction peculiar to winding leaves, singly, in the order 
 of the Natural Families. This collocation will at the same time 
 serve to furnish a summary of the material of which I made use. 
 
 55. 
 
 Jungermanniaceae. Jungermannia Trichomanis, Dicks. : de- 
 hiscent valves of the fruit wound to the left. 
 
 56. 
 
 Musci frondosi. Cinclidotus fontinaloides ; Dichelyma falca- 
 tum ; Bartramia pomiformis, Hedw. ; Tortula ruralis, Swartz : 
 stem-leaves wound to the right. Cinclidotus 9 Barbula, and 
 
288 M. WICHURA ON THE WINDING OF LEAVES. 
 
 Syntrichia : teeth of the capsules, to the right. Encalypta strep- 
 tocarpa, Hedw. ; Barbula rigida : walls of the capsules, right. 
 Barbula anomala, Br. & Sch., furnishes a solitary example of a 
 Moss with the teeth of the capsule winding to the left. From 
 the notice on this plant in the ( Europaischen Laubmoose/ 
 however, " Peristomii denies complures ad dextrum (i. e. to the 
 left in the Linnaean sense) convoluti" it would appear that in- 
 stances of the opposite winding also occur, and it would be 
 interesting to discover whether the fruit-stalks also are wound 
 in the contrary direction when the teeth of the capsule are* 
 I have not seen this plant. 
 
 57. 
 
 Fiiices. Lygodium circinatum, Swtz.; L. salicifolium, Presl; 
 L. polymorphism, H. B. & K. : midrib of the frond without defi- 
 nite order, sometimes to the right, sometimes to the left. 
 Palm* saw two stems of Ophioglossum japonicum (with which 
 I am unacquainted) wound round one another toward the right, 
 that is, to the left in our terminology. 
 
 58. 
 
 Lycopodiaceas. Lycopodium contiyuum, Kl. ; L. mendiocca- 
 num, Raddi ; L.inundatumi stem-leaves slightly wound, with 
 prevailing but not exclusive direction toward the right. 
 
 59. 
 Graminacese f. 
 
 1. Oryzeae. Caryochloa chilensis, Spr. : awns right. 
 
 2. Phalaridece. Phleum, Alopecurus, and Beckmannia : stem- 
 leaves constantly left. Baldingera arundinacea, Gaert. ; Holcus 
 lanafuSy L. ; H. mollis, L. ; Hierochloa borealis, R. et S. : stem- 
 leaves right. Anthoxanthum avenaceum, Retz. : awns right at 
 the lower part. For the species of Phalaris see 44. 
 
 3. Panicea. Setaria verticillata, Beauv. ; S.viridis, Beauv. ; 
 S. glauca, Beauv. ; Pennisetwnfasciculatum, Trin. : stem-leaves 
 
 * Ueber das Winden dcr PJJanzen. Stuttgart, 1827, pp. 41, 42. 
 
 f See Alex. Braun on the Italian Rye-grass, ' Flora,' 1834, Jahrg. xvii. 
 Bd. 1. 262, 263, whose attention was already directed to the property of Grass 
 leaves and the awns, of curling in definite directions. 
 
M. WICHURA ON THE WINDING OF LEAVES. 289 
 
 right. Apparently the winding of the leaves is more rare in 
 this section, inclined to a broader development of the leaves. 
 
 4. Stipacece. Stipa mongolica, Turcz. ; Lasiagrostis Calama- 
 grostis, Lk. ; Aristida megapotamica, Spr. : stem-leaves right. 
 Aristida vestita, Thunb. ; A. chapadensis, Trin. ; A. Kotschyi, 
 Hochst.; A. divaricata, H. B.W. ; A. Sieberiana, Trin.. &c. : 
 lower paleas of the flowers right. 
 
 5. AgrostidetR. Polypogon monspeliensis, Desf. ; P. mexicanus, 
 Spr. ; Agrostis canina, L. ; A. vulgaris, Withering : stem-leaves 
 right. Apera Spica-venti, Beauv. : stem-leaves left. 
 
 6. Arundinacea. Calamagrostis Halleriana, D.C.; C.Langs- 
 dorfii, Trin. ; C. littorea, D.C. ; Arundo poceformis, Labil. : stem- 
 leaves right. Desyeuxia retrofracta, Kth. ; Lachnagrostis splen- 
 dens, Trin. : stem-leaves left. Calamagrostis sylvatica, R. Br., 
 and Desyeuxia eriantha, H. B. K. : awns right at the lower part. 
 For the stem-leaves of Calamagrostis Epigeios, Roth, see 44. 
 
 7. Chloridece. Chloris petr&a, Sw. ; Diplachne poa/ormis, 
 Hochst. : stem-leaves right. 
 
 8. Avenaceas. Air a bottnica, Wahlenb. ; Avenaflavescens, L. : 
 stem-leaves right. Trisetum neglectum, R. & S. ; TV. Alopecurus, 
 R. & S. : stem-leaves left. For the doubly wound stem-leaves 
 and awns of the Avenaceae, as also the doubly wound awns of 
 the Grasses generally, see 42, 43. 
 
 9. Festucacece. Poa, Bromus, Festuca Myuros, L. : stem- 
 leaves left. Festuca alpina, Sut. ; F. arundinacea, Liljebl. ; 
 F. pratensis, Huds. ; Bromus c&spitosus, Host. ; Br. rupestris 9 
 Host.; Brachypodium ramosum, R, & S.; Cynosurus echinatus, L.; 
 Briza media, L. ; Melica pyramidalis, Lam. : stem-leaves right. 
 As the genera Bromus and Festuca are so extremely nearly allied, 
 it is important for their distinction that the former are predomi- 
 nantly wound to the left, the latter to the right. For the stem- 
 leaves of Festuca rubra, Huds., and Melica altissima, see 44. 
 Bromus ?nadritensis, L. ; Br. rubens, L. ; Br. scaberrimus, Te- 
 nore : awns slightly left. Bromus confertus, M. B. ; Br. wol- 
 gensis, Spr. ; Br. patulus, M. & K. ; Br. lanceolatus, Roth : awns 
 slightly left. 
 
 10. Hordeacece. Lolium: stem-leaves right. Triticum, Se- 
 cale, Elymus, Mgilops: stem-leaves left. Elymus Caput-Me- 
 dusa, L. ; E. platantherus, L. : awns left. 
 
 SCIEN. MEM. Nat. Hist. VOL. I. PART IV. 19 
 
290 M. WICHURA ON THE WINDING OF LEAVES. 
 
 11. Rottbcelliacece* Lepturus incurvatus, Trin. : stem-leaves 
 right. Hemarthria fasciculata, Kth. : stem-leaves left. 
 
 12. Andropogonea. Tricholcena tonsa, N. ab E. ; Elionurus 
 argenteus, N. ab E. : stem-leaves right. Saccharum cylindricum : 
 stem-leaves left. Apluda microstachya, N. ab E. : stem torn at 
 the apex into filiform strips which wind to the left. Anthistiria 
 Wightii, N. ab E. ; A. tremula, N. ab E.; A. abyssinica, Hochst. : 
 awns right at their lower part. Erianthus contortus, Elliot : 
 awns left. 
 
 60. 
 
 Cyperacea. Cyperus reflexus, Vahl ; Cyp. difformis, L. ; 
 Cyp. auricomus, Sieb. : stem-leaves right. Papyrus antiquorum, 
 Willd. : the narrow glumes enveloping the inflorescence right. 
 Chrysithrix capensis, L. ; Fimbristylis torta, Kth. ; Eleocharis 
 palustriS) R. Br. : stem-leaves left. Carex hirta, L. ; C. ampul- 
 lacea. Good. ; Rhyncospora alba, Vahl ; Schcenus nigricans, L. ; 
 Fimbristylis ferruginea, Vahl ; F. junciformis, Kth. ; Androtri- 
 chum polycephalum, Kth. ; Ficinia striata, Kth. ; Eleocharis 
 glaucescens, Schult. ; E. palustris, R. Br. ; E. uniglumis, Lk. ; 
 Scirpus maritimus, K. ; Scirpus glaucus, N. ab E. ; Eriophorum 
 gracile, Koch ; E. latifolium, Hoppe : anthers left when de- 
 hiscent. 
 
 61. 
 
 Eriocaulonea. Papalanthm perpusilhis, Kl. ; P. Ottonis, Kl. : 
 stem-leaves right. 
 
 62. 
 
 Xyrideae. Xyris communis, Kth. ; X. subulata, R. & P. ; 
 X. arescens, Kth. ; X. strobilifera, Kth. ; X. metallica, Kl. : stem- 
 leaves left. 
 
 63. 
 
 Commelinacea. Tradescantia Lyoni : stem-leaves left; I must 
 remark, however, that I have seen but one specimen of this 
 plant, on the " Pfauen-Insel," near Potsdam. 
 
 64. 
 
 Juncaginea. Scheuchzeria palustris, L. This plant presents 
 individuals with right- and others with left-wound leaves. 
 Leaves of the same specimen wind constantly in the same 
 
M. WICHURA ON THE WINDING OF LEAVES. 291 
 
 direction. Perhaps the direction of the leaf-spiral has an influ- 
 ence here in the direction of the winding, producing, by its 
 difference in different specimens, a corresponding difference in 
 the direction of the winding leaves. I have no exact observa- 
 tions on this point. 
 
 Butomacece. Butomus umbellatus, L. : stem-leaves left. 
 
 65. 
 
 Juncacece. Xerotes mucronata, R. Br. ; X. aemula, R. Br. ; 
 X. effusa, Endl. ; X. suaveolens, Endl. ; X. rupestris, Endl. ; 
 X. micrantha, Endl.; X.flexifolia, R. Br. ; X. rigida, R. Br. ; 
 X. longifolia, R. Br. : stem-leaves left. Xerotes umbrosa, Endl., 
 and two species from Major Mitchell's Expedition, distributed 
 unnamed under the Nos. 542 and 564 : stem-leaves right On 
 the doubly-wound leaves of Xerotes purpurea, Endl., see 43. 
 The stem-leaves of some species of Juncus, in particular Juncus 
 compressuSy Jacq., seem to behave like the stem-leaves ofScheuch- 
 zeria. In many specimens the leaves wind to the left, in others 
 to the right; the right- winding predominate. Luzula albida, 
 D.C. ; L. campestris, D.C. ; anthers after dehiscence left. The 
 stigmas of all the species of Juncus and Luzula with which I am 
 acquainted wind to the left before the flower opens. 
 
 65*. 
 
 Melanthacece. Tofieldia calyculata, Wahlenb. ; Colchicum 
 Szovitsiiy Fisch. et Meyer ; C. autumnale, L. ; C. variegatum, 
 Bivon : stem-leaves left. Merendera caucasica, M. B. : stem- 
 leaves slightly right. 
 
 66. 
 
 Liliacea. Ornithogalum umbellatum, L. ; 0. Gussonii, Ten. ; 
 O. lanceolatum, Labill. ; Bulbine annua, Willd. ; Johnsonia mu- 
 cronata, Endl., as well as all the numerous species of the genera 
 Lilium, Eremurus and Asphodelus I have seen : stem-leaves right. 
 Hyacinthus orientalis, L. ; Thysanotus proliferus, Lindl. ; Tul- 
 baghia alliacea, L.; T.cepacea,ii.; AcanthocarpusPreissii 9 Lehm.: 
 stem-leaves left. In the genus Fritillaria occur species with 
 left- and with right-winding leaves. To the former belong, for 
 example, F. imperialis, L. ; F. Meleagris, L., &c. ; to the latter, 
 
 19* 
 
292 M.WICHURA ON THE WINDING OF LEAVES. 
 
 F. pyrenaica, L., and F. montana, Hoppe. Between many of 
 the oppositely winding species there exists so close an affinity 
 that hybridizing would be most probably successful. It would 
 be interesting to discover the direction in which the leaves of 
 such a hybrid would wind. For the winding leaves of the 
 Allia see 37. Gagea minima, Salisb. : segments of the peri- 
 anth left during the withering of the flower. Massonia latifolia, 
 L. : the filiform bracts of the flowers right. 
 
 67- 
 
 Smilacea. Streptopus perfoliatus, L. : segments of the peri- 
 anth left after the flower has opened. Paris quadrifolia, L. : 
 the attenuated points of the four st'em-leaves, the leaflets of the 
 perigone, both those of the inner and the outer, wind to the left 
 in the bud in the contorted aestivation, and likewise after the 
 flower has opened; finally also the dehiscing anthers and the 
 style, all left, 
 
 68. 
 
 Hamadoracece. Conostylis bracteata, Hcemodorumplanifoliumi 
 stem-leaves right. Barbacenia tricolor., Mart. : stem-leaves 
 rolled together like ringlets, without definable order, sometimes 
 left, sometimes right. Vellozia variabilis, Mart. : the dehiscing 
 anthers left. 
 
 69. 
 
 Hypoxidea. Hypoxis gracilis, Lehm. ; Curculigo brevifolia : 
 stem-leaves right. 
 
 70. 
 
 Iridea. Moraa filiformis, Thunb. ; Tritonia lineata, Ker.; 
 all the species I know of Ixia and Gladiolus, together with the 
 species of Iris with straight, narrow, linear leaves, e. g. Iris si- 
 birica, L. ; /. Pallasii, Goldb. ; Trichonema chloroleucum, Ker., 
 and several species of Tritonia which were temporarily culti- 
 vated without names in the Berlin Botanic Garden in 1848 : 
 stem-leaves left. In the species of Iris with broad, sabre- 
 shaped leaves, e. g. /. lurida, Ait., 7. germanica, L., and /. Pseud- 
 AcoruSy the attenuated points wind sometimes right and some- 
 times left. For Watsoniafulgens, Pers., and W. aktroides, Ker., 
 
M.WICHURA ON THE WINDING OF LEAVES. 293 
 
 see 44 ; for Sisyrinchium anceps, 53. The petals of the spe- 
 cies of Iris are constantly wound to the left in the contorted 
 aestivation. Aristea cyanea, Ait. ; A. bracteata, Pers. ; A. ca- 
 pitata, Gawl. ; A. carulea, Vahl ; A. spiralis, Vahl : petals wind- 
 ing to the left as the flowers wither. The withering flowers of 
 Iris exhibit the same twistings, apparently however without de- 
 finite direction. 
 
 71. 
 
 Amaryllidece. Hitherto I have only met with left-wound 
 stem-leaves in this family. The species examined were : Leu- 
 cojum (pstivum, L. ; Sternbergia colchiciflora, W. K. ; Brunsvi- 
 gla Josephines, Ker. ; a Cyrtanthus, the leaf of which is repre- 
 sented in fig. 8 ; Zephyr anthes Candida, Herb., several species 
 of Narcissus, Gethyllis and Alstrcemeria. For the doubly- 
 wound stem-leaves of Alstrcemeria pelegrina, see 43. Narcis- 
 sus moschatus, L. : petals right soon after the flower opens. 
 Pancratium patens. Red. ; P. expansum, W. Herb. ; P. lobatum, 
 Kl. : dehiscing anthers right. 
 
 72. 
 
 Bromeliacece. See 4? and 42, for the winding of the 
 outer and inner perianth in the bud, and of the leaves of the inner 
 perigone after the flower is open. We also observe a constant 
 winding towards the left in the style. 
 
 73. 
 
 Orchidea. Epidendrum macrochilum, Hook.; Scaphy glottis 
 violacea, Cyrtochilum flavescens, Diuris filifolia, Lindl. : stem- 
 leaves left. Ornithidium album. Hook. ; Cymbidium giganteum ; 
 Disa Zeyheri, Sond. ; D. tenella, Sw. : stern-leaves right. For 
 Dichaa squarrosa, Lindl., see 45. Epidendrum cochleatum, 
 L. ; Trichopilia tortilis, Lindl. : perigonial leaflets left, with the 
 exception of the labellum which does not wind. Orchis hircina, 
 Scop. : lobes of the labellum, especially the long middle lobes, 
 left. Cypripedium Calceolus, L. : the pair of corresponding 
 segments of the outer perigone right. Every one is aware of 
 the half revolution of the germen of many Orchideae, by which 
 the position of the parts of the flower in relation to the axis of 
 
294 M. WICHURA ON THE WINDING OF LEAVES. 
 
 the inflorescence appears reversed, so that the labellum comes 
 to the front, while in its original position it is turned towards 
 the axis. No definite direction can be detected in this winding ; 
 right- and left-wound ovaries succeed one another quite irregu- 
 larly. It is possible that this revolution is a mere effect of 
 irritability, caused by the effort of the labellum to assume an 
 external position, corresponding to its greater proportionate de- 
 velopment. 
 
 74. 
 Aroidece. Acorus Calamus, L. : stem-leaves left. 
 
 75. 
 
 Typhacea. Typha lattfolia, L. ; T. angustifolia, L. ; T. ste- 
 nophylla $ Sparganium ramosum, Huds. : stem-leaves left. Spar- 
 ganium natans, L. : stem-leaves right. The only example I 
 know of a plant winding under water. The winding may be 
 frequently prevented, or its effects renderea imperceptible even by 
 slow flowing of the water. But I observed it very clearly in 
 July 1847, on the heath behind Moabit, near Berlin, in little 
 pools where the undisturbed development of the leaves was 
 favoured by the calm and clearness of the water. 
 
 76. 
 
 Pdlma. Maximiliana insignis, Mart. : anthers mostly right-, 
 but occasionally left-wound. 
 
 77. 
 
 Coniferce. For the acicular leaves of the species of Pinus, 
 see 45. Podocarpus elongatus, L'Herit. ; P. macrophyllus, 
 Wall. ; P.falcatus, L'Herit., and P. latifolius, Wall. : stalks of 
 the stem-leaves and lowest part of the blades right. 
 
 78- 
 
 Casuarinece. Casuarina suberosa, Otto and Dietr., and a 
 Casuarina from Cuming, discovered in the Philippines and 
 distributed as No. 730 : sheath-teeth right. Casuarina humilis, 
 Otto and Dietr. ; C. quadrivalvis, Labill., and C. suberosa, Otto 
 and Dietr. : style left. 
 
M. WICHURA ON THE WINDING OF LEAVES. 295 
 
 79. 
 
 Salicinea. Salix stipularis, Sm. : branches of the stigma 
 right when dried up. 
 
 80. 
 
 Nyctaginece. Bugainvillea spectabilis : withering flowers right. 
 Pisonia grandis, R. Br. ; a plant which I have never seen my- 
 self, but which is represented with right-wound styles in Endli- 
 cher's < Iconographia ' (Vindob. 1838). 
 
 81. 
 
 Gyrocarpea. According to Nees v. Esenbeck, Wallich, 
 Plantae Asiaticae rariores, ii. 68, the cotyledons are wound 
 heliacally round the two-leaved plumule : I have had no oppor- 
 tunity of observing for myself. The direction of the winding is 
 unknown. 
 
 82. 
 
 Santalacece. Thesium ramosum, Hayne : stem-leaves left. 
 The stem-leaves of Thesium pratense, Ehrh., and Th. ebractea- 
 tum, Hayne, are also often wound, but not in any definite direc- 
 tion. Santalum cognatum, Miquel : petioles left, not quite . 
 
