UC-NRLF 
 
 B 3 272 D33 
 
v 
 
 SIRKfcLEY \ 
 
 LIBRARY 
 
 UNIVERSITY OF 
 CALIFORNIA / 
 
 akwctence A Na*jr 
 
STUDIES 
 
 ANIMAL LIFE 
 
 GEORGE HENRY LEWES, 
 
 AUTHOR OF "LIFE OF GOETHE," "THE PHYSIOLOGY OF COMMON LIFE,' 
 <fcc., &c. 
 
 UNI VIES ITT 
 
 NEW YORK: 
 HARPER & BROTHERS, PUBLISHERS, 
 
 FBANKLIN 8 Q U A B E. 
 1860. 
 
81OLOGY 
 UBRARY 
 
 G 
 
CONTENTS. 
 
 CHAPTER I. 
 
 Omnipresence of Life. The Microscope. An Opalina and its 
 Wonders. The Uses of Cilia. How our Lungs are protected 
 from Dust and Filings. Feeding without a Mouth or Stomach. 
 What is an Organ? How a complex Organism arises. 
 Early Stages of a Frog and a Philosopher. How the Plants 
 feed. Parasites of the Frog. Metamorphoses and Migrations 
 of Parasites. Life within Life. The budding of Animals. 
 A steady Bore. Philosophy of the infinitely little Page 9 
 
 CHAPTER H. . 
 
 Ponds and Rock-pools. Our necessary Tackle. Wimbledon 
 Common. Early Memories. Gnat Larvae. Entomostraca 
 and their Paradoxes. Races of Animals dispensing with the 
 sterner Sex. Insignificance of Males. Volvox Globator: is it 
 an Animal? Plants swimming like Animals. Animal Retro- 
 gressions. The Dytiscus and its Larva. The Dragon-fly Lar- 
 va. Mollusks and their Eggs. Polypes, and how to find them. 
 A new Polype, Hydra rubra. Nest-building Fish. Con- 
 tempt replaced by Reverence 39 
 
 CHAPTER m. 
 
 A garden Wall, and its Traces of past Life. Not a Breath per- 
 ishes. A Bit of dry Moss and its Inhabitants. The "Wheel- 
 bearers." Resuscitation of Rotifers: drowned into Life. 
 Current Belief that Animals can be revived after complete De- 
 siccation. Experiments contradicting the Belief. Spallanzani's 
 Testimony. Value of Biology as a Means of Culture. Classi- 
 fication of Animals: the five great Types. Criticism of Cu- 
 vier's Arrangement 59 
 
Vlll CONTENTS. 
 
 CHAPTER IV. 
 
 An extinct Animal recognized by its Tooth : how came this to be 
 possible ? The Task of Classification. Artificial and natural 
 Methods. Linnaeus, and his Baptism of the Animal Kingdom : 
 his Scheme of Classification. What is there underlying all 
 true Classification ? The chief Groups. What is a Species ? 
 Eestatement of the Question respecting the Fixity or Variability 
 of Species. The two Hypotheses. Illustration drawn from the 
 Romance Languages. Caution to Disputants Page 86 
 
 CHAPTER V. 
 
 Talking in Beetles. Identity of Egyptian Animals with those now 
 existing : Does this prove Fixity of Species ? Examination of 
 the celebrated Argument of Species not having altered in four 
 thousand Years. Impossibility of distinguishing Species from 
 Varieties. The Affinities of Animals. New Facts proving the 
 Fertility of Hybrids. The Hare and the Rabbit contrasted. 
 Doubts respecting the Development Hypothesis. On Hypoth- 
 esis in Natural History. Pliny, and his Notion on the Forma- 
 tion of Pearls. Are Pearls owing to a Disease of the Oyster? 
 Formation of the Shell; Origin of Pearls. How the Chinese 
 manufacture Pearls 107 
 
 CHAPTER VI. 
 
 Every Organism a Colony. What is a Paradox ? An Organ is 
 an independent Individual and a dependent one. A Branch 
 of Coral. A Colony of Polypes. The Siphonophora. Uni- 
 versal Dependence. Youthful Aspirings. Our Interest in the 
 Youth of great Men. Genius and Labor. Cuvier's College 
 Life ; his Appearance in Youth ; his Arrival in Paris. Cuvier 
 and Geoffrey St.Hilaire. Causes of Cuvier's Success. One of 
 his early Ambitions. M. le Baron. Omnia vincit labor. Con- 
 clusion 128 
 
STUDIES IN ANIMAL LIFE 
 
 CHAPTER I. 
 
 Omnipresence of Life. The Microscope. An Opalina and its 
 Wonders. The Uses of Cilia. How our Lungs are protected 
 from Dust and Filings. Feeding without a Mouth or Stomach. 
 What is an Organ? How a complex Organism arises. 
 Early Stages of a Frog and a Philosopher. How the Plants 
 feed. Parasites of the Frog. Metamorphoses and Migrations 
 of Parasites. Life within Life. The budding of Animals. 
 A steady Bore. Philosophy of the infinitely little. 
 
 COME with me, and lovingly study Nature, as she 
 breathes, palpitates, and works under myriad forms 
 of Life forms unseen, unsuspected, or unheeded 
 by the mass of ordinary men. Our course may be 
 through park and meadow, garden and lane, over 
 the swelling hills and spacious heaths, beside the 
 running and sequestered streams, along the tawny 
 coast, out on the dark and dangerous reefs, or under 
 dripping caves and slippery ledges. It matters lit- 
 tle where we go: every where in the air above, 
 the earth beneath, and waters under the earth we 
 are surrounded with Life. Avert your eyes a while 
 from our human world, with its ceaseless anxieties, 
 its noble sorrow, poignant, yet sublime, of conscious 
 imperfection aspiring to higher states, and contem- 
 A2 
 
10 STUDIES IN ANIMAL LIFE. 
 
 plate the calmer activities of that other world with 
 which we are so mysteriously related. I hear you 
 exclaim, 
 
 "The proper study of mankind is man ;" 
 
 nor will I pretend, as some enthusiastic students 
 seem to think, that 
 
 "The proper study of mankind is cells;" 
 
 but agreeing with you, that man is the noblest 
 study, I would suggest that under the noblest there 
 are other problems which we must not neglect. 
 Man himself is imperfectly known, because the laws 
 of universal Life are imperfectly known. His life 
 forms but one grand illustration of Biology the 
 science of Life,* as he forms but the apex of the 
 animal world. 
 
 Our studies here will.be of Life, and chiefly of 
 those minuter or obscurer forms, which seldom at- 
 tract attention. In the air we breathe, in the water 
 we drink, in the earth we tread on, Life is every 
 where. Nature lives: every pore is bursting with 
 Life ; every death is only a new birth, every grave 
 a cradle. And of this we know so little, think so 
 little ! Around us, above us, beneath us, that great 
 mystic drama of creation is being enacted, and we 
 will not even consent to be spectators! Unless 
 animals are obviously useful or obviously hurtful 
 
 * The needful term Biology (from Bios, life, and logos, dis- 
 course) is now becoming generally adopted in England, as in Ger- 
 many. It embraces all the separate sciences of Botany, Zoology, 