 83. 
 
 Daphnoideae. Passerina pectinata: stem-leaves slightly to 
 the left. The same in Daphne oletefolia, Lam. 
 
 84. 
 
 Proteacece.Persoonia quinquenervia 3 Hook. ; Hakea steno- 
 carpa, R. Br. ; H. latifolia, Loddig. ; Protea longiflora, Lam. ; 
 Pr. inflexa, Willd. ; almost all species of Leucadendrum, e. g. L. 
 ascendens, R. Br. ; L. diversifolium, R. Br. ; L. tortum, R. Br. ; 
 L. cuspidatum, Kl. ? &c. : stem-leaves left ; in Hakea latifolia, 
 Loddig., it is the attenuated points of the leaves which wind, in 
 the rest the lower parts of the leaves which run down into an 
 imperfect petiole. Conospermum capitatum, R. Br. : the narrow 
 stem-leaves, nearly a foot long, right. Conospermum teretifolium, 
 R. Br. : petals in the bud twisted like a cord to the left. For 
 the winding style of Protea longijlora y see 43. 
 
296 M. WICHURA ON THE WINDING OF LEAVES. 
 
 85. 
 
 Plumbaginea. Armeria, in all the species with which I am 
 acquainted : petals wound to the left in the contorted aestivation. 
 The genus Armeria is essentially distinguished by this point 
 from the allied genus Statice, in the distichous inflorescence of 
 which right- and left- wound buds alternate regularly. But this 
 law seems only to be manifested clearly in the blue-flowered 
 species of the genus Statice. Two red-flowered species, one of 
 which is St. acicularis, exhibited a predominance of right-wound 
 flower-buds, with the intermixture of a small number of left- 
 wound. 
 
 86. 
 
 Composite. Liatris punctata, Hook. ; L. cylindracea, MX. ; 
 L. squarrosa, L. ciliata ; Eclopes parallelinervis, Lessing ; Gero- 
 pogon glaber : stem-leaves right. Cephalophora aromatica, 
 Schrad. ; Calycadenia villosa, D.C.; C. cephalotes, D.C.; Me- 
 talasia, R. Br. ; Stabe, Less. almost all the species of these 
 genera Perotriche tortilis, Cass. ; Erythropogon umbellatum, 
 D.C.; Elytropappus glandulosus, Less.; E. ambiguus, D.C. ; 
 Disparage ericoides, Gaertn.; D. lasiocarpa, Cass.; Centaurea 
 depressa, M. B. : stein-leaves left. For Galatella and Chryso- 
 coma, see 45. Podolepis subulata, Steetz: points of the 
 membranous leaves of the anthodium not quite % right. 
 Prenanthes purpurea, L. : radiant florets thrown back toward 
 the left. R. Brown has directed attention to the windings of 
 the style to the extent of about |- of its circumference. The 
 arms of the stigma which stand front and back in reference to 
 the axis of the inflorescence, are thus brought into a lateral 
 position. I have observed this phenomenon, not in all, but in 
 a great multitude of Compositag, and have never detected a de- 
 finite law of direction. 
 
 87. 
 
 Campanulaceae. Campanula Loreyi, Pollin. : apex of the calyx 
 left. Campanula patula, L. ; (7. Rapunculus, L. ; C. Lcefflingii, 
 Brot. ; C. persicifolia, L. ; C. cana, Wall. ; Phyteuma canescens, 
 W. et K. : dehiscing anthers to the right. Campanula rapun- 
 culoides, L. ; C. Trachelium, L. ; C. glomerata, L. ; C. bar bat a, 
 
M. WICHUBA ON THE WINDING OF LEAVES. 29? 
 
 L. ; C. Loreyi, Pollin. ; C. Medium, L. : dehiscing anthers left. 
 The species in which the anthers wind to the same side, exhibit 
 a certain agreement in their habit, which indicated that the two 
 groups which are distinguished from each other by the opposite 
 winding of their anthers may also be separated by other cha- 
 racters. But this requires a more exact knowledge of this 
 large genus than I possess. 
 
 88. 
 
 Stylidea. A slight revolution of the corolla brings the anterior, 
 odd petal into a lateral position. I have only examined one 
 species of this genus, which was cultivated in the Berlin Garden 
 under the name of Stylidium suffruticosum. In this the winding 
 of the corollas was without exception directed to the left. 
 
 89. 
 
 Rubiacea. Pavetta indica, L. ; P. Caffra, Thunb. ; P. lan- 
 ceolata, Ecklon ; P. manitensis, Walpers ; P. longissima, Kl. ; 
 Ixora Bondhuca, Rxbrg. ; /. acuminata, Rxbrg. ; /. parviflora, 
 Vahl ; /. nigricans, R. Br. ; Wendlandia coriacea, Vahl ; Augusta 
 lanceolata^ Pohl, Randiaferox, D.C.; Gardenia latifolia, Rxbrg.: 
 segments of the flowers right on the contorted aestivation. Exo- 
 stemma maynense, Pcepp. : segments of the flower left in the bud. 
 Coffea arabica, L. ; Gardenia latifolia, Rxbrg. : dehiscing anthers 
 right. Pavetta (the above-mentioned species) : dehiscing anthers 
 left. The anthers of Gardenia latifolia, Rxbrg., and Pavetta, con- 
 sequently follow opposite directions in their winding, while the 
 segments of the flowers of both are turned in the same direction. 
 
 90. 
 
 Jasminece. Jasminum officinale, L. : segments of the flower 
 left, in the contorted aestivation, which however not unfrequently 
 passes over into the imbricated aestivation. Jasminum hirsutum, 
 Hoffmsgg. : segments of the flower predominantly right, in the 
 contorted aestivation. 
 
 91- 
 
 Oleacecs. Fraxinus heterophylla, Vahl: fruit slightly right 
 during the ripening. 
 
 92. 
 ApocynacecK. Segments of the flower wound in the bud, in 
 
298 M. WICHURA ON THE WINDING OF LEAVES. 
 
 certain species right, in others left. Alphonse DeCandolle* 
 has used the direction of the rolled buds in the descriptions of 
 the generic characters. His very accurate statements are made 
 use of in the following summary : 
 
 1. Parsonsiea, Alph. D.C., and Echitece, Don: seeds with a 
 coma above. Segments of the flower left in the bud. The 
 genera Neriandra, Alph. D.C., and Ecdysanthera, Hook., form 
 exceptions with right-wound segments. Since, however, there 
 has not yet been any possibility of examining their seeds, it is 
 doubtful whether they actually belong here. 
 
 2. Wrightiea, Don : seeds with a coma below. Segments of 
 the flower right in the bud. 
 
 3. Alstonieae, Don : seeds with a coma above and below. 
 Direction of the segments of the flower variable. In Blaberopus, 
 Alph. D.C., they wind to the right ; in Adenium, Roem. et Schult., 
 left. The genus Alstonia, R. Br., includes several species with 
 left- wound segments of the flowers, and one other species in 
 which the segments wind to the right, Alstonia scholaris, 
 R. Br. 
 
 4. Plumeriece, Alph. D.C. : seeds naked, two separate ovarian 
 segments of the flower wound to the right in the bud in most of 
 the genera. They are wound to the left only in Kopsia, Blume ; 
 Odontadenia, Benth. ; Malonetia, Alph. D.C. ; Anisolobus, Alph. 
 D.C., and Thyrsanthus, Benth. 
 
 5. Willughbiea, Alph. D.C. ; Carissece, Alph. D.C. : seeds 
 naked ; ovary simple ; segments of the flower right in the bud. 
 
 A few other movements of winding of the parts of the flower 
 occur more isolated : 
 
 Thevetia neriifolia, Juss. : funnel-shaped corolla with five- 
 toothed border. In the bud it is weakly folded towards the left, 
 and at the same time wound heliacally in the opposite direction, 
 that is, to the right. Echites longiflora, Desf. : the left-rolled 
 buds slightly twisted together to the left above. For Christya 
 spinosa, Ward et Harvey ; Strophanthus divergens, Graham, 
 and Str. dichotomus, D.C,, see 42, 43. Parsonsla spiralis, 
 Wall. ; P. oblonga, Wall. ; P. Cumingiana, Alph. D.C. ; P. heli- 
 candra, Hook, et Arn. : filaments left. Nerium Oleander, L. : 
 the filiform points of the anthers left. 
 
 * DeCandolle, Prodr. Syst. Natural viii. 317-489. 
 
M. WICHURA ON THE WINDING OF LEAVES. 299 
 
 93. 
 
 Asclepiadece. Segments of the flower predominantly left in 
 the bud, I have not observed exceptions to this rule myself. 
 But according to Decaisne*, the segments of the flower are 
 wound to the right in the genera Secamone ; Toxocarpus, W. 
 et A. ; Calostigma and Oxypetalum, R. Br. Microloma sagittata, 
 R. Br. : points of the flower-buds twisted to the right. Pergu- 
 laria accidens, Blume; P. edulis, E. M.: buds twisted to the 
 left at the points, the unfolded segments of the flower wound 
 to the left. Diplolepis Menziesii, R. et S. ; Oxypetalum ripa- 
 rium, H. B. K. : segments of the flower left after the flower 
 opens. Probably the genus Pycnoneuron, Dene., also belongs 
 here, since Decaisne says of it, " Laciniis post anthesin superne 
 dextrorsum contortis," i. e. according to our terminology, to the 
 le/t-\. 
 
 94. 
 
 Gentianece. For the winding of the stem-leaves of Chironia 
 see 46. Segments of the corolla of all the Gentianere, per- 
 haps with the exception only ofMenyanthes and Villarsia, wound 
 in the bud, and everywhere toward the left. The tubes of the 
 corollas of Gentiana are in addition laid in folds towards the 
 right in the bud. Chironia, Erythr&a, Plocandra palustris, 
 Griseb.; PI. Krebsii, Griseb. ; Sabbatia corymbosa, Ell.: de- 
 hiscing anthers to the left. Lisianthus uliginosa, Griseb. : style 
 left. Sabbatia corymbosa, Griseb. : style right. 
 
 95. 
 
 Labiates. Burgsdorfia montana, Hort. Bot. Berol. : stem-leaves 
 to the left at the base. Hyssopus lophanthus, L. ; Lophanthus 
 chinensis, Benth. : tube of corollas right. The revolution 
 amounts to about ^ so that the lip of the flower is carried to 
 the upper side. Bentham, in his description of the Labiatas, 
 explains this resupination incorrectly, by a revolution of the 
 flower-stalk J. 
 
 96. 
 
 Cordiacece. Cordia Geraschanthus, L. ; C. complicata, Ruiz; 
 C, alliodora, Ruiz : segments of the corolla left in the bud. 
 
 * D.C. Prodromus, 1. c. 501, ,504, 580, 581. f Ibid. p. 582. 
 
 J Tom. i. Introduction, p. xxiii. 
 
300 M. WICHURA ON THE WINDING OF LEAVES. 
 
 97. 
 
 Asperifoliae. Pulmonaria maritima, and all the species of 
 Myosotis I am acquainted with : segments of the corolla left in 
 the bud. Trichodesma africanum, Lehm. ; Tr. indicum, R. Br. ; 
 Tr. zeylanicuitij R. Br, : points of the anthers wound together 
 towards the left. 
 
 98. 
 
 Convolvulacecs. The corollas of Convolvulus and the allied ge- 
 nera are folded to the right and at the same time wound helia- 
 cally to the left in the bud. See 92. for the contrast in Thevetia 
 neriifolia, Juss., with which, in other respects, the folding and 
 twisting of the corolla before the opening of the flower exactly 
 agree. 
 
 99. 
 
 Hydrophyllea. Nemophila, all the species as yet known to 
 me, and Hydrophyllum virginianum : segments of the corolla 
 right in the bud. 
 
 100. 
 
 Scrophularinece. Pedicularis : the tube of the corolla under- 
 goes a revolution to the left, seldom exceeding ^, during the 
 opening of the flower, whereby the parts of the flower acquire 
 an oblique position. Apparently this revolution commences at 
 that part of the tube which is continued above into the lower 
 lip. This is always most strongly twisted, and it may be clearly 
 detected that the winding of the part of the tube of corolla be- 
 longing to it commences independently and alone before the flower 
 opens, and in a comparatively very young condition. Then, as the 
 part of the tube belonging to the upper lip remains in its position, 
 and the part belonging to the lower lip undergoes a curvature 
 to the left, the left side of the lower lip becomes approximated 
 to the upper lip in the same degree as it is removed from it on 
 the right. The result of this is, that the left side of the lower 
 lip becomes more intimately blended with the upper lip than 
 the right, hence the sinus which separates the upper and lower 
 lips on either side is always cut in deeper on the right than on 
 the left. Pedicularis palustris, L. ; P. asplenifolia, Florke ; P. 
 canadensis, L. ; P. contorta, and P. lanceolata, MX., are species 
 
M. WICHURA ON THE WINDING OF LEAVES. 301 
 
 in which all these phaenomena are exhibited with especial clear- 
 ness. Probably traces of them might be discovered in all spe- 
 cies. Anthocercis littorea : the narrow, lanceolate segments of 
 the corolla to the right after the flower is open. 
 
 101. 
 
 Acanthacece. Gendarussa orchioides, N. ab E. : stem -leaves 
 to the left. Peristrophe caulopsila, N. ab E. ; P. Kotschyana, 
 N. ab E. ; P. speciosa, N. ab E. ; Hypoestes aristata, R. Br. ; 
 H. polymorpha, N, ab E. : tube of corolla right. 
 
 102. 
 
 Primulacea. Lysimachia punctata, Wall. : sepals convoluted 
 to the left at their tops in the bud. Lysimachia, Lubinia, Ana- 
 galliS) Cyclamen, Trientalis, and Samolus littoralis, R. Br. : 
 segments of corolla left in the bud. Cyclamen europceum, L. ; 
 Lysimachia punctata, Wallr. : segments of the corolla right after 
 the flower is open. 
 
 103. 
 
 Cesneracece. Dorcoceras hygrometrica, Bge. : the walls of 
 the dehiscent capsule left. 
 
 104. 
 
 Sapotacea. Mimusops dissecta, Spr. (Herb. Gen. Berol.) : the 
 linear-lanceolate acuminated segments of the flower left, after 
 the flower is open. 
 
 105. 
 
 Myrsinaceff. Segments of the flower frequently wound in 
 the bud, and then constantly towards the left. " Lobis petalisve, 
 aestivatione varia, saepius sinistrorsum contorta/' says Alph. 
 DeCandolle* of this family. According to his observations, 
 Ardisia Pickerinyia, Torr. & Gray, has right-wound petals. The 
 segments of the calyx are said to wind to the right. I have not 
 investigated this family myself. 
 
 * Prod. viii. p. 75. 
 
302 M. WICHURA ON THE WINDING OF LEAVES. 
 
 106. 
 
 dEgiceracea. "Calyx 5-partitus, lobis sinistrorsum imbricato- 
 convolutis ...... Corolla ...... lobis aestivatione sinistrorsum imbri- 
 
 cato-convolutis." Alph. DeCandolle*. This family also is un- 
 known to me. 
 
 107. 
 
 Ebenacea. Segments of the flower left, in the bud, in all 
 species. 
 
 108. 
 
 Epacridece. On the winding of the stem-leaves ofAndersonia 
 prostrata, Sond., and Sprengelia incarnata., see 45 ; also, as to 
 the winding of the segments of the flower in this family, and in 
 the family of the Rosaceae, Caryophylleae, Hypericineae, Gera- 
 niaceae, Lineae, Oxalideae, Cistineae, Sauvagesieae, Malvaceae, 
 Sterculiaceae, Byttneriaceae, Clusiaceae, and Euphorbiaceae. 
 
 109. 
 
 Ericaceae. In the great majority of species of the genus 
 Erica the segments of the limb of the corolla are wound, and 
 constantly towards the left. 
 
 HO. 
 Saxifrages. Vahlia capensis, Thunb. : stem-leaves left. 
 
 HI- 
 
 Ranunculacea. Nigella sativa, L. ; N. damascena, L. ; N. 
 hispanica, L. : style to the left. Clematis azurea : appendages of 
 the carpels wound to the right. 
 
 
 
 Papaveracece. Platystemon californicum^ Benth. : style of the 
 ripening fruit left. 
 
 H3. 
 
 Mesembryanthecs. Mesembryanthemum aureum, L. : petals 
 convoluted to the left in the bud. 
 
 * Prod. viii. p. 141. 
 
M. WICHUBA ON THE WINDING OF LEAVES. 303 
 
 Silenece. Dianthus diutinus, Kit. ; D. atrorubens, All. ; D. tri- 
 fasciculatus, W. et K. (fig. 9) : stem-leaves left. Dianthus, Gyp- 
 sophila, Saponaria, Vaccaria, and generally, apparently, in the 
 Silenece with only two styles : petals to the left in the bud. 
 The peculiar twisting of the petals in a direction contrary to 
 that of the spiral of the sepals peculiar to the Silenete with three 
 or five styles, and already spoken of above, does not present itself 
 distinctly in all the species. Thus, for example, I observed in 
 Lychnis chalcedonica, L., Silene Armeria, L., and many other 
 Silenea, that the left- wound buds predominate; while, if the 
 petals of every bud were wound contrary to the direction of the 
 spiral of the sepals, right- and left-wound flower-buds ought to 
 exist in equal numbers, since the leaf- and consequently the 
 sepal-spirals of each pair of opposite branches of the inflorescence 
 of this family are wound in contrary directions. Such examples 
 of plants with prevailing but not exclusively left- wound flower- 
 buds form the transition from the Silenece with petals wound 
 contrary to the direction of the sepal-spiral, in which, there- 
 fore, on account of the antidromy of opposite flower-branches, 
 right- and left- wound flower-buds alternate regularly, to the 
 two-styled Silenea with only left-wound buds. Agrostemma 
 Githayo is a plant in which the sepal-spiral may be particularly 
 easily made out from the imbrication of the teeth of the calyx, 
 and I recommend it for investigation of this point. It shows 
 the law prevailing in the three- or many- sty led Silenea with 
 almost unalterable regularity. Dianthus deltoides, L. ; Lychnis 
 coronaria, Lam. ; L. chalcedonica, L. ; L. Flos-cuculi y L. ; Silene 
 repens, Patrin., &c. : style right. 
 
 11.5. 
 
 FranJceniacea. Frankenia campestris, Schauer. ; F. pulveru- 
 lenta, L. : tube of calyx right. 
 
 
 
 Loasece. Loasa lateritia, Gill, et Hook. : capsules mostly 
 wound to the right, more rarely to the left. Blumenbachia in- 
 signis, Schrad. : capsules right. 
 
304 M. WICHUEA ON THE WINDING OF LEAVES. 
 
 117. 
 
 Sterculiacea. For Helicteres, and its contorted aestivation, 
 see 16. Helicteres guazumcefolia, H. et B. : fruits of the two- 
 flowered cymes probably wound towards opposite sides on ac- 
 count of the antidromy of their leaf-spirals. I have only been 
 able to examine the fruits of this one species, but think the rest 
 would exhibit a similar character. 
 
 H8. 
 
 Xanthoxylece. Ailanthus glandulosus, Desf. : fruits wound to 
 the right (fig. 3) at the tips. 
 
 119- 
 
 Oxalidea. Besides the winding of the petals in the bud, 
 already mentioned, I observed a very distinct and constant 
 winding of the stem-leaves to the right, in a species of Oxalis 
 which was cultivated in 1848, in Decker's Nurseries at Berlin, 
 under the doubtful name of Oxalis palmata. 
 
 120. 
 
 Onagrariece. (CEnotherea] : segments of the corolla left in 
 the bud. Lopezia : the upper part of the solitary existing sta- 
 men to the right. 
 
 121. 
 
 Combretacece. Combretum purpureum, Vahl : petals in the 
 bud left. 
 
 122. 
 
 Philadelphea. Philadelphus coronarius, L. ; P. Gordonianus, 
 Lindl. : petals in the bud right. Philadelphus hirsutus : petals 
 in the bud left. 
 
 123. 
 
 Melastomacete. Petals in the bud left, probably in all the 
 Melastomaceae. For the winding of the sepals and anthers in 
 Arthrostemma Humboldtii, see 47. 
 
 124. 
 
 Myrtacea. Callistemon and Metrosideros : stalks of the stem- 
 leaves about towards the left. For the winding of the stem- 
 leaves of Eucalyptus and Melaleuca, see 45 and 46. 
 
M. WICHURA ON THE WINDING OF LEAVES. 305 
 
 125. 
 
 Papilionacea. Dillwynia eritifolia, Sm.; D. glaberrima, Sm. ; 
 D. parvifolia, R. Br. ; D. rudis, Sbr. ; D. laxlflora, Benth. ; 
 D. pinea, Sbr. ; Ccelidium ciliare, Vogel ; Amphithalea, Eckl. et 
 Zeyh. : stem-leaves right. Trifolium circumdatum, Kze. ; Tr. 
 resupinatum, L. : the resupination of the flowers of these two 
 plants is produced by a half revolution of the tube of the co- 
 rolla toward the right. Similar windings of the tube of the 
 corolla are met with also in Trifolium fragiferum. But the 
 winding is much slighter here, inconstant in its direction, and 
 amounts scarcely to a quarter of the circumference. Medicago : 
 the legumes of most of the species wind to the left. The fol- 
 lowing have right-wound legumes : M. tuberculata, Willd. ; 
 M. tribuloides, Lam.; M. rigidula, Lam. ; M. striata. For Me- 
 dicago littoralis, Rohde, see 36*. Sesbania cegyptiaca, Pers. : 
 the very long linear articulated pod left. Crotalaria retusa, L. ; 
 Cr. verrucosa, L. ; Cr. ovalis, Pursh ; Cr. quinquefolia, L. ; Cr. 
 carinata, Steud. : the dried-tip style right. The twisted styles 
 of some species of Lathyrus, e. g. L. rotundifolius s Willd., and of 
 PhaseoluSy follow the same direction. The revolution, however, 
 begins here in the bud, and is imparted to the keel tightly en- 
 closing the style, the former thus likewise acquiring an heliacal 
 winding. Petalostemon candidum, MX. : drying-up style wound 
 in many flowers to the right, in others to the left. Dalea bra- 
 chyptera, Kunze : style slightly left. For the revolution of the 
 phyllodia in Acacia micracantha 9 Desf., Fam. of Mimosece, 
 see 45. 
 
 XIV. Cause of the Curvature of Wound Leaves. 
 
 126. 
 
 The curvature of the winding leaf depends either on an un- 
 equal tension of its margin in relation to the axis, or on an in- 
 equality of length of its two surfaces. The specific gravity, 
 which otherwise is certainly to be enumerated among the causes 
 of the curvature of the leaf, comes but little or not at all into 
 
 * See also A. Braun on "Regular Revolutions in the Vegetable Kingdom," 
 Flora, 1839, i. 313, in which the heliacal winding of the legumes of the species 
 of Medicago is described correctly according to DeCandolle's method of de- 
 fining it. 
 
 SCIEN. MEM, Nat. Hist. VOL. I. PART IV. 20 
 
306 M. WICHURA ON THE WINDING OF LEAVES. 
 
 account in the winding leaf. For since the weight always 
 draws downward, if it were this that compelled the winding 
 leaf to curve, the latter must, in every half revolution, according 
 as it turned this or that side downward, curve, alternately, at 
 one time to this, at another to that side. It must consequently 
 see 31. turn sometimes one, sometimes the other side to 
 the interior of the helix. But it is just one peculiarity of wind- 
 ing leaves, that they always turn one side to the interior of the 
 helix, no matter how many revolutions the leaf may make. The 
 cause of the curvature can only be sought therefore in the 
 leaf itself, and not in any one-sided force acting upon it from 
 without. 
 
 127. 
 
 The unequal tension of the margins of a leaf in relation to the 
 axis, and the parts lying next to it, is produced by the revolu- 
 tion around the axis. It lies in the nature of the curve, as a 
 bent line, that the heliacally wound lateral parts of a leaf with 
 a straight axis must have passed over a longer course, and there- 
 fore must be longer, than this axis itself, which travels through 
 about the same distance by a straight path. If a leaf winding 
 round its straight axis is unrolled, the margins are thrown into 
 waves and folds, and thus present clearly to the eye the over- 
 plus of longitudinal development which was expended in the 
 formation of the heliacal curve. But such forms of the leaf are 
 comparatively rare. In the great majority of leaves the borders 
 and axis exhibit a perfect uniform longitudinal development, and 
 no obstacle is offered to their parts being spread out in one plane. 
 Hence it is clear, that, when such a normally formed leaf be- 
 comes affected by revolution of its axis, its first effort must be 
 directed to supply the want of predominant longitudinal develop- 
 ment by elongation of the lateral part of the leaf. The extensi- 
 bility of vegetable fibre is certainly capable of this up to a certain 
 point. Vegetable fibre is, however, at the same time elastic, and 
 thus the force which expands it is met at once by another force, 
 which strives to draw it back again into its former dimensions. 
 Only a part of this form can be taken off by the curvature of the 
 axis, since the two forces do not act in diametrical opposition, 
 but obliquely against each other. Another part of the force 
 
M. WICHURA ON THE WINDING OF LEAVES. 30? 
 
 remains over, and draws the leaf downward from the point where 
 the revolution of the axis takes place. The results are various, 
 according as the leaf is strong enough to oppose a resistance to 
 the pressure burdening it, or not. In the former case the re- 
 volution of the axis is limited to the degree admitted by the 
 extensibility of the fibre, which is so slight that the movement 
 of winding possible under such conditions will remain almost 
 invisible to our eyes. But if the leaf gives, and curves, there 
 arises, as we have seen above, 30, from the combination of 
 revolution of the axis and curvature, a new movement, which is 
 very essentially distinguished from mere revolution of the axis, 
 insomuch that now all parts of the leaf, its axis included, take 
 share in the heliacal winding around an ideal axis lying outside 
 the substance of the leaf. The contrast which appears between 
 axis and margins in a leaf wound round its own axis, is com- 
 pletely removed, and it no longer requires a predominating 
 longitudinal development of the lateral parts of the leaf to render 
 the heliacal winding possible. In this way the obstacles opposed 
 to revolution of the axis are removed by the curvature of the 
 leaf, after the revolution of the leaf having itself previously pro- 
 duced the curvature. The two movements then act as reciprocal 
 causes, and the result is that revolution of the axis and curvature 
 of the leaf are mostly combined ; winding leaves not curled are, 
 on the contrary, very rare. 
 
 128. 
 
 At the same time it is true, that in the curled winding leaf, 
 two other contrasts, likewise accompanied by an unequal tension 
 in the substance of the leaf, present themselves in the place of 
 the contrast between the axis and margins of the leaf, removed 
 by the curvature. Under supposed equal longitudinal develop- 
 ment of both surfaces of the leaf, in the first place, the surface 
 turned outwards must be rendered more tense, since it describes 
 a larger arc, than the surface turned to the interior of the helix, 
 and this in the greater proportion as the leaf is thicker. Se- 
 condly, from mechanical causes which it would occupy too much 
 space to discuss here, one margin of the leaf, namely in left- 
 wound leaves with the upper face turned inwards, and in right- 
 wound leaves with the lower surface turned inwards, the right 
 
 20* 
 
308 M. W1CIIURA ON THE WINDING OF LEAVES. 
 
 margin as seen from below ; and in left- wound leaves with the 
 lower face turned inwards, and also in right- wound leaves with 
 the upper face inwards, the left margin must be rendered more 
 tense than the other, and this the more, the broader the leaf is in 
 proportion to its length. But the leaves which, as we here pre- 
 suppose, are curved by the pressure arising from the revolution 
 of the axis, cannot, for that very reason, be very broad or very 
 thick, since otherwise they would not give to the certainly very 
 slight pressure acting upon them. The very slight breadth, in 
 proportion to the length, is, as already remarked, a characteristic 
 peculiarity of all winding leaves. The unequal tension of the 
 surfaces and borders of the leaf caused by curled wound move- 
 ment, is consequently really so inconsiderable, that it is doubt- 
 less mostly compensated by the extensibility of vegetable tissue. 
 
 129. 
 
 The unequal length of the two surfaces, and the curvature of 
 the leaf caused by this, is the effect of a hygroscopic difference 
 of these surfaces, on account of which their relative lengths alter 
 in the drying-up of the leaf: whether this happens through an 
 elongation or shortening of one of the two faces, I must leave 
 undecided, from the want of accurate observations. This hy- 
 groscopic curvature of the leaf acquires especial importance in 
 regard to the revolution of the axis, when this requires a curva- 
 ture of the leaf to bring it to light, not being strong enough in 
 itself to produce this. The heliacal winding of the leaf is thus 
 first made possible through the addition of the hygroscopic cur- 
 vature to the revolution of the axis. Since the former, however, 
 depends upon the desiccation of the leaves, only making its ap- 
 pearance towards the end of the life of the plant, the revolution 
 of the axis in this case makes its first appearance in the latest 
 stages of growth as the last expression of an expiring vitality. 
 
 130. 
 
 Such winding leaf-structures, which are very remarkable, like 
 the awns of the Grasses, the appendages of the carpels of the 
 Geraniece, the carpels of Dorcoceras hygrometrica, Bunge, &c., 
 possess the property of recovering the originally equal length of 
 
M. WICHURA ON THE WINDING OF LEAVES. 309 
 
 their two surfaces, in contact with moisture. The curvature is 
 thus removed, and in the same proportion as the leaf stretches 
 itself straight, the heliacal winding only possible under the hy- 
 pothesis of a certain degree of curvature, is unrolled. As soon as 
 the leaf dries arid again curls, under the influence of the again in- 
 creasing difference of length of its two surfaces, the heliacal wind- 
 ing is restored. The whole of this movement depends therefore 
 upon a play of mere mechanical forms, totally distinct from that 
 originally causing the revolution of the axis. They nevertheless 
 have been confounded in many cases. The heliacal winding of 
 awns, the fruit-stalks of Mosses, &c., has been generally looked 
 upon as an effect of their hygroscopic nature, without separating 
 the two different movements contained in it, and the mechanical 
 explanation of the whole process following as a consequence of 
 this view, may have contributed to have drawn away the atten- 
 tion of botanists from the striking physiological phenomenon of 
 revolution of the axis, which is exhibited so clearly in these very 
 structures. 
 
 XV. Causes of the Revolution of the Axis. 
 
 131. 
 
 To cause the revolution of the axis, we must imagine a force 
 circulating in a direction perpendicular to the longitudinal di- 
 rection of growth. It is an immediate revelation of the vital 
 force acting in the interior of the plant, and therefore stands in 
 the closest connexion with the growth as its regular expression. 
 Such a connexion may be detected in some cases by the cir- 
 cumstance, that in the plants mentioned in 45, the lateral 
 direction in which solitary leaves follow one another in a spiral 
 line, acts in determining the direction of the heliacal winding of 
 the leaf, in other cases it becomes observable in the remarkable 
 inverse proportion between transverse growth and revolution of 
 the axis, through which leaves in which the growth in breadth 
 has become developed in the angle-nerved venation, exhibit no 
 revolution of the axis, while parallel-nerved leaves in which 
 growth in breadth is deficient, develope that force rotating at 
 right angles to the direction of longitudinal growth, requisite for 
 the revolution of the axis. That this inverse proportion between 
 growth in breadth and revolution actually does exist, and that 
 the parallel- nerved leaves do not exclusively wind, merely 
 
310 M. WICHURA ON THE WINDING OF LEAVES. 
 
 because the usually narrow form opposes the least resistance to 
 the rotating force, perhaps present as in other leaves and only 
 restrained in its effects, is testified by the occurrence of angle- 
 nerved leaves of very long and narrow shape, which, never- 
 theless, do not wind. So far as regards length and breadth of 
 their parts, these stand in exact agreement with parallel-nerved 
 leaves ; indeed the lobes and pinnae into which they frequently 
 divide are sometimes much finer and more delicate than those 
 of winding parallel- nerved leaves. If, therefore, the forces 
 moving the parallel-nerved leaves were active in these, they 
 ought to exhibit the same effect, and it should produce an heli- 
 acal winding of the angle-nerved leaves in a determinate direc- 
 tion. But we do not see this; proof, consequently, that the 
 angle-nerved leaves are devoid of the rotating force, and that 
 the cause of the absence of revolution of the axis from them 
 does not arise from their merely opposing a greater resistance 
 than the parallel-nerved leaves to a rotating force existing in 
 them. Hence latitudinal growth of the leaf and rotation of the 
 axis are really mutually exclusive. When the former is deve- 
 loped, the latter is wanting, and so it seems to follow from this 
 that one and the same force lies at the foundation of both, 
 manifesting itself either in the transversely directed activity of 
 growth, or, when this is absent, in a lateral movement of the 
 leaf. 
 
 132. 
 
 While attention was paid merely to winding stems, it was 
 possible to suppose the object of this motion to be that of ob- 
 taining attachment to outw r ard objects. We are now aware 
 that a great proportion of winding stems, and winding leaves 
 in general, never coil round a support nor contribute to the 
 fixing of a plant. The latter, therefore, appears to be merely 
 an isolated application of the movement of winding in the 
 oeconomy of nature, and we must confess that we are totally 
 ignorant of its peculiar relation to the vital purposes of the in- 
 dividual, or the propagation of the species. This movement is, 
 at the same time, the most frequent of all those detected in the 
 outward organs of plants. The number of plants with winding 
 stems alone, particularly if we include the winding flowering 
 stem of the Monocotyledons and the winding fruit-stalks of the 
 
M. WICHURA ON THE WINDING OF LEAVES. 311 
 
 Mosses, is very considerable. Still larger is the number of the 
 plants with winding leaves enumerated in 55-125. And it 
 must not be forgotten that, according to 127? there must be 
 movements of rotation which escape notice on account of their 
 slight degree ; as indeed, for example, the rotation of the indi- 
 vidual leaflets which causes the contorted aestivation is so slight, 
 that it would be wholly concealed were not its traces preserved 
 by the regular overlapping of the margins. In the face of such 
 considerations, the character of external fixedness, which it has 
 hitherto been customary to connect with the conception of a 
 plant, vanishes, and we rather arrive at the conviction that 
 plants, too, possess, in the rotation of the axis, a motion peculiar 
 to them, which reveals itself everywhere that the moving force 
 has not been already exhausted in latitudinal growth, and there 
 found a different expression proportionate to it. 
 
 EXPLANATION OF PLATE IX. 
 
 Figs. 1 & 2. Each of these figures represent horizontal sections of two penta- 
 phyllous buds rolled to opposite sides. 
 
 Fig. 2. is intended to render clear the direction followed in the rotation. If 
 the line a b is to be removed, by a rotation round the point x, the 
 point of section of the axis of the leaf, into the situation marked by 
 the line c d, this takes place by a rotation which is continued to 
 things standing outside the rotation, as the arrows indicate, in No. 1. 
 from left to right, in No. 2. from right to left. The comparison of 
 the two figures 1 & 2, shows us that the aestivation fig. 1 . No. 1 . is 
 produced by the former movement, the aestivation fig. 1 . No. 2. by 
 the latter. Therefore, in logical application of the Linnaean termi- 
 nology of the aestivation, we call the arrangement fig. 1. No. 1. 
 right-wound, that of fig. 1. No. 2. left-wound. 
 
 Fig. 3. Fruit of Ailanthus glandulosa, L., wound to the right at the summit. 
 
 Fig. 4. No. 1. Fruit of Erodium Cicutarium, L., on an enlarged scale. The 
 appendages of the carpels are wound to the left round the carpophore. 
 No. 2. A carpel separated from the carpophore, also magnified ; the 
 appendages wind to the right. 
 
 Fig. 5. Leaf of an dvena, which is wound to the right below, and to the left 
 above. 
 
 Fig. 6. Branch of Chrysocoma Linosyris, L. Leaves wound to the right in 
 agreement with the direction of the leaf-spiral. 
 
 Fig. 7. Branch of Acacia micracanfha, Desv. Phyllodia wound to the left in 
 correspondence with the direction of the leaf-spiral. 
 
 Fig. 8. A left-wound and at the same time strongly curved leaf of Chrysanthus 
 angustifolia. 
 
 Fig. 9. Branch of Dianthus trifasciatus, W. & K., with left-wound leaves. 
 
 [A. H.] 
 
312 A, KROHN ON THE DEVELOPMENT OF THE ASCIDIANS. 
 
 ARTICLE X. 
 
 On the Development of the Ascidians. By A. KROHN. 
 
 [From Miiller's Archiv, 1852-1853.] 
 
 IN setting forth the results of my observations on the develop- 
 ment of the Ascidians, it is nowise my intention to lay before 
 the reader a connected account of all the appearances which 
 they present. Considering the earlier works in this department, 
 I shall endeavour to exhibit only the most important steps, and 
 in connexion therewith, as occasion may serve, to consider some- 
 times one, sometimes another organ, whose mode of development 
 may possess a special interest. I will premise here that the 
 facts I am about to communicate all relate to the development 
 of the Phallusia mammillata of Cuvier, and have been obtained 
 by the employment of artificial fecundation *. By this method 
 I have succeeded in following out their progress step by step 
 for three months, until the young Ascidians had attained the 
 size of a line or more. I commence with the unfecundated 
 ovum, inasmuch as its structure is distinguished by many im- 
 portant peculiarities. 
 
 1. Unfecundated ovum. The fully formed ova which fill the 
 oviduct consist, most externally, of a villous investment, within 
 which is the proper vitellary membrane. Under the vitellary 
 membrane there lies a glassy layer, in which roundish green 
 structures of a peculiar kind are imbedded, and which surrounds 
 the colourless yelk. The germinal vesicle and spot, both of 
 which are still readily distinguishable in the ovarian ova, are 
 already wanting f. 
 
 The investing membrane is thin, and beset superficially by 
 
 * The first successfully conducted attempts to fecundate the ova of the 
 PhallvsicB were made by Von Baer. 
 
 f The same structure is exhibited by the unfecundated ova of the Phal- 
 lus^ in general, as well as by those of the genus Clavelina. 
 
A. KROHN ON THE DEVELOPMENT OF THE ASCIDIANS. 313 
 
 numerous short, blunt-pointed processes. Each villus consists 
 of an aggregation of round, transparent, vesicles or cells, without 
 nuclei. 
 
 The glassy layer which lies upon the yelk is altogether homo- 
 geneous, but is otherwise remarkable from the first- mentioned 
 structures which are imbedded in it *. Each of these bodies 
 consists of densely aggregated vesicles or cells. We find these 
 structures sometimes solitary, sometimes united into groups of 
 different forms and sizes, in the glassy layer. The latter is, 
 however, nothing else than the primitive rudiment of the 
 mantle, which is already present in the unfecundated ovum of 
 the future Phallusia. The green structures, which persist un- 
 changed during the whole of larval life, change, after metamor- 
 phosis has taken place into the granules, which are contained 
 in abundance in the mantle of the adult animal. This layer 
 has already been recognized by Milne-Edwards (Obs. sur les 
 Ascid. composees des Cotes de la Manche, p. 26. pi. 4. 
 fig. 4) in the ova of Amouroucium proliferum, and has been 
 quite justly interpreted to be the future test (Mantelschicht), 
 as the following passage especially shows, p. 36 : " La couche 
 tegumentaire (L e. the test) est dans le principe la couche gela- 
 tineuse (glassy layer) qui dans Pceuf revet en dehors la masse 
 vitelline." According to this, however, Kolliker's view (An- 
 nales d. Sc. Nat. 1846, t. v. p. 218), that the test in Amourou- 
 cium Nordmanni and Aplidiwn gibbulosum, arises only after the 
 cleavage of the yelk, is confuted ; and I cannot doubt that it 
 is this layer, which has been regarded by Van Beneden (Mem. 
 sur 1'Embryogenie, &c., des Ascidies, in the Mem. de PAcad. 
 Roy. de Bruxelles, t. xx. p. 37) as the albumen of the egg, 
 although Milne-Edwards expressly draws attention to the pos- 
 sibility of falling into this error. 
 
 2. Yelk Cleavage and Embryo. Without doubt the ova, as 
 Cuvier already supposed, and Von Baer has endeavoured to 
 demonstrate with more conclusive arguments, are fecundated in 
 the so-called cloaca, into which the seminal canal and the ovi- 
 
 * The remarkable green or yellowish green colour of the ovarium and of 
 the oviduct, in many Phallusice, arises entirely from these green structures. 
 When the latter are colourless, as in Clavelina for example, the parts in 
 question are without colour. 
 
314 A. KBOHN ON THE DEVELOPMENT OF THE ASCIDIANS. 
 
 duct open, close by one another. Since, however, in the Phal- 
 lusia, we never meet in this cavity with ova whose development 
 has commenced, as is commonly the case in the compound 
 Ascidians, perhaps nothing is more probable than that the ova 
 are cast forth soon after fecundation, and that their development 
 begins first, external to the parent. 
 
 The cleavage of the yelk commences, about two or three 
 hours after the semen has been brought into contact with the 
 ova. It proceeds for the first stages, at least, in a very regular 
 progression. I believe I have made out with tolerable certainty 
 that every cleavage mass, after the completion of its division, is 
 surrounded by an excessively delicate membrane. On the ad- 
 dition of water impregnated with acetic acid, we see this invest- 
 ment gradually raised up from the vitelline contents, which con- 
 tract into a smaller space, as an independent membrane. As 
 regards, however, the clear vesicular nuclei within the cleavage 
 masses, I believe I have arrived at the result, that they dis- 
 appear when a new division impends, and only after this has 
 come to an end do they reappear again, newly formed. In their 
 place there may be observed, in any yelk-mass about to divide, 
 a very peculiar arrangement of the vitelline molecules. The 
 latter are in fact disposed in thick striae, \vhich radiating from 
 the centre, are directed on all sides towards the lighter periphery 
 of the mass, and seem to spread from two centres of irradiation. 
 When, after the completion of division, the nuclei appear within 
 the new cleavage masses, the radiate striation has also dis- 
 appeared, and the yelk-granules are seen, lying close to one 
 another in the masses, without any definite arrangement. All 
 these appearances agree, however, with that later view of the 
 cleavage process, which was first taken by Riechert (Miill. 
 Archiv, 1846, p. 196). 
 
 The glassy layer upon the yelk, which we have just described 
 as the original rudiment of the test present in the unfecundated 
 ovum, takes not the smallest share in these thorough changes 
 of the yelk; it remains, without undergoing any alteration, 
 closely apposed to the vitelline membrane. 
 
 Before the expiration of the first four-and-twenty hours after 
 fecundation, we find in most ova that the embryo has assumed 
 its well-known cercarian form, with a more or less developed 
 
A. KROHN ON THE DEVELOPMENT OF THE ASCIDIANS. 315 
 
 tail. It is invested by the test which contains the, as yet 
 wholly unchanged, green structures, and is separated from 
 the vitellary membrane by a space filled with fluid. The 
 substance of the body and of the tail consists of cells ; at least 
 the latter are clearly distinguishable on the surface of these 
 parts. The cells are polygonal, contain granules, and in addi- 
 tion a central nucleus ; the axis of the tail is composed of larger 
 rectangular cells, simply disposed in series, one behind the 
 other, and also provided with a central nucleus, thereby attain- 
 ing a transversely striated or articulated appearance *. 
 
 There are various views as to the mode in which the tail is 
 formed. According to Milne-Edwards the peripheral portion of 
 the embryo, as it were in one piece, becomes constricted off 
 from the body. Kolliker follows this opinion when he states 
 that the tail grows out, not in the manner of a process, but, as 
 a determinate portion of the blastema, becomes separate all at 
 once in its whole length from the body. According to Van 
 Beneden, on the other hand, the tail buds forth as a short 
 process, which elongates by degrees. I can but confirm this 
 last opinion. In fact, according to my observations, the tail 
 appears in the younger embryos, very short and thick in rela- 
 tion to the body, although it is already slightly curved. After- 
 wards it becomes continually longer and more slender, embracing 
 the body in a continually larger arc, until at last it has grown up 
 to such an extent that its terminal portion enfolds the anterior 
 part of the body of the embryo. 
 
 A short time before the completion of the development of the 
 larva, the tail undergoes remarkable changes. The axis becomes 
 hollowed out, its whole cellular substance disappearing into a 
 canal. This excavating process, which is accompanied by a 
 contemporaneous liquefaction of the cell-contents, appears 
 always to proceed from the two walls which are in contact with 
 one another, of every pair of cells, and indeed in many places at 
 the same time, extending further and further, until at last, by 
 the flowing into one another of the separate cavities, the canal 
 in question is formed through the whole length of the axis. In 
 
 * This composition of the axis of the tail of large rectangular cells was first 
 demonstrated by Kblliker in the embryos of Amour oiiclum Nordmanni and 
 Aplidium (1. c. p. 221, fig. 43). 
 
316 A. KROHN ON THE DEVELOPMENT OF THE ASC1DIANS. 
 
 the meanwhile, however, the superficial layer of the axis of the 
 tail, which is composed of smaller cells, appears to have become 
 metamorphosed into a muscular layer consisting of longitudinal 
 fibres, by whose energy those active movements of the tail ex- 
 hibited by the young larvae after birth are performed. At 
 present these movements are manifested only by the occasional 
 twitches of the tail, which become more and more frequent in 
 the last period of larval development. In consequence of these 
 twitchings, the viteliine membrane eventually becomes torn, and 
 thus, towards about the thirtieth hour after fecundation, the 
 larva escapes. 
 
 One point must not escape notice ; with regard to those two 
 dark pigment spots which have been observed on the back of 
 the larval embryos, but which have been, as it seems to me, too 
 hastily taken for eyes. At first we see only a single pigment spot 
 exactly in the middle line of the back. Behind this and more 
 laterally a second, larger one, soon becomes visible (PI. XII. B. 
 fig, 1. e). I have never succeeded in discovering any refractive 
 medium in these pigment spots ; but I could, as little, satisfac- 
 torily interpret the optical expression of the immediate neigh- 
 bourhood of these spots, which I have endeavoured to repro- 
 duce truly in the figure just cited. This much is certain, that 
 both pigment spots, which in the larva remain always separate 
 from one another (see fig. 2), approach quite closely in the 
 course of metamorphosis and, during the development of the 
 young Ascidian, continue to appear for a long time as an appa- 
 rently single mass, lying close below the nervous ganglion. In 
 the end, however, this mass breaks up into the two original 
 portions, or even into many pieces, and so passes into the 
 current of the blood, in which they may be seen driven up and 
 down for a time, until at last they are wholly dissolved and dis- 
 appear. This long continuance of the pigment spots, extending 
 far beyond larval life, appears to me not to be in accordance 
 with the function ascribed to them. For the present, therefore, 
 their true import remains doubtful. 
 
 3. Larva (see fig. 2). The body of the hatched larvag is 
 elongated, has two slightly convex, lateral surfaces and is pro- 
 vided at its anterior extremity with three very short processes, 
 as it would seem excavated into suckers. Two of these lie 
 
A. KROHN ON THE DEVELOPMENT OF THE ASCIDIANS. 31? 
 
 higher and laterally opposite to one another ; the third, which 
 springs from the middle of the anterior part of the body, is more 
 inferior. By means of these prolongations, which are seen as 
 conical processes even in the embryos (fig. 1. c, c), the larva 
 attaches itself to some appropriate place in order to go through 
 its metamorphoses. These processes, first seen by Milne- 
 Edwards, and first justly interpreted by him, and whose ex- 
 istence has been confirmed by Kolliker, have been, it would 
 seem, quite overlooked by Van Beneden. 
 
 With regard to the portion of the test which invests the tail, 
 it may be stated here, that it terminates in a fin-like, expanded, 
 probably horizontal appendage. The true composition of this 
 appendage is, at first, the more difficult to perceive, as it can 
 rarely be got under the microscope with its whole breadth at 
 once. Therefore, it seems to me, as if the flabelliform process, 
 into which, according to Van Beneden, the test of the tail in 
 the larvae of Ascid. ampulloides (1. c. pi. 2) runs out, were a 
 similar appendage, only more strongly developed, and seen from 
 the edge. 
 
 4. Metamorphosis and Development. The changes which the 
 tail undergoes, immediately after the attachment of the larva, 
 have been already described by Milne-Edwards in a manner, in 
 the main, in accordance with nature. According to this observer, 
 the contractile central portion or axis of the tail becomes gra- 
 dually retracted from its investment and passes at last into the 
 body of the larva, so that the investment remains behind, as an 
 empty sheath, which subsequently falls off. Milne-Edwards' 
 investigations give no account of the further fate of the retracted 
 axis. 
 
 According to what I have seen, the loosening and retraction 
 of the axis of the tail, which, as we saw, sinks deep into the 
 body of the larva, are only the forerunners of the retrogressive 
 metamorphosis which it soon undergoes. Immediately after 
 its retraction, we find the tail still in good preservation in the 
 posterior division of the now enlarged body. Here it lies rolled 
 up spirally into a coil, which may be pressed out of the body or 
 unrolled by the use of carefully increased compression. Whilst 
 the development of the young Ascidian commences, the coil 
 breaks up first into many closely appressed lobes, and now 
 
318 A. KROHX OX THE DEVELOPMENT OF THE ASCIDIANS. 
 
 withers away by degrees in such a manner that the lobes 
 become smaller and fewer, until they are but minute remnants. 
 In the end these also disappear. When the coil begins to 
 diminish, it occupies, as before, the whole posterior division of 
 the body of the developing Ascidian ; but subsequently, when 
 it has become visibly smaller, it lies more on the left side near 
 the oesophagus (PL XII. B. fig. 3). 
 
 From what has been said then, it results, that Van Beneden 
 has not rightly comprehended the appearances during the extri- 
 cation of the tail from its investment, since he considers this act, 
 which for the rest his figures depict very well, to depend upon 
 an absorption of the tail. Had Van Beneden recognized all the 
 phases of the retrogressive metamorphosis of the tail, he could 
 not long have remained in doubt as to the true nature of the 
 undefined organ (/. c. pi. 3. figs. 11 & 12 e) met with in the 
 posterior part of the body of Ascidia ampidloides during the first 
 periods of development. He would have at once seen it to be 
 the coiled-up and already lobulated tail. 
 
 Very soon after the tail has been withdrawn into the body, 
 and the latter has thence even to some extent increased in size, 
 the three processes of attachment of the larva disappear, while 
 in the meanwhile the mantle of the developing animal is fastened 
 to the ground by its whole lower surface. From the mass of 
 the body, and indeed from the midst of the abdominal surface, 
 three processes of another nature now grow forth, and pene- 
 trating deeper and deeper into the mantle, attain its surface. 
 These hollow processes are the first indications of that dichoto- 
 mously branched vascular system, with distinct walls, which pe- 
 netrates the mantle of all Phallusia*. These processes are soon 
 seen to become longer and to divide dichotomously into the first 
 branches, whose extremities appear clavate; the dichotomous 
 branching goes on further and further, and the terminal branches 
 
 * According to Kolliker's more exact investigations (I. c.), this vascular 
 system consists everywhere of double vessels, which running close together 
 ramify correspondingly, and accompany one another to the very finest ter- 
 minal ramifications, when a mutual anastomosis takes place. According to 
 my observations, this anastomosis occurs in such a manner that the terminal 
 twigs of the two vessels bend round into one another like a loop. All these 
 observations are also, as we shall see, perfectly confirmed by the study of deve- 
 lopment. 
 
A. KROHN" ON THE DEVELOPMENT OF THE ASCIDIANS. 319 
 
 are always found enlarged in the mode described. In young 
 developing Ascidians which have fixed themselves normally, that 
 is, by their whole under surface, we see subsequently, when the 
 vessels of the test have branched out extensively, that all the 
 branches and twigs extend perpendicularly and radially, on all 
 sides, towards the circumference of the mantle. In those indivi- 
 duals, on the other hand, which have been unable to find any, or 
 no convenient, place for fixing themselves, while still larvae, but 
 whose development nevertheless goes on*, the original vessels of 
 the test, namely the three above-mentioned processes, as well 
 as their subsequent ramifications, take the most various direc- 
 tions, curving downwards for the most part. It would seem, 
 therefore, as though a speedy termination were put to the further 
 ramification by the above-mentioned unfavourable circum- 
 stances ; such individuals probably die prematurely. 
 
 It is, however, so much the easier to mistake the true nature 
 of the vessels of the test, during the early stages, since even when 
 the heart has appeared and the circulation has become established, 
 we see not the slightest trace of any current of blood in them. 
 In addition, the mantle is so transparent that its contours are 
 easily overlooked, and the idea may readily arise, that the much 
 more sharply defined vessels extend beyond its boundaries, 
 w hereas they are invested by it. It is therefore difficult, at first, 
 to avoid considering the vessels of the test as stolons or runners, 
 by the aid of which the young Ascidian seeks to fix itself more 
 and more strongly to its residence. This view has the greater plau- 
 sibility because many \sridians (Cynthia papillata for example) do, 
 in fact, attach themselves to foreign bodies by means of branched 
 stolons ; however, the establishment of the circulation in these 
 vessels of the test at once releases us from this error. At first 
 one sees nothing but a column of blood containing merely a few 
 granules, irregularly oscillating. Afterwards, when the ramifi- 
 cations have extended, the blood is more rich in granules and 
 the circulation goes on more rapidly ; the oscillation is converted 
 
 * A yet more striking example how little the course of development allows 
 itself to be arrested, is presented by certain larvae which have been unable to 
 burst their envelopes, but whose metamorphosis has nevertheless commenced, 
 as we see by the coiled tail and the commencing formation of the vessels of the 
 test. 
 
320 A. KROHN ON THE DEVELOPMENT OF THE ASCIDIANS. 
 
 into a regular current ; at the same time the, originally, quite 
 simple main trunks and branches have become double, whilst their 
 globularly enlarged, terminal twigs, directed towards the peri- 
 phery of the mantle, are still simple tubes. In the larger vessels, 
 which accompany one another and branch out in common, just 
 as in the adult animal, the blood now streams in two opposite 
 directions, in the one vessel towards the periphery, in the other 
 towards the heart. Shortly before the division of the last branches 
 into the terminal ramuscules, we see these two streams pass into 
 one another by a loop ; on the other hand, in the terminal 
 branches no continuous current of the blood is as yet to be ob- 
 served; the blood-corpuscles indeed penetrate into them, but they 
 frequently stagnate and sometimes become excessively accu- 
 mulated. They are only occasionally seen to enter the current 
 and return in one or other of the streams we have mentioned. 
 All this continues until the doubling has extended as far as the 
 terminal twigs. The cause of the two opposite currents is 
 readily discovered, inasmuch as observation shows that each of 
 the double vessels opens into opposite ends of the heart. Since, 
 furthermore, the heart, even soon after its appearance, pulsates 
 periodically in two opposite directions, at every change, we see 
 the current of blood in each vessel reversed. 
 
 Van Beneden has described processes very analogous to the 
 rudiments of the vessels of the test, growing forth in the Ascidia 
 ampulloideSy soon after the retraction of the tail ; after a short 
 existence, however, they disappear. If these last processes are 
 identical with the vessels of the test of the developing Phallusice, 
 the latter statement contradicts the observations communicated 
 above. Ascidia ampulloides is very probably a Cynthia. The 
 cartilaginous test, the plaited respiratory sac, and the double 
 reproductive organs, arranged exactly as in the Cynthia, speak 
 for this view. In the mantle of the Cynthia, so far as I know, 
 no vessels have as yet been demonstrated. If they be absent, 
 then the processes indicated by Van Beneden must have some 
 other import ; if they be present, the statement that the pro- 
 cesses soon disappear is probably erroneous*. 
 
 * The budding vessels of the test will not easily be confounded with the 
 puzzling diverticula of the test, which, Proteus-like, sometimes protrude, some- 
 times are again retracted and disappear wholly, observed by Milne-Edwards 
 
A. KROHN ON THE DEVELOPMENT OF THE ASCIDIANS. 321 
 
 With respect to the first stages of development, I have not 
 obtained all the information I desired, on account of the many 
 difficulties in the way of a satisfactory examination. Never- 
 theless I will not hesitate to communicate, in a condensed form, 
 the observations which belong here, imperfect as they may be. 
 It will be observed that as regards many points, they harmonize 
 with the views of Van Beneden. 
 
 Soon after the three hollow processes, the rudiments of the 
 future vessels of the test, have appeared, we distinguish in the 
 body, besides those parts which belonged to the larva, viz. the 
 two pigment spots, now closely approximated, and the coiled tail, 
 a cavity which represents the future respiratory or gill-sac. 
 Immediately behind this appears the first indication of the ali- 
 mentary canal, which appears in the form of a canal, everywhere 
 of even diameter and bent round into the form of a loop. The 
 whole posterior division of the body is filled by the coil of the 
 tail. 
 
 Subsequently one may observe on the dorsal surface, on the 
 second layer of the body, which lies under the mantle and is 
 clearly distinguished, three apertures, over which the mantle, 
 still imperforate, passes. The one lies exactly in the middle 
 at the anterior extremity of the body, the two others are alto- 
 gether lateral and diametrically opposite to one another, in the 
 middle portion of the body. The anterior, somewhat larger, 
 corresponds with the future ingestive or respiratory aperture ; 
 the two posterior are intended to take the place of the future 
 cloacal aperture, which arises, at a much later period, by their 
 coalescence. At this time the nervous ganglion also has become 
 developed, and may be readily distinguished as an elongated 
 structure in the middle of the dorsal surface and close above 
 the two pigment spots. Near it we see the first indications of 
 the future interwoven muscular cords of the body ; the abdo- 
 minal furrow is already indicated; the nutritive canal has 
 become further developed ; it lies now, for the most part, above 
 the respiratory sac and describes a curve, commencing at the 
 bottom of the latter and passing round to the immediate neigh- 
 bourhood of the left excretory aperture. Three divisions may 
 
 during the development of Amouroucium proliferum, and which he has fully 
 described. 
 
 SCIEN. MEM. Nat. Hist. VOL. I. PART IV. 21* 
 
322 A. KROHN ON THE DEVELOPMENT OF THE ASCIDIANS. 
 
 be distinguished in it, the oesophagus opening into the respi- 
 ratory sac, the stomach, and the intestine. 
 
 Soon after this there appear in the wall of the respiratory sac 
 the first respiratory or gill-clefts (stigmates branchiaux, M. Edw.), 
 in the form of four round apertures, provided with vibrating 
 cilia. Their distribution is perfectly symmetrical, each pair 
 lying upon the two opposite sides of the respiratory sac, one 
 close behind the other and below their respective excretory 
 apertures. Van Beneden (1. c. p. 44. pi. 3. fig. ll/".) has ob- 
 served these apertures and discerned their true import. 
 
 The heart appears to be formed last of all. It represents at 
 first, a very short sac lying on the right side, near the stomach, 
 or rather near the abdominal furrow, distinguishable by its un- 
 dulating but, at present, very slow movement. It is distended 
 with blood-corpuscles, which are driven alternately hither and 
 thither. 
 
 Before long the test gives way, over the three apertures of the 
 body, whose margins have, in the meantime, become notched, and 
 thus the young Ascidian enters into relation with the external 
 world, since, from this time forth, it is enabled to take in nutritive 
 matter and the water necessary for respiration. Before this, 
 however, the second layer of the body on each side, in the entire 
 neighbourhood occupied by the two apertures of the gills, has 
 become detached from the respiratory sac, which elsewhere lies 
 in close apposition with it, in the form of an externally convex 
 roof. This roof therefore includes a cavity, which communicates 
 on the one hand, by means of the respiratory apertures with the 
 branchial sac, on the other by means of the corresponding ex- 
 cretory apertures, which are seated upon the summit of the roof, 
 with the exterior ; the terminal portion of the intestine, which 
 has in the meanwhile become longer, curves at this time round 
 the bottom of the respiratory sac upwards, and opens in the end, 
 by means of the anus into the left space above mentioned*. In 
 this way it becomes possible that the water drawn in through 
 the anterior aperture of the body into the respiratory sac, should 
 pass through the branchial apertures into the two spaces, and 
 become emptied out again through the excretory apertures, whilst 
 
 * We shall subsequently recur once more to these two spaces. 
 
A. KROHN ON THE DEVELOPMENT OF THE ASCIDIANS. 323 
 
 the undigested remains of the food merely pass into the left 
 space and are extruded through its aperture. 
 
 We soon see clearly that the heart pulsates more swiftly, 
 and in addition in alternately opposite directions, and that the 
 blood, which already had begun to oscillate in various parts of 
 the body, now follows a determinate, though very simple course ; 
 this consists of a dorsal and an abdominal current, united by two 
 transverse currents on each side, the one of which may be seen 
 round the anterior aperture of the body, the other within the 
 bridge formed by the wall of the respiratory sac between the two 
 respective branchial apertures. 
 
 . As regards the test, it has already been stated that the green 
 aggregated vesicles originally deposited in it become afterwards 
 changed into its granules; this change commences only sub- 
 sequently to metamorphosis, and consists in the green struc- 
 tures gradually losing their cellularity and becoming smaller, 
 less coloured, and more angular, and so by degrees assuming 
 their ultimate form. It is only at a later period that those 
 large, rounded, thin-walled cell-spaces appear, which, as is well 
 known, occupy, closely appressed, the substance of the mantle 
 in the full-grown animal (comp. Kolliker, /. c.}. At first their 
 number is but small, but afterwards they multiply, increasing 
 in size at the same time, so that in this way the finer structure 
 of the mantle becomes more and more perfect*. 
 
 In accordance with my plan I will now treat only of those 
 organs whose further development is either interesting in itself, 
 or has not yet been sufficiently investigated, and upon whose 
 structure the study of development is calculated to throw some 
 light. 
 
 We may consider, first, the respiratory sac, concerning the 
 minute structure of which, in the adult animal, the following 
 points may be called to mind. It is well known that its inner 
 surface is divided into rectangular compartments by longitudinal 
 and transverse ridges, which intersect one another at right angles. 
 It is, besides, beset with numerous ciliated papillae, one of which 
 
 * It is remarkable that the same metamorphosis of the green structures 
 occurs also in the test investing the tail, which has been left behind as an 
 empty sheath. 
 
 21* 
 
324 A. KBOHN ON THE DEVELOPMENT OF THE ASCIDIANS. 
 
 is placed at every crossing point of the ridges ; the bottom of 
 each compartment is pierced by from four to six narrow longi- 
 tudinal clefts, the branchial apertures (stigmates branchiaux, 
 Milne- Ed wards) , around whose edges is a fringe of numerous 
 vibratile cilia. The bridges between these clefts are hollow, and 
 receive the blood requiring aeration, brought to them on one 
 side by the ridges, which are also hollowed, and carried away, on 
 the other, after it has undergone the necessary change, to be re- 
 distributed by other ridges. The play of the cilia round the 
 edges of the clefts drives the fresh water, continually drawn into 
 the branchial sac, past the bridges. 
 
 As we know, however, the apertures lead into a large internal 
 space (chambre thoracique et cloaque, Milne-Edwards) between 
 the respiratory sac and the second layer of the body, which 
 opens externally by the excretory or so-called anal siphon. 
 
 Of all those parts which contribute to the complicated orga- 
 nization of the respiratory sac, the most important, that is, the 
 gill-clefts and the intervening bridges, are formed first ; for we 
 have seen the apertures appearing in the very earliest stages of 
 development, as two rounded openings on each side. It was 
 stated also that a current of blood was already established in the 
 bridges. For a long time the respiratory sac possesses only these 
 two pairs of apertures, which in the meantime elongate and be- 
 come more and more cleft-like. At last there appear two new 
 apertures on each side in the bridge between them, and soon after- 
 wards another is added behind the originally posterior cleft, so 
 that there are now altogether five openings. In this manner, 
 successively and in serial order, a multitude of openings soon 
 rapidly appear and pierce the two sides of the respiratory sac. 
 At first, a second series is formed close to and above the first, then 
 above this, a third and so more and more series, until the middle 
 line of the back is reached. In similar succession rows of aper- 
 tures appear, one below the other, between the first series and 
 the abdominal surface. Like the original openings, ah 1 these ap- 
 pear, originally, as small gaps beset with vibratile cilia, and during 
 their gradual enlargement undergo similar alterations in form, 
 becoming more and more lengthened into clefts. It is easily 
 comprehended that with the progressive increase of the respira- 
 tory sac, the number of the clefts also subsequently increases in 
 
A. KROHN ON THE DEVELOPMENT OF THE ASCIDIANS. 325 
 
 each series, and that new series continually appear between the 
 old ones. 
 
 Soon after the respiratory sac has become thus perforated in 
 its whole extent, we find the clefts, which previously had their 
 long diameters disposed transversely to the axis of the branchial 
 sac, arranged as in the adult animal with their long axes longi- 
 tudinal. Many of the papillae, covered with vibrating cilia, have 
 at the same time become developed, upon the inner surface of 
 the transverse and longitudinal bridges, between the clefts. The 
 blood streams rapidly and abundantly through all the bridges. 
 I have been unable to trace the development of the respiratory 
 sac any further. In its present, by 110 means complete, struc- 
 ture, however, it singularly resembles the respiratory sac of the 
 compound Ascidians. In this case we have again an example of 
 the often enunciated and repeatedly confirmed law, that the 
 higher forms of any given order of animals, at least as respects 
 particular organs, exhibit transitorily, relations of form and struc- 
 ture which occur permanently, that is, in the adult state of the 
 lower forms. 
 
 It will be recollected, that the three apertures of the body 
 which were at first covered by the test, had opened externally 
 after the appearance of the first gill-clefts and of the heart, in 
 consequence of which the young Ascidian was enabled to take 
 in nutritive matters and the water required for respiration. 
 These apertures now become prolonged into short projecting 
 tubes, the siphons. The aperture of the respiratory siphon, 
 which from the beginning surpasses the two posterior or excre- 
 tory siphons in circumference, soon appears fringed by eight 
 lobes, as in the adult animal. In all the siphons the circular 
 fibres, by whose action they are occasionally closed, may now 
 be very readily distinguished under the test. Externally, above 
 the circular bundles, there appear also a few longitudinally fibrous 
 bundles, processes of the muscular bundles which, already inter- 
 laced, are disposed over the second layer of the body. 
 
 The ultimate fate of the two posterior siphons is particularly 
 interesting, since, after persisting for a long time, they fuse 
 together into the single siphon present in the adult. In fact, 
 during the period in which the rapid multiplication of the 
 respiratory apertures in the branchial sac is taking place, we see 
 
326 A. KROHN ON THE DEVELOPMENT OF THE ASCIDIANS. 
 
 the two siphons gradually approximate towards the middle line 
 of the dorsal surface and at last come so close, that they are 
 separated only by a small bridge. When the respiratory sac is 
 completely perforated, this also disappears. Instead of the pre- 
 vious two excretory siphons, we now find a single one situated 
 exactly in the middle of the dorsal surface, close behind the 
 nervous ganglion ; its lip is already, as in the adult animal, pro- 
 vided with six lobes. 
 
 The presence of two excretory siphons, at an earlier period, 
 need not be at all surprising, if we recollect what has been pre- 
 viously stated respecting the two spaces which were formed over 
 the original gill-clefts ; it appears, in fact, to be almost a neces- 
 sary consequence. It was shown that the two spaces are deve- 
 loped by the raising up of the second layer of the body, in the 
 region of the apertures, from the respiratory sac, which is else- 
 where closely applied to it. This mutual separation goes on 
 to a greater and greater extent, during the further develop- 
 ment of new clefts in the respiratory sac. The consequence is, 
 that the boundaries of the two spaces extend further and further, 
 until at last, when the branchial sac is everywhere perforated, 
 they coalesce upon the dorsal side, and in this manner consti- 
 tute that inner space, between the branchial sac and the second 
 layer of the body, to which we have already referred in the adult 
 animal. When this has taken place there is no longer any need 
 of more than one siphon, and, in fact, the formation of the single 
 siphon is contemporaneous with that of the space in question. 
 
 I pass now to an organ, which in all the Phallusice surrounds 
 the whole nutritive canal, from the mouth to the anus, and 
 has the appearance of a compact honey-yellow mass, dotted 
 over with chalky-white points. By the majority of zoologists, 
 among whom we find a great authority (V. Siebold, Vergleichende 
 Anatomie, p. 269), this structure has been regarded as a liver ; a 
 view which, to me, appears so much the more doubtful, as an 
 organ which will subsequently be described, and which has 
 hitherto escaped notice, probably has a greater right to this title. 
 The organ now in question consists of obvious, clear, round, 
 tolerably dense walled vesicles, the supposed simple glandular 
 utricles in which the bile is prepared. 
 
 Every vesicle is apparently distended by a transparent fluid, 
 
A. KROHN ON THE DEVELOPMENT OF THE ASCIDIANS. 327 
 
 in the centre of which a solid concretion, in the form of a nucleus, 
 may be remarked. In the larger vesicles the white chalky 
 nucleus appears to be composed of two other rounded segments 
 in close apposition, in the smaller it is perfectly spherical*. 
 According to my observations the vesicles are all completely 
 unconnected with one another; sometimes I thought I could 
 make out a finely reticulated network upon the wall of some of 
 them, without being able to come to any clear conclusion upon 
 the matter. It is the more difficult to decide upon the purpose 
 of the whole structure, as its mode of development, as we shall 
 see immediately, does not throw the desired light upon it. One 
 is tempted to consider it as a purifying organ, a kidney, which 
 would agree very well with the deposits in the vesicles f In 
 that case, however, we ought to be able to discover excretory 
 ducts, of which I could find not the least trace. 
 
 The first indication of this organ appears when the residue of 
 the tail of the larva, reduced to a very few lobes, is rapidly dis- 
 appearing. Close to these lobes, we see first a small, round, 
 transparent vesicle, already precisely similar in structure to those 
 of the adult organ. The round chalk-white nucleus is already 
 visible in its centre. The vesicle now grows more and more, 
 and at last, when the residue of the tail disappears, it takes its 
 place close to the oesophagus on the left side. Subsequently a 
 second vesicle is formed close to the first, after this a third, and 
 so more and more, until the whole posterior space of the body 
 between the oesophagus, the stomach, and the intestine, is filled 
 up by a mass of such isolated vesicles, in every stage of develop- 
 ment. Afterwards vesicles are seen arising singly and remote 
 from the great mass near certain parts of the alimentary canal. 
 In a few vesicles the nucleus appears double, in others it is pro- 
 vided with the previously mentioned mass of laminated crystals. 
 Whether the vesicles arise at the same time with the nuclei, as 
 we have here described it, or whether the nuclei, as would seem 
 
 * In Phallusia monachus the round nuclei exhibit a close concentric stria- 
 tion, which seems to indicate a deposition in layers. In many vesicles a mass 
 of laminated or acicular crystals lies upon the nucleus ; sometimes one vesicle 
 or another contains, instead of the nucleus, a great prismatic crystal with 
 pyramidally pointed ends. 
 
 f Delle Chiaje (Animali invertebrati d. Sicilia citeriore, t. iii.), to whom these 
 concretions were not unknown, appears to hint at this interpretation. 
 
328 A. KROHN ON THE DEVELOPMENT OF THE ASCIDIANS. 
 
 to be theoretically more probable, are deposited from the fluid 
 of the vesicles at a subsequent period, must be left undecided. 
 I have but rarely seen the nucleus wanting at the first appear- 
 ance of the vesicles. The organ could be traced no further in 
 its development, which is, however, clear enough from what has 
 just been stated. 
 
 Finally, it only remains that I should describe an organ as yet 
 unknown, which is so hidden, as only to be partially visible in 
 the full-grown animal. It consists of a system of fine canals, 
 which are distributed over the whole intestine, commencing in 
 caecal extremities, which are partly cylindrical, partly, and for 
 the most part, enlarged or clavate, and often locally sacculated ; 
 these enter into manifold anastomoses with one another, and 
 thus enclose the wall of the intestine with a close network ; at 
 last they unite into twigs and branches. The canals are found, 
 most abundantly, within the strong projection which runs along 
 the inner surface of the intestine from the stomach almost to the 
 anus, and which is besides filled with the vesicles of the organ 
 which has been already described. The ramification of the 
 branches and twigs, which frequently, during their course, per- 
 form arched curvatures somewhat in the manner of the vasa 
 vorticosa of the eye, and in some places dilate into ampullae, is 
 dichotomous; the contents of the caeca and canals are pellucid. 
 So much for the relations of this organ in the adult animal ; 
 development affords us the following further information. 
 
 Very early, even before the appearance of the first gill-clefts 
 and of the heart, there appears at the beginning of the intestine 
 immediately behind the stomach, a cylindrical process, alto- 
 gether homogeneous, and with a somewhat enlarged, clavate, free 
 extremity, which passes transversely, on the left side, to the vici- 
 nity of the terminal portion of the intestine. Without percep- 
 tible alteration, this process continues slowly to grow, until at 
 last we see it divide at its extremity into many branches, which 
 pass to and embrace the intestine. 
 
 Very soon these branches also divide, dichotomously, into 
 twigs, which by their frequent anastomosis form a network enclo- 
 sing the intestine. In this manner the ramification proceeds, the 
 network upon the intestine becomes closer, and at last the caeca 
 above referred to make their appearance upon it. The branches 
 
A. KROHN ON THE DEVELOPMENT OF THE ASCIDIANS. 329 
 
 now exhibit their characteristically wavy course, and in some 
 places the ampulliform expansions. It is worthy of being re- 
 marked further, that at this time, when the organ, in fact, is but 
 sketched out in its first rudiments, the main trunk of the canals, 
 i. e. the original process, as well as its branches, are still homo- 
 geneous solid cords, whilst in the caeca and the twigs which have 
 anastomosed into networks, the wall and the cavity are already 
 distinguishable. 
 
 It results hence, that the organ which consists of branched 
 canals opens by means of an excretory duct into the intestine, 
 as an appendage of which it at first appears. Its whole struc- 
 ture would lead one to consider it to be a gland, whose secretion, 
 prepared in the caeca, would seem, if we may judge by the place 
 of insertion of the duct into the gland, to be accessory to diges- 
 tion. Whether the watery secretion is bile and the gland there- 
 fore is a liver, must for the present be left undecided. 
 
 EXPLANATION OF PLATE XII. B. 
 
 Fig. 1 . Embryo in a late stage. Two pigment spots already exist, a, body ; 
 b, commencement of the tail ; c, e, the two upper processes of attach- 
 ment of the larva commencing their development ; d, anterior pigment 
 spot ; e, posterior pigment spot. 
 
 Fig. 2. Larva lying upon its side, a, a, test with the imbedded and as yet un- 
 changed green structures ; &, b, axis of the tail ; c, c, hollow canal of 
 the axis; d, the fin-like horizontal appendage into which the test 
 covering the tail becomes expanded ; e, anterior pigment spot ; /, 
 posterior pigment spot ; g, upper right process of attachment ; h, 
 lower process of attachment. 
 
 Fig. 3. A developing Phallusia of the stage when the three apertures of the 
 body have become already elongated into very short siphons, a, re- 
 spiratory siphon wide open; b,b, the two posterior or excretory siphons 
 in their contracted state ; c, nervous ganglion with four nervous 
 trunks ; d, oesophagus ; e, stomach ; f, intestine (its terminal portion 
 curves round the bottom of the respiratory sac upwards towards the 
 left excretory siphon) ; g, coil of the larval tail breaking up into lobes 
 and disappearing ; h, h, k, h, the four first gill- apertures with their 
 intermediate bridges ; i, the dark, apparently single mass of pigment 
 under the ganglion ; k, abdominal furrow ; /, /, test. 
 
 [J. H. H.] 
 
330 KOREN AND DANIELSSEN ON THE 
 
 ARTICLE XL 
 
 Observations on the Development of the Pectinibranchiata. 
 By MM. KOREN and DANIELSSEN. 
 
 [From the Annales des Sciences Naturelles, t. xviii. No. 5, and t. xix.J 
 1. On the Development o/'Buccinum undatum, Linn. 
 
 ALTHOUGH, since we first made known our investigations 
 into the development of the Mollusca, in the Magazin for 
 Naturvidenskaberne, many remarkable memoirs have appeared 
 upon the same subject (those of Nordmann*, of Vogtf? of Qua- 
 trefagesj, of Loven, of Reid ||, and of Leydig^f), yet we think 
 it advisable to set forth our observations here in full, and we 
 trust that they will not be read without interest particularly 
 as we have been able, in two genera of Gasteropods, to follow 
 step by step the development of the embryo from its first 
 appearance to its complete formation, and as we shall have to 
 bring forward facts new to science. 
 
 On the 1st of March, 1851, we procured many oviparous 
 capsules of Buccinum undatum. It is well known that these 
 capsules, spherical or ovoid in form, are most usually found united 
 into racemes nearly as large as the fist. They are attached to 
 various bodies, such as rocks, bits of old wood, marine plants, 
 &c. In many of these racemes, the capsules contained incom- 
 plete young, in others ova. We possessed then all the materials 
 required for our researches. To judge from the internal condition 
 
 * Versuch einer Monographic von Tergipes Edwardsii. 
 
 f Recherches sur I'Embryogenie de I' Action (Annales des Sciences Naturelles, 
 3rd ser. t. vi. 1846, p. 1). 
 
 % Annales des Sciences Naturelles, 3rd ser. t. iv. p. 33. 
 
 Bitrag til Koennedomen om Utwecklingen of Mollusca Acephala lamelli- 
 branchiata (Kongl. Vet. Akad. Handl. 1848). 
 
 || Ueber die Entwickelung der Eier der Mollusca nudibranchiata (Froriep's 
 Jahresberichte, Januar 1850). 
 
 ^f Ueber Paludina vivipara (Zeitschrift filr wissenschaftliche Zoologie. 
 Leipzig, 1850). 
 
DEVELOPMENT OF THE PECTINIBRANCHIATA. 331 
 
 of the ova and from other evidence which we have obtained, it 
 would appear that Buccinum undatum lays its eggs from the 
 beginning of January to the end of April. 
 
 Many oviparous capsules were opened, and their contents 
 subjected to microscopical examination. Each capsule enclosed 
 a limpid pellucid viscous liquid, resembling white of egg; in 
 this viscous humour and at the bottom of the capsule there lay 
 a large number of ova (6-800), which could with difficulty be 
 detached from one another ; each egg was composed of a delicate 
 transparent membrane (chorion), in the interior of which was 
 another, still more delicate, enveloping the yelk. The latter, 
 spherical in shape, was composed of a viscous fluid, in which 
 was dispersed a multitude of rounded granules, variable in size 
 and of a clear yellow colour (PI. X. fig. 2). No trace of either 
 germinal vesicle or germinal spot was visible ; the diameter of 
 the ovum varied between 0'257 and 0*264 of a millimetre. 
 
 On the 8th, 13th, 15th and 20th of March we re-examined 
 capsules of all the racemes ; the ova had remained, to our great 
 astonishment, spherical and without division*. 
 
 On the 24th of March the ova were still undivided, but in- 
 stead of being scattered as before, they had approximated to one 
 another. The chorion had begun to disappear ; the larger por- 
 tion of the yelk was diffused (Detail epanchee), and invested 
 by the viscous albuminous fluid which surrounded the vitelline 
 membrane. Some days afterwards, the ova had become agglo- 
 merated into a single mass, which at its surface was divided into 
 many portions, in which each ovum could be distinguished by 
 the naked eye. In general the number of the ova constituting 
 each of these portions varied from six to sixteen. 
 
 On the 29th of March again, we examined many capsules ; 
 the isolated groups were more sharply defined and each mass 
 had become ovoid or reniform ; it was observable also that these 
 groups were united together. 
 
 On the 1st of April we examined many capsules; one of 
 them enclosed twelve embryos ; they were ovoid or reniform, 
 and provided with two rounded lobes (vela) and a foot (figs. 3. 
 4 c & 5 e.). The fluid contained in this capsule was as clear as 
 
 * We have at times, in a few ova, seen a small conical eminence upon the 
 vitellus. 
 
332 KOREN AND DANIELSSEN ON THE 
 
 water and perfectly fluid, so that the embryos could easily be 
 extracted from it. In another capsule there were but six em- 
 bryos, four of which were well formed. 
 
 We began then to form a conception of the import of all these 
 facts ; but they seemed to us to be so extraordinary, that for a 
 long time we did not venture to put confidence in our observa- 
 tions so different were these results from all that had hitherto 
 been seen with respect to the development of Mollusks, and even 
 from all known physiological phaenomena. But the attentive 
 study of what went on under our eyes at last cleared away all 
 our doubts, and led us to dispute a law generally admitted and 
 based upon a great number of facts. In fact, we had before us 
 a mode of development which required for its proper under- 
 standing much new investigation ; and it appeared to us to 
 be indispensable to follow out these singular phaenomena in 
 neighbouring genera, in order to see if, towards the limits of this 
 zoological group, we should find them disappearing ; an anticipa- 
 tion which, as we shall see by and by, has been fully justified. 
 
 But let us first trace out these phaenomena in the Buccinum, 
 and we shall find them surprising enough ; for we shall look 
 in vain in a fecundated ovum, for any of those changes which 
 in ordinary cases take place during its development, in virtue 
 of the well-known law of yelk-division. We see no grooving 
 no cell appears ; in a word, the interior of the ovum remains 
 without alteration ; on the other hand, external to it we observe 
 active alteration. The excessively viscous albuminous fluid 
 collects and, so to speak, glues together the ova, which were 
 primarily separate, uniting them into bunches ; subsequently 
 the mass in which they were immersed, from being viscous, be- 
 comes as liquid as water ; and it is then that we first perceive 
 traces of activity in the ovum itself. Its external membrane 
 bursts in certain places the yelk becomes diffused, and a mem- 
 brane, destined to circumscribe the developing individual, is 
 produced around each bunch of ova ; between these bunches 
 we see many isolated ova, which seem excluded from this organic 
 process which gives rise to embryos. We do not know if these 
 isolated ova die at once, or undergo a further imperfect develop- 
 ment ; but in any case they are beings, whose existence is but 
 ephemeral. As soon as the grouped ova are invested by their 
 
DEVELOPMENT OF THE PECTIN1BRANCHIATA. 333 
 
 membrane, the formation of the embryo begins ; a very clear, 
 finely granular and viscous liquid is deposited at first on the 
 external surface of the ovum. In this plastic mass we see, in 
 some localities, cells developed, in others muscular tubules, ac- 
 cording to the nature of the organ which is to be produced ; 
 thus, the first signs of activity visible about the ova, after they 
 are laid, are observed in the very viscous albuminous mucus 
 which surrounds them, and this activity is manifested by the 
 mere union of a certain number of ova into more intimate rela- 
 tions. We imagined at first, that these phasnomena of agglo- 
 meration might represent yelk-division ; but we soon gave up 
 this idea, which seems to us altogether incorrect*. Besides, the 
 development of Pur 'pur a lapillus, which we have subsequently 
 examined, and in which division and the phaenomena of agglo- 
 meration go on at the same time, has also contributed to our 
 rejection of this notion. We come therefore to the conclu- 
 sion, that yelk-division is not always indispensable for the 
 production of the embryo ; but the fact of the agglomeration of 
 some fifty or more perfectly formed ova, into a single individual, 
 is certainly strange enough. Where does the formative principle 
 exist? Is it enclosed in an isolated ovum? Or is it extended 
 over the whole mass ? and is it the common power which be- 
 comes then the organizing force of the substance ? We have 
 seen the isolated ova undergoing a certain amount of develop- 
 ment, but the being which results from them is very incomplete 
 and becomes very rapidly destroyed. It would seem to want 
 the materials requisite for its permanent existence. We shall 
 return to this subject in treating of the development ofPurpura 
 lapillus, and we shall confine ourselves here to adding, that this 
 
 * In publishing here the observations of MM. Koren and Danielssen, which 
 are highly interesting in themselves, apart from the interpretation which may 
 be put upon them, we consider ourselves bound to remark, that the rounded 
 masses of vitelline matter, regarded by these authors to be simple ova, seem to 
 us to be merely vitelline spheres, whose utriculiform envelope presents a little 
 more consistence than ordinarily, and that therefore the aggregation from whence 
 the body of the embryo arises, is the result of the grouping together of the 
 vitelline spheres of a single ovum, and not the product of the union of many 
 primitively distinct ova. What these authors remark with respect to the phaeno- 
 mena of yelk-division, which are also sometimes observed in these spheres, 
 would in nowise oppose this interpretation. (Note by M. MILNE-EDWARDS.) 
 
334 KOREN AND DANIELSSEN ON THE 
 
 mode of development appears to us to be of great physiological 
 importance and will assuredly be confirmed by further obser- 
 vations. With regard to the number of ova which are grouped 
 together for the formation of a single embryo, there is consider- 
 able variation, and it seemed to us to be the greater, the greater 
 the number of the ova in the same capsule. In the mean, each 
 capsule contains from six to sixteen embryos ; however, we have 
 found as many as thirty- six. The more ova there are in a capsule, 
 the more of them there are in each mass, whence we sometimes 
 meet with embryos which have at their first appearance a very 
 considerable size, attaining in fact as much as 1^ millimetre. 
 The number of ova united into one embryo varies from 40 to 
 60 ; we have often, however, met with as many as about 130. 
 
 Gray long since observed*, that a capsule enclosing more than 
 a hundred ova yielded only four or five embryos. The English 
 physiologist explains this fact by the law of atrophy, that is to 
 say, by supposing that the great increase of some ova hinders the 
 development and ultimately effects the destruction of the others. 
 It remains to be seen whether Gray deceived himself, or whether 
 it is we who have fallen into error. We believe that he was on 
 the right track, but did not attain to the exact truth. 
 
 After having seen that the ova group themselves together, to 
 form the embryo, and become coated by a delicate and trans- 
 parent pellicle, we now proceed to explain the manner in which 
 the various organs make their appearance. The first step is 
 the exudation of a clear, finely granular substance over the 
 surface of the ova, which then begin to appear more trans- 
 parent. We perceive in this mass, a multitude of cells which 
 continually multiply ; it then takes on a distinct form and be- 
 comes bilobed (fig. 4c). These lobes are gradually provided 
 with cilia, and the first movements are exhibited. The foot, 
 which is formed in a corresponding manner, appears as an 
 eminence, distinct from the remainder of the body, and pre- 
 senting cilia ; the embryo then turns upon itself in an extremely 
 slow manner (fig. 5e). Scattered cirrhif now make their ap- 
 * Annales des Sciences Naturelles, 2 Ser. torn. vii. p. 375. 
 f Sars drew a distinction between the long cirrhi which are found on the 
 lobes and the cilia, and proposes to call them natatory hairs (Svremmehoar). 
 Subsequently many authors have called them cirrhi, retaining the name of 
 cilia for the very short, fine hairs. 
 
DEVELOPMENT OF THE PECTINIBRANCHIATA. 335 
 
 pearance here and there upon the upper edges of the rounded 
 lobes, and in a short time spread over their whole surface 
 (figs. 5 & 6) ; the lobes are then rounded and provided with cilia, as 
 well as with cirrhi (fig. 15). After the formation of the lobes 
 and of the foot, we see a semi-transparent granular substance 
 between the grouped ova and the membrane which invests them, 
 exuding and becoming the rudiment of the mantle, covering 
 itself superficially with a membrane which occupies a greater or 
 less space and takes on a determinate structure (fig. 4). Sub- 
 sequently we observe, on the lowest part of the mantle, a hemi- 
 spherical transparent body a which is the rudiment of the shell 
 (figs. 5, 6, ?) The foot increases in size and takes on a more 
 rounded form, and at its base we distinguish early the two audi- 
 tory organs (figs. 7, 8, 9^) . They are constituted by two spherical 
 vesicles, pellucid as water, filled with a perfectly transparent 
 and colourless liquid, and early exhibiting a double contour. 
 Each vesicle encloses but a single otolith. When the animal is 
 placed under the compressorium these organs become very di- 
 stinct, and by increasing the pressure, each otolith readily be- 
 comes separated into four regular segments. The vibratory 
 movement which most authors have observed in these otoliths, 
 has not been observed by us in those ofBuccinum undatum, neither 
 have we been able to distinguish any cilia upon the internal 
 surface of the vesicle, although we have employed the strongest 
 magnifying powers. 
 
 The eyes probably appear at the same time as the auditory 
 organs, for we have never seen the latter without being able to 
 observe the former. Leydig has remarked, that the rudimentary 
 eye is a vesicle which exists at the root of the tentacles. We 
 have confirmed the exactness of this observation; the internal sur- 
 face of this vesicle is always provided with cilia (fig. 100). It is 
 filled with a liquid, enclosing a quantity of pigment-granules, of a 
 strong, clear yellow colour, which are invested by an excessively 
 fine pellicle (fig. 10 b). At this period the vibrating cilia com- 
 municate a rotatory movement to these granules. We have 
 been unable to distinguish any lens at this period ; it is only 
 subsequently developed. At the same epoch as that in which 
 the eyes appear, we also found the two conical tentacles and 
 the rudiments of the salivary glands ; the latter always make 
 
336 KOREN AND DANIELSSEN ON THE 
 
 their appearance as two pyriform organs, composed of rounded 
 cells (figs. 8 & 9h) ; their lower extremity is the thicker, and their 
 centre is filled by a mass of deeply coloured pigment-granules. 
 The keel- shaped heart appears at the same time, as well as the 
 mouth and the rudiments of the proboscis. Sars, Loven, Nord- 
 mann and Vogt have been unable to discover any heart in the 
 first periods of development, and we have ourselves sought it 
 in vain in many Nudibranchiate genera ; we are therefore led 
 to conclude that the first period of development passes by 
 without the existence of this organ. It is not the same with 
 the Pectinibranchiata, at least with Buccinum undatum and 
 Purpura lapillus. In these the heart has already appeared in 
 the interval between the twenty-third and the twenty-eighth 
 day. Grant* was the first to observe the heart in Buccinum 
 undatum, and to draw attention to its strong pulsations. To 
 the same observer we owe the discovery of the two rounded organs 
 provided with vibratile cirrhi upon the sides of the head, by 
 the aid of which the embryos move about in Purpura, Trochus, 
 Nerita, Doris, and Eolis. Subsequently, Lund, Sars, Loven, 
 Nordmann and other naturalists, have confirmed the exact- 
 ness of these observations. The heart lies upon the dorsal 
 side, a little to the left, is a little twisted and completely un- 
 covered at its first appearance ; for different organs which cover 
 it afterwards, such as the roof of the branchial cavity, are still 
 rudimentary. In the place where the heart is about to appear, 
 a grayish, transparent, finely granular mass, having a rounded 
 form, arises ; it is attached to the lobes and the foot, and pre- 
 sents no sensible movement. Soon, slight contractions are per- 
 ceptible ; the form becomes more and more marked, and at last 
 it resembles a great clear vesicle. Two or three muscular tubes, 
 of extreme delicacy, are now traceable upon its parietes and 
 effect its contractions. In this primitive state, the heart possesses 
 the form which it will subsequently retain (fig. 6e). In propor- 
 tion as its parietes increase in thickness and magnitude, the 
 muscular tubes are multiplied, trans verse tubes appearing and be- 
 coming filled with a transparent and colourless liquid (figs. 7? 8 
 & 9 e) ; we have often counted the pulsations, and have found 
 that their rate varies ; on the average, there were some forty to 
 * Edinburgh Philosophical Journal, 1827, vol.vii. p. 121. 
 
DEVELOPMENT OF THE PECTINIBRAXCHIATA. 337 
 
 fifty a minute ; they are not always regular and frequently 
 change their character; strong pulsations occur among the 
 weaker pulsations. It frequently happens that the heart sud- 
 denly ceases to contract, remaining at rest for some time ; and 
 it is nowise uncommon to observe strong pulsations succeeding 
 intervals of rest. The cavity of the primitive heart is cylin- 
 drical, and is divided by a single partition. Its parietes are 
 excessively delicate, very transparent, and refract light in an 
 altogether different manner from the other organs (fig. 8 e) ; we 
 have never met with any liquid nor with any cellular structure 
 in them. We have also observed similar muscular tubes in 
 the two rounded lobes*; but here we see that many are super- 
 imposed and frequently ramify. This branching becomes more 
 and more abundant as we approach the periphery of the lobes, 
 where the finer ramifications frequently interlace arid a muscular 
 network results (fig. 15 a, b] which serves to move the two rounded 
 lobes in all directions. It may be, that a vascular network 
 exists in some parts of this muscular reticulation, for little gra- 
 nules, refracting the light strongly, are to be met with dispersed 
 through the mass. Since the two distinguished French natu- 
 ralists, MM. Milne-Edw r ards and Valenciennes, have pointed 
 out the greater or less incompleteness of the vascular system of 
 Mollusks, it has appeared to us to be important to observe the 
 condition of the circulation in the young Buccinum, but not- 
 withstanding all our efforts, we have not been sufficiently for- 
 tunate to detect the slightest trace of a circulating current f. 
 
 We have already stated that the proboscis is one of the organs 
 that appears early ; it is recognizable by its cylindrical form and 
 
 * Leydig, /. c., describes the structure of the muscles of a great number of 
 Gasteropoda, and remarks that the result of his researches upon this subject 
 does not altogether agree with that at which MM. Lebert and Ilobin have 
 arrived. We believe that those of Leydig are the more exact in all essential 
 points, inasmuch as they agree better with our own observations. 
 
 f We cannot help remarking that there is something very anomalous about 
 this supposed " heart," and we would venture to suggest that its structure and 
 position indicate rather, that it is no heart at all, but a "contractile vesicle," 
 similar to that which exists in the corresponding locality in the pulmonate 
 Gasteropoda, and which, acting in concert with the caudal vesicle, performs 
 the functions of a heart before the true heart makes its appearance. See 
 Gegenbaur, Beitrdge zur Entwickelungsgeschichte der Land Gasteropoden, 
 Siebold und Koiliker's Zeitschrift, 1852. [T. H. H.] 
 
 SCIEN. MEM. Nat. Hut. VOL. I. PART IV. 22 
 
338 KOREN AND DANIELSSEN ON THE 
 
 by the strong muscular contractions which it presents. A little 
 later, the stomach and the oesophagus appear ; the latter pre- 
 sents itself under the form of a hollow cylinder attached to the 
 proboscis, and presenting upon its parietes, which are of excess- 
 ive thinness, a certain number of clear striae, the rudiments of 
 the future muscular tubes. As soon as the oesophagus becomes 
 free from the proboscis, it bends a little backwards and upwards, 
 running along the lower surface of this organ for a short distance ; 
 then, having undergone a flexion in the opposite direction, it 
 directs itself a little to the left to terminate in the slightly elon- 
 gated portion of the stomach (fig. 12 ). It is extremely difficult 
 to follow the early phases of the development of the oesophagus ; 
 for it is surrounded by the proboscis, whose parietes are both 
 thicker and more opake than its own ; in some places it is en- 
 tirely covered by it. It is for this reason, that we have been un- 
 able to determine if the oesophagus is formed, at once, in all its 
 length, or if a portion appears at first, and elongates until it be- 
 comes united with the stomach. The latter organ is found a 
 little to the left, and, at first, is almost spherical. It appears 
 to arise thus : a grayish semitransparent mass exudes from a 
 single yelk, soon becoming invested by a delicate pellicle, which 
 completely encloses this same yelk (fig. 9 m). This membrane 
 at first stretches upwards to become united with the oesophagus, 
 and afterwards downwards to give rise to the intestine, which 
 turns towards the right side of the body (fig. 110). It is by 
 reason of this origin that we see the stomach always filled, so to 
 speak, with yelk-granules, which are constantly agitated by the 
 vibrating cilia with which the parietes of the stomach are pro- 
 vided. These cilia are found, not only on the internal surface of 
 the latter organ, but we have also observed them in the oesophagus 
 and in some parts of the intestine. As we have been unable to 
 follow the intestine for more than a small portion of its course 
 (fig. 1 1 e), we have not made out the anus. 
 
 It is at this period that the first outlines of the nervous system 
 are distinguishable : they are two compact, ovoid and yellow 
 bodies (cerebroid ganglia), which surround the oesophagus ; and 
 about the same time, the rudiments of the two pedal ganglia, 
 placed side by side, having a strong yellow hue and more or 
 less ovoid in form, make their appearance. 
 
DEVELOPMENT OF THE PECTINIBRANCHIATA. 339 
 
 After the edges of the mantle have developed themselves into 
 a covering over the back of the animal, a cavity clothed with 
 fine cilia is formed, in which the heart and branchiae lie. The 
 first traces of branchiae which we observed were two indistinctly 
 marked bands arising from the edge of the mantle, and diverging 
 at intervals to unite again and so form loops. We have found, 
 at a more advanced stage, that these bands are tubes taking a 
 very sinuous course, whence they have a certain resemblance to 
 a corkscrew. These sinuosities were better marked above and be- 
 low than in the middle, where they were wider and more closely 
 appressed; an active ciliary motion was distinguishable upon their 
 internal edge (11 p). Loven has shown, in his excellent memoir 
 (op. cit.), that there is an extreme .resemblance, in respect of 
 development, between the Gasteropoda and Acephala ; he has 
 described the mode of formation of the branchiae in the latter, 
 and we have observed even that the production of these organs 
 takes place in a similar manner in Buccinum undatum and Pur- 
 pura lapillus. 
 
 About the period of the formation of the branchiae we ob- 
 served, below, at their union, a vesicle which is formed and de- 
 veloped like the heart. It is ovoid or slightly pyriform, ends 
 below in a very long tube which follows the course of the intes- 
 tinal canal, and eventually, like the latter, becomes lost in the 
 obscure mass of the yelk (11, 12 q). Its walls are thin, semi- 
 transparent, and provided with a multitude of varicose muscular 
 tubes which take a direction both longitudinal and transverse to 
 the vesicle. These tubes have smaller dimensions than those of 
 the heart, and for that reason it is necessary, in order to distin- 
 guish them readily with the microscope, to employ a much 
 higher power than that required to examine the muscles of the 
 heart. 
 
 The contractions of the bladder are strong, and take place 
 from above downwards, whilst the heart contracts from one side 
 to the other. 
 
 When this vesicle dilates it becomes filled with a clear liquid 
 in which a great number of obscure molecules are distinguish- 
 able. We can regard this organ as nothing but the kidneys. 
 
 The period for the development of new organs has now gone 
 by, but all those already formed, become gradually perfected. 
 
 22* 
 
340 KOREN AND DANIELSSEN ON THE 
 
 The head and the back of the animal are now distinct, and are 
 provided with fine cilia and with much elongated tentacles, re- 
 sembling cilia. The eyes are more conical, and their lenses are 
 distinctly perceptible. The buccal aperture appears in the form 
 of a transverse cleft. The proboscis is perfectly developed. The 
 tongue appears in it with its armature such as Lebert and Loven 
 have described. The salivary glands are very voluminous, and 
 their excretory canals may be readily traced passing along the 
 sides of the ossophagus. The siphon is already much developed, 
 and provided with cilia (fig. 13 g). The form of the foot is modi- 
 fied, being considerably elongated; in addition, two rounded 
 lobes have arisen in its upper part; its surface is ciliated all 
 over (11,12/). As regards its structure, the foot is composed of 
 a multitude of primitive muscular tubules some cylindrical, 
 others varicose running in all directions, without however 
 uniting into bundles. We have never been able to detect either 
 granules or cells in these tubes. 
 
 At this period the nervous system has become very distinct. 
 We see that the two ganglia placed at the sides of the oesophagus 
 (cerebroidganglia,ll,12j9,14/ > ) are united by a commissure; from 
 each of these ganglia a very thick commissure passes (12 q, I4i) 
 to unite them to the pedal ganglia (12r, 14#), which are ovoid, 
 with their small extremities turned towards the cerebroid ganglia, 
 and furnish a great number of branches for the foot, (fig. 14 /.) 
 
 We see besides, in the lobes of the foot, two smaller, also ovoid 
 ganglia (125, 14m) which send branches to the lobes, Two commis- 
 sures (14 m), unite them to the pedal ganglia: the cerebroid ganglia 
 distribute a nervous twig to each eye and to each auditory or- 
 gan (I4g&h). We have observed that one of the pedal ganglia 
 sends a nerve to the intestinal mass (fig. 14 p). 
 
 The description given by Cuvier of the nervous system of this 
 mollusk* differs in many points from what our observations have 
 shown us. It is certain, that the nervous mass which Cuvier 
 has called the cerebrum is a pedal ganglion ; for we have seen, 
 in the adult animal, that the true cerebroid ganglion which sur- 
 rounds the oesophagus, and which, without doubt, escaped his 
 notice, is situated above this latter ganglion. 
 
 * Memoires pour servir a V Histolre de VAnatomie des Mollusques. Paris, 
 817. 
 
DEVELOPMENT OF THE PECTINIBRANCHIATA. 341 
 
 The shell, which is membranous during the first periods of 
 the development of the embryo, excessively delicate and ovate 
 or reniform, subsequently takes on the form of that of the Nau- 
 tilus (fig. 1 1 a), but subsequently becomes, by degrees, more 
 ovoid. The calcareous particles then begin to be deposited in 
 considerable numbers, forming very obvious longitudinal and 
 transverse striae^ and the shell is much less transparent than be- 
 fore. However, it is still possible to distinguish the internal 
 organs : the heart and the bladder have divided into two cham- 
 bers, the upper of which is the smaller. When the auricle con- 
 tracts, the ventricle dilates, and vice versa. A very strong muscle 
 is also observable, arising from the internal surface of the shell 
 and passing to the foot (fig. 1 1 s) ; its office is to retract the ani- 
 mal into its shell. Finally, the liver appears upon the under 
 surface of the stomach ; it is ovoid, and is formed of a mass of 
 granules containing yellow pigment (fig. llr). On the inner 
 surface of the mantle a series of folds may be observed (feuillets 
 muqueuxy Cuvier), in which lie a mass of mucous crypts. 
 
 Subsequently the little animal continues to grow ; more and 
 more calcareous particles are deposited in the shell : the mantle 
 thickens, and it becomes almost impossible to distinguish the 
 internal organs. The two rounded lobes have disappeared, but 
 behind the tentacles we see a linear eminence indicating the 
 place they occupied. The shell has assumed a horn-yellow co- 
 lour; it becomes hard, brittle, and only semitransparent. It 
 was commonly in this state that the young left its capsule, after 
 a residence of at least eight weeks there, creeping around the 
 vessel in which it had been kept, with tentacles, foot, and siphon 
 protruded. The little whelks are now distinguishable from the 
 adults, only by their shell having not more than one or two 
 spiral turns. We may add, that we have found no traces of 
 generative organs in these young. The ova, grouped together 
 in considerable numbers, occupy the posterior part of the shell. 
 
 2. Pur pur a lapillus. 
 
 The ovigerous capsules are not unlike a little flask whose 
 rounded end is directed upwards and its delicate neck, by the 
 extremity of which it is attached to stones or other bodies, down- 
 wards (PL XI. fig. 1). Each capsule is hermetically closed, and 
 
342 KOREN AND DANIELSSEN ON THE 
 
 contains a transparent, pellucid, viscous liquid, like the vvhite of 
 egg investing a mass of ova (60 or more) . 
 
 A number of the ova were placed under the microscope, after 
 freeing them from the viscous humour in which they had been 
 enclosed, and we saw that they possessed a delicate chorion, a 
 vitelline membrane, and a yelk consisting of a liquid, with many 
 contained granules. We were unable to distinguish either ger- 
 minal vesicle or spot. Each ovum was O194 millim. in dia- 
 meter. 
 
 After some days had elapsed, we opened another capsule, and 
 observed, in the greater number of ova, the commencement 
 of a cleavage which appeared to be altogether irregular. In 
 fact, the number of spheres indicated by this cleavage was very 
 variable; and some of the ova, which, we may add, were all 
 provided with a chorion, had assumed an ovoid form (figs. 3, 4, 
 5, 6, 7* 8, 9). The cleavage masses were all dark, and unpro- 
 vided with any nucleus. 
 
 M. Nordmann has been equally unable to observe any nucleus 
 in TergipeSy Rissoa, or Littorina. The clear body which MM. 
 Van Beneden, Nordmann, H. Rathke, F. Miiller, Loven, and 
 other authors, have seen passing from the interior of the vitellus 
 to its surface (to which F. Miiller and Loven attribute the power 
 of determining the cleavage), has not appeared in the ova we are 
 describing, although we have taken great pains to look for it*. 
 
 Some days later we examined many other capsules. The 
 viscous albuminous humour had undergone no appreciable 
 change. However, the ova were not so scattered as before, and 
 had approached one another. Examining them microscopically, 
 we observed that some had undergone no division ; others had 
 remained in a state of incipient division, while around these 
 imperfectly developed ova there were a great number of others 
 in which division was more advanced. We see then, in this 
 case, that the ova have a disposition to collect together, and that 
 although enclosed in the same capsule, they exhibited a great 
 difference in the extent to which the cleavage process had taken 
 
 * In a very recently published Appendix to this Memoir (Supplement til 
 Pectinibranchiernes Udviklings-historie, af J. Koren og D. C. Danielssen), the 
 authors give an account of new observations on this point in Buccinum unda- 
 tum. In examining the youngest ova they have seen the clear (oily) body pass 
 out, and they describe, at length, the mode in which this takes place. 
 
DEVELOPMENT OF THE PECTINIBRANCHIATA. 343 
 
 place. In these ova, 2, 4, 6, 7 > 9, 10, arid even 18, cleavage 
 masses might be counted ; the contents of all were obscure, and 
 without any nucleus, Even at this period, we thought we no- 
 ticed a tendency to agglomerate the ova in the viscous liquid, 
 analogous to that whose effect we observed in Buccinum unda- 
 tum, but it was far from being well marked, and the commencing 
 cleavage threw great obscurity upon what was going on. But all 
 our doubts were completely dissipated on the twelfth day, when 
 the phenomenon which had been exhibited by Buccinum unda- 
 tum was repeated by Purpura lapillus. In fact, the ova were 
 agglomerated and formed a compact mass; the viscous and 
 albuminous liquid had at the same time become as clear as 
 water, and could be separated from the conglomerate with great 
 ease. Examining the latter with attention we observed that it 
 was composed of many groups of various extent and without 
 any determinate form ; these groups, under the microscope, ap- 
 peared to be composed of ova, the greater number of which had 
 undergone cleavage, while others had not (PL XI. fig. 24). 
 
 On the sixteenth day we re-examined many capsules. All the 
 ova were agglomerated, but the conglomerate was a little altered, 
 inasmuch as certain groups had become more distinct, more 
 sharply circumscribed, and projected more from the common 
 mass. Some were cylindrical, others pyriform, but they were 
 all terminated by a peduncle which connected them with the 
 common mass (fig. 27). The microscopical examination of each 
 group showed it to be formed by the union of ova imbedded 
 in a very viscid mass, and invested by a delicate membrane, 
 which soon became covered with very fine cilia (fig. 27). The 
 ova themselves had undergone no further cleavage, and it ap- 
 peared to us that this process had stopped as soon as the agglo- 
 meration commenced. Soon after, we observed a well-marked 
 grayish, semitransparent, finely granular matter, exuding from 
 the sides of the above-mentioned peduncle, and becoming, at a 
 later period, covered with vibratile cilia (the foot) (figs. 26, 27 
 & 28 b}. We also observed a similar mass becoming developed, 
 in the same manner, at the base of the peduncle, and giving 
 origin to two lobes, which afterwards increased and acquired fine 
 cilia at their edges (fig. 7 d). The embryo thus constituted 
 now begins to move a little by the help of its cilia. In fact, it 
 was observed to make feeble efforts in various directions, as if it 
 
344 KOREN AND DANIELSSEN ON THE 
 
 sought to detach itself from the common mass and having, 
 at length, after many fruitless attempts, succeeded in so doing, 
 it immediately began to rotate upon itself. We have, in this 
 manner, observed all the individuals of a conglomerate, be- 
 coming detached and separated, one after the other, and when 
 all the embryos were developed, the mass had totally disappeared. 
 It would seem that in this animal, as in the Buccinum, the 
 number of ova which are grouped together to form the future 
 embryo is altogether variable and fortuitous, for not only is there 
 no discoverable law regulating their union, but these conglome- 
 rates are constituted by very different numbers of ova. Thus 
 we have observed in the same capsule some embryos resulting 
 from the union of three or four ova, while sixty or more, had 
 contributed to form most of the others. The different size of 
 the individuals depended on the same cause. This difference of 
 size was very considerable, for we observed swimming in the 
 liquid contained in the capsule, some embryos of millim. in 
 diameter, and others of as much as 1^ millim. The number of 
 the embryos in a given capsule varied as much as their size ; 
 depending in the same manner on the greater or less number of 
 the ova which had united to form each individual. On the 
 average we found from twenty to forty, rarely more. 
 
 Having now become acquainted with the mode of formation 
 of the embryo in Purpura lapillus, let us turn to another phae- 
 nomenon, one of the most surprising which is to be met with in 
 the development of this mollusk, and which will help to explain 
 the singularity in the development of Buccinum, to which we 
 have already referred. It will be remembered that in the latter 
 animal, many of the ova took no share in the act of conglomera- 
 tion (probably in consequence of accidental obstacles), and that 
 their ova soon died, or rather became developed in an excessively 
 incomplete manner. Something similar occurs in Purpura; 
 and as we have had better opportunities for observing this pecu- 
 liarity in the latter mollusk, we are enabled to give a fuller ac- 
 count of it. We have always found in each capsule an ovum 
 undergoing all stages of cleavage, and which was composed, 
 until the end, of a peripheral layer of clear, and a central mass 
 of dark cells (figs. 10 & 11). A membrane then became rapidly 
 developed around the yelk, and acquired exceedingly fine cilia ; 
 at the upper part of the peripheral layer there were also visible 
 
DEVELOPMENT OF THE PECTINI BRANCHI ATA. 345 
 
 he rudiments of the two rounded lobes (velum) with the foot 
 k figs. 12 a, b, c, 13 & 14 b, c). Cilia quickly made their appear- 
 ance both on the foot and on the lobes : subsequently, scattered 
 cirrhi could be observed upon the lobes, and then the embryo 
 began to rotate. Later still the lobes and the foot increased in 
 size (figs. 15, 16 b, c), and the rudiments of the auditory organs 
 (fig. 16 d) appeared at their base, the membranes of the mantle 
 became more and more thickened, the shell began to be formed 
 on its most sloping part, and calcareous particles to be deposited 
 in it (figs. 14,15,16 a). The embryos whose first development we 
 have just been following were true monsters, and subsequently 
 assumed such various and whimsical forms, that no one could 
 have imagined them to be individuals of the same species. In a 
 few we have seen the salivary gland appear (fig. 16 e\ but it was 
 the only new structure which appeared after the formation of 
 the external organs, and these beings permanently remained in 
 the same state of arrest of development. Finally, until eight 
 weeks had elapsed, this monstrous embryo was always to be met 
 with in the capsule. We have already stated that an ovum of 
 this nature always existed in each capsule, and its embryo was 
 known at once by its small size and the excessive vivacity of its 
 motions. We have sought for them in vain in the capsule after 
 eight weeks, and we suppose that they had all perished. When 
 our attention was first directed to these simple ova, which had 
 regularly undergone the cleavage process, we imagined that their 
 development had taken place in a normal manner; but, far from 
 this, it was, in fact, an abortion. For the viability of the indivi- 
 dual organized, more than one ovum is necessary : and despite 
 the regularity and the vivacity observable in the young product 
 of the single ovum, we see that its development remains in the 
 highest degree incomplete. This single ovum had in fact under- 
 gone all the stages of cleavage, and to all appearance united all 
 the anatomical and physiological conditions necessary to its 
 complete development, while, on the other hand, it appears to 
 us to be incontestable, that it had never been in possession of the 
 materials requisite for the formation of organs. Without doubt 
 there is much that is obscure in these ideas ; we shall endeavour 
 by and by to throw as much light as we can upon them. 
 
 Having described the monstrous embryo resulting from a 
 
346 KOREN AND DANIELSSEN ON THE 
 
 single ovum, we may return to the embryos formed by multiple 
 ova, and describe at length their further development. 
 
 We have already remarked, that after the formation of the 
 ciliary membrane, the foot and the two rounded lobes are the 
 organs first developed. At about the same time we perceive a 
 transparent mass between the membranes and the conglomerate 
 ova (fig. 28 d). Cells are developed in this mass in layers, and 
 give rise to the mantle (figs. 29, 30Z>). The most sloping part of 
 the latter secretes a very clear and viscid humour, which increases 
 by degrees and forms the rudiment of the shell, which, when it 
 first appears, resembles a clear and gelatinous pellicle, wherein 
 subsequently calcareous particles are deposited (fig. 29 a). These 
 particles afterwards increase in number and impede the exami- 
 nation of embryos which are a little older. 
 
 The lobes are small at first, but their volume rapidly increases; 
 a multitude of cilia appear on the surface, cirrhi are developed 
 from their upper edge and produce much more vivacious move- 
 ments (figs. 29 d } 30 e). The foot becomes strongly separated 
 on the ventral surface and thus forms a transverse eminence 
 (fig. 28 b), which rapidly increases in volume and exhibits the 
 first rudiments of the auditory organs at its base, developed as 
 in Buccinum undatum (figs. 29 e, 30/). At the same time as the 
 auditory organs, the rudiments of the tentacles, of the eyes and 
 of the salivary gland, appear. The tentacles commence as two 
 conical eminences, at the base of which the eyes are visible as 
 two rounded vesicles, filled internally with a pellucid liquid \ 
 dark pigment granules may be seen in them (fig. 31 /, m). We 
 have been unable, at this stage of development, to discover any 
 lens, nor have we met with any cilia on the internal parietes of 
 the vesicle. 
 
 The first trace of the salivary glands which manifests itself, 
 is a mass of rounded cells upon each side of the base of the foot, 
 which are usually nucleated. These cells soon acquire a delicate 
 membrane, which afterwards elongates to meet the future oeso- 
 phagus, whose outlines are not yet distinguishable. In pro- 
 portion as the salivary glands are developed, these cells become 
 more and more multiplied in their interior and are closely dis- 
 posed in elongated lines ; we see also, in the widest portion of this 
 organ, a mass of dark yellow pigment granules. In its more 
 
DEVELOPMENT OF THE PECTINIBRANCHI ATA. 347 
 
 delicate part, directed towards the oesophagus, the excretory 
 duct of the gland is indicated, and elongates to meet this por- 
 tion of the intestinal canal (PL XI. figs. 30, 31 g, PL XII. fig. 4). 
 The salivary gland forms but a single conglomerate mass in the 
 adult, but its double excretory duct shows clearly enough, that 
 it was divided into two parts in the very youngest state. 
 
 The heart was seen on the twenty-third day. The mode of 
 its development is analogous to that which occurs in Buccinum. 
 It is situated upon the dorsal side, presents the form of a 
 bladder, and is directed from above downwards and from left to 
 right ; it contracted in this direction, at the rate of forty to fifty 
 pulsations a minute. It possesses primitive muscular fibres, 
 having the form of longitudinal tubes, undivided above. We 
 have met with neither cells nor nuclei in these tubes (PL XII. 
 figs. 1, 3 h). 
 
 In this stage of development, the branchial cavity is not deep 
 enough to contain the whole of the heart, a considerable portion 
 of which extends beyond the edge of the mantle. Subsequently, 
 when the mantle elongates and covers in the back of the animal, 
 its edge is directed more outwards and detaches itself from the 
 body, so that the branchial cavity becomes deeper and wider 
 and encloses the heart completely. 
 
 We have as yet been unable to observe the circulatory current 
 in this mollusk. 
 
 It is only after the formation of these organs that the buccal 
 aperture, the proboscis and the oesophagus, are perceptible. 
 The proboscis is exceedingly short and its parietes are very 
 thick, so that it is easily seen through the oesophagus (fig. 3H). 
 The latter is cylindrical and takes a course beneath the stomach 
 (figs. 31, 32 k). The latter lies to the left, it is small and oval, 
 and a long and delicate intestine passes out of it, which turns 
 to the right, bends back afterwards to the opposite side in a 
 curved direction, and finally terminates in the branchial cavity 
 by a projecting anus (fig. 32 /, m, n). 
 
 The oesophagus, the stomach and the intestine are ciliated 
 upon their inner surface. 
 
 It is not until a somewhat later stage of development that the 
 nervous system is distinctly discoverable. It is composed of 
 two cerebroid ganglia upon each side of the oesophagus (figs. 31 n, 
 
348 KOREN AND DANIELSSEN ON THE 
 
 32 q) ; these ganglia are united by means of a commissure, and 
 give rise to two other commissures (fig. 31 n, s), which connect 
 them with the pedal ganglia. They are oval, are distinguished 
 by their clear yellow colour, and send a great number of 
 branches to the foot (fig. 32 s). 
 
 We have been unable to trace the nervous system further, all 
 parts of the body having rapidly become opake. It is also 
 about the time of the appearance of the nervous system, that 
 the first traces of the branchiae, of the siphon and of the retractor 
 muscles of the foot, are discoverable. The branchiae spring 
 from the edge of the mantle and then form a hollow cylinder, 
 which is twisted into loops ; fine cilia appear upon its inner 
 edge. Subsequently it becomes a little flattened and consider- 
 ably spread out. In its parietes, longitudinal and transverse 
 fibres are discoverable, which we regard as muscular tubules. 
 The cilia which exist in the middle of each loop have an extra- 
 ordinary length (PI. XII. fig. 8 b, c). 
 
 After the development of the branchiae, it becomes exceed- 
 ingly difficult to make out the formation of the other organs ; 
 on the one hand, because the animal rarely protrudes from the 
 shell sufficiently to show these parts, and on the other, because 
 the mantle is greatly thickened and a large quantity of calca- 
 reous matter has been deposited in the shell. The latter has 
 taken the shape of that of a Nautilus, and when it is placed 
 under a strong magnifying power, it is observable that the cal- 
 careous matter is deposited in the form of a network with fine 
 meshes (fig. 2). The two rounded lobes diminish in volume 
 (fig. 5). The foot, lobed above, takes on more and more the 
 shape of that of the adult animal, and the operculum which 
 closes the aperture of the shell is completely developed (fig. 6). 
 The heart is, in this stage, divided into two chambers, whence 
 the great vessels arise. The lenses of the eyes are clearly di- 
 stinguishable, and we have frequently met with a single eye 
 presenting two streaks of pigment, but never with more than 
 one lens. The branchial cavity, whose internal surface is 
 covered with cilia, has become, at this period of development, 
 deep enough to enclose the heart completely. The edge of the 
 mantle, which divaricates further and further from the body of 
 the animal, is ciliated, and at the bottom of the branchial cavity 
 
DEVELOPMENT OF THE PECT1NIBRANCHIATA. 349 
 
 we observe, for the first time, a contractile vesicle similar to that 
 which exists in Buccinum undatum. 
 
 After the lapse of eight weeks the young had not yet left the 
 capsule, but when one was taken out, it began to creep like the 
 adult animal, with foot, tentacles and siphon stretched out. 
 It is then distinguished from the adult by the incomplete dis- 
 appearance of the lobes, by the shell being still soft, and by the 
 spire having only one or two turns (fig. 6). From the ninth 
 and tenth weeks the young begin to leave the capsules, the 
 rounded lobes disappear, and behind the tentacles an elevated 
 line may be seen occupying their previous place (fig. 7) ; the 
 shell has elongated and approximates more nearly that of the 
 adult; it is hard, frangible, and almost opake; the last turn of 
 the spire, however, is not yet formed. 
 
 We shall not describe the development of the organs of 
 Purpura at greater length, because it does not differ from what 
 we see in Buccinum undatum. 
 
 We may call the attention of the reader to the interesting 
 investigations of Kolliker and Siebold* on Actinophrys Sol and 
 on Diplozoon paradoxum; for, perhaps, something approxima- 
 ting to what we have just described may be found in their ob- 
 servations. 
 
 In conclusion, we may add, that we entertain a strong desire 
 to have the opportunity of continuing our investigations upon 
 other genera allied to Buccinum and Purpura, for assuredly, 
 with some slight modifications, all these Mollusks are developed 
 in the same \vay. 
 
 Summary. 
 
 For the more ready comprehension of the history of the de- 
 velopment of Buccinum undatum and of Purpura lapillus, we 
 here shortly sketch the most essential points. 
 
 Buccinum undatum. 
 
 1 . The ovigerous capsule is filled with a transparent, colour- 
 less viscous liquid which resembles white of egg. Each capsule 
 encloses a mass of ova (of 6-8 centimetres). 
 
 * Z I'it schr'ift fiir wiss. Zoologie, torn. i. p. 198, and torn. iii. p. 62. 
 
350 KOREN AND DANIELSSEN ON THE 
 
 2. Each ovum consists of a chorion and albumen, of a vitel- 
 lary membrane, and of a vitellus composed of larger or smaller 
 globules. Its diameter varies from 0'25 7-0*264 millim. In 
 the egg, when laid, we have never been able to observe either 
 germinal vesicle or spot. 
 
 3. The cleavage which occurs in other mollusks does not 
 take place in these animals. 
 
 4. The ova begin to approximate towards the eighteenth day, 
 and the chorion is detached. The yelk, more or less laid bare, 
 invested only by its very firm membrane, is enveloped by the 
 viscous albumen-like liquid. 
 
 5. Some days later, the ova, even those which were most 
 distant, approximate and form only a single mass, whose dif- 
 ferent portions, larger or smaller, have become grouped ; so that 
 each group, usually composed of from six to sixteen ova, is 
 distinguishable by the naked eye. 
 
 6. On the twenty-third day, these groups are still more 
 distinctly marked out, and are invested by a very delicate mem- 
 brane peculiar to each group, which has by this time taken on 
 an oval or reniform shape : the ova are connected together, and 
 the liquid which enclosed them has lost its viscosity. 
 
 7. Towards the twenty-fifth day the groups possess a more 
 decided membrane and boundaries. Many of the ova which 
 have remained isolated and simple appear as embryos, whilst 
 the others are attached together. 
 
 8. The embryo thus formed consists of a delicate membrane 
 enclosing many ova. 
 
 9. The number of the ova grouped to form one embryo varies 
 greatly, amounting in some cases to as many as a hundred and 
 more. 
 
 10. The number of embryos in different capsules varies ; 
 commonly it is from six to sixteen. 
 
 11. The first organs which are formed after the membrane in 
 question are the rounded lobes with cilia and cirrhi. [The em- 
 bryo then begins to move.] At a later period, the foot, the 
 mantle, the shell, the auditory organs, the proboscis, the eyes, 
 the salivary gland, the heart, and the contractile bladder appear; 
 still later, the digestive and the nervous systems and the 
 branchiae, are developed. 
 
DEVELOPMENT OF THE PECTINIBRANCH1ATA. 351 
 
 12. After an interval of at least eight weeks, we see the 
 young leave their capsule ; the shell is a little more elongated 
 (about 2 millim. long), hard, frangible and semitransparent. 
 The lobes have disappeared, and the young animal creeps like 
 the adult ; it is still distinguishable by the number of the turns 
 of its spire (there are only one or two). We should observe, 
 that we have hitherto found no traces of the generative organs 
 in these young. 
 
 13. Finally, the grouped ova are sufficiently numerous to fill 
 the posterior part of the shell. 
 
 Purpura lapillus. 
 
 1. The ova, dispersed through an extraordinarily thick and 
 viscous humour, fill the ovigerous capsules of the animal, which 
 are flask-shaped. 
 
 2. The size of the ovum is about 0*194 millim. This ovum 
 is composed of a delicate chorion, of an albumen, of a vitelline 
 membrane and yelk. 
 
 3. The vitellus undergoes a very irregular cleavage. The 
 cleavage masses have no nuclei. 
 
 4. After a certain progress of the cleavage, the ova begin to 
 be grouped together. 
 
 5. On the twelfth and thirteenth days the ova have become, 
 so to say, a compact mass, subdivided into many masses of ova, 
 disposed in bunches. 
 
 6. On the sixteenth day the separate groups were more 
 sharply circumscribed, and projected from the remainder of the 
 mass. These projecting groups soon took a cylindrical or pyri- 
 form shape, and were fixed to the rest by means of a peduncle. 
 The microscope showed them to be composed of a delicate 
 ciliated membrane, and that they enclosed a mass of ova; a 
 transparent substance exuded from the two sides of the peduncle, 
 upon which fine cilia appeared (the foot) ; and at the base of 
 this same peduncle the first traces of the lobes were distinguish- 
 able. Finally, many of these pyriform bodies became detached 
 from the mass and rotated upon themselves ; these were the 
 embryos. 
 
 7. It is impossible to determine the exact number of the ova 
 which go to form one embryo, as it varies greatly. In each capsule 
 
352 KOREN AND DAXIELSSEN ON THE 
 
 an embryo proceeding from a single ovum is constantly met with; 
 but this embryo never attains to a complete development. 
 
 8. The number and size of the embryos vary in different cap- 
 sules; the average number is from 20-40. The largest embryo 
 was 1^ millim. in diameter. 
 
 9. The first organs which are formed after the tegumentary 
 membrane are the foot with its vibratile cilia and the two 
 rounded lobes, which are both ciliated and provided with cirrhi ; 
 then the mantle, the shell and the auditory organs, the salivary 
 glands, the heart (on the twenty-third day), the eyes and the 
 tentacles. The digestive apparatus, the nervous system, the 
 branchiae, the siphon, and the retractor muscles of the foot, ap- 
 peared later still. Subsequently the heart divides into two 
 chambers, the shell presents one or two spiral turns, and it is 
 only after all these changes that the contractile bladder appears. 
 
 After eight weeks the young had not yet left the capsules ; 
 and when one was extracted in this stage of development, it 
 began to creep like the adult animal, from which however it 
 was distinguished by the lobes, which had not wholly disap- 
 peared, and by the shell, which still had only one or two spiral 
 turns. 
 
 10. Towards the ninth or tenth week, the young leaves the 
 capsule ; the lobes have disappeared ; the shell has become fra- 
 gile and opake. 
 
 EXPLANATION OF THE PLATES. 
 Buccinum undatum. Plate X. 
 
 Fig. 1. An egg from the oviduct of Buccinum, X 200. a, yelk; b, germinal 
 vesicle ; c, germinal spot. 
 
 Fig. 2. Egg from a capsule, X 200. a, chorion ; b, vitellary membrane ; 
 c, yelk. 
 
 Figs. 3 & 4. Embryos, a, chorion ; 6, yelk with its membrane ; c, rudi- 
 ments of the two lobes. 
 
 Fig. 5. Embryo seen from the side, a, membranous shell ; 6, mantle ; 
 c, yelk ; d, lobes ; e, foot. 
 
 Fig. 6. Embryo. Dorsal view, e, heart. 
 
 Fig. 7. Embryo. Ventral view. /, foot. 
 
 Fig. 8. Embryo. Dorsal view, k, salivary glands. 
 
 Fig. 9. Embryo. Ventral view, i, tentacles j /r, proboscis ; I, oesoplmgus ; 
 m, stomach. 
 
DEVELOPMENT OF THE PECTIN1BBANCHI ATA. 353 
 
 Fig. 10. Embryo from the side, a-g, as in the foregoing figures; h, eyes; 
 i, tentacles ; k, proboscis. 
 
 Fig. 11. Young Buccinum seen laterally, a, shell; b, mantle; d, lobes; 
 e, heart ; /, foot ; g, auditory organ ; h, operculum ; i, head ; k, eyes; 
 I, tentacles ; m, mouth ; n, stomach ; o, intestine ; p, branchiae ; 
 q, bladder ; r y liver ; s, muscles ; t, cerebral ganglia ; u, commissures ; 
 v, pedal ganglia ; x, commissure ; y, ganglia of the pedal lobes. 
 
 Fig. 12. Young seen laterally. The same letters as in the foregoing figures, 
 except o, salivary glands ; p, cerebral ganglia ; q, commissure ; 
 r, pedal ganglia, with their nerves ; s, ganglia of the pedal lobe ; 
 t, commissure ; u, siphon ; v, branchiae. 
 
 Fig. 13. Dorsal view of young, a, shell; b, mantle; c, foot; d, head; 
 e, eyes; /, tentacles; y, siphon. 
 
 Fig. 14. Nervous system of a young individual seen laterally and compressed. 
 a, head ; b, eyes ; c, tentacles ; d, foot ; e, oesophagus ; /, cerebral 
 ganglia ; g, optic nerve ; h, auditory nerve ; i, commissure ; k, pedal 
 ganglia ; I, nerves of the foot ; m, commissure ; n, ganglion of the 
 pedal lobes ; o, its nervous branches ; p, intestinal nerve. 
 
 Fig. 15. One of the lobes, X 400. a, primitive longitudinal tubes; b, trans- 
 verse simple tubes ; c, calcareous granules ; d, cilia ; e, cirrhi. 
 
 Fig. 16. Eyes of an embryo, X 400. a, capsules whose external and internal 
 surfaces are ciliated ; b, membrane enclosing pigment granules. 
 
 Purpura lapillus. Plate XI. 
 
 Fig. 1. Ovigerous capsule, containing ova in different states and of the natural 
 
 size. 
 
 Fig. 2. An egg magnified, a, chorion ; b, vitelline membrane; c, yelk. 
 Figs. 3, 4, 5, 6, 7, 8. Ova, in various stages of cleavage, magnified. 
 Fig. 9. Embryo magnified, a, ciliated membrane ; b } cells. 
 Fig. 10. Embryo many days older, a, ciliated membrane ; b, peripheral cells ; 
 
 c, central cells. 
 Fig. 106. The same, X 350. 
 
 Fig. 1 1 . An embryo at nearly the same stage of development. 
 
 Fig. 12. A rather more advanced embryo, viewed laterally, a, membrane; 
 
 6, the two lobes ; c, the rudimentary foot. 
 
 Fig. 13. An embryo, viewed laterally, X 350. o, shell; b, lobes; c, foot. 
 Fig. 14. An embryo, viewed laterally, X 350. a, shell; b, lobe; c, foot; 
 
 d y mantle. 
 Fig. 15. An embryo, viewed dorsally, X 380. a, shell; 6, lobes ; c, foot ; 
 
 d, mantle. 
 
 Fig. 16. An embryo, x 350. a, shell, in which calcareous granules are depo- 
 sited ; &, lobes ; c, foot ; d, auditory organ ; e, rudiments of the sali- 
 vary gland ; /, mantle. 
 
 Figs. 17, 18, 19, 20, 21, 22, 23. Ova in different stages of development. 
 
 Fig. 24. Grouped ova. 
 
 Fig. 25. Ovum, slightly magnified, and taken out of the capsule to show the 
 result of the grouping, a, grouped ova, which have not yet taken a 
 decided form ; b, embryo in the earliest state. 
 SCIEN. MEM. Nat. Hist. VOL. I. PART IV. 23 
 
354 ON THE DEVELOPMENT OF THE PECTINIBRANCHIATA. 
 
 Fig. 26. An embryo, strongly attached to the mass, x 100. a, membrane; 
 
 b, foot; c, ova, grouped in various stages. 
 
 Fig. 27. Embryo, x 100. a, membrane, ciliated here and there; b, foot; 
 
 c, peduncle ; d, rudimentary lobe ; e, grouped ova. 
 
 Fig. 28. Embryo, X 100. a, membrane ; b, foot ; c, lobe ; c?, exuded mass; 
 
 e, grouped ova. 
 Fig. 29. Embryo, X 100. o, shell ; b, mantle ; c, foot ; d, lobe ; e, auditory 
 
 organ ; /, grouped ova. 
 Fig. 30. Embryo, viewed laterally, x 100. a, shell; 6, mantle; c, grouped 
 
 ova; d, foot ; e, lobe ; /, auditory organ ; g, salivary gland ; h, heart ; 
 
 z, rudimentary stomach. 
 Fig. 31. Embryo, viewed laterally, x 100. a, b, c, d, e,f, g, h, as in fig. 30; 
 
 i, proboscis ; k, oasophagus ; /, tentacle ; m, eyes ; n, cerebroid ganglia. 
 Fig. 32. Embryo, viewed laterally, X 100. Letters as before, except /, sto- 
 mach ; m, intestine ; n, anus ; o, tentacles ; p, eyes ; q, cerebroid 
 
 ganglia ; r, commissure ; s, pedal ganglia. 
 
 Plate XII. 
 
 Fig. 1. Heart, x about 450. a, auricle; b, ventricle; c, primitive muscular 
 
 tubes; d, large vessel. 
 Fig. 2. Calcareous network, x about 450. 
 Fig. 3. Embryo at the twenty-third day. 
 Fig. 4. Salivary gland. 
 Figs. 5, 6, 7, 9. Embryos further advanced. 
 Fig. 8. Developing branchia. 
 
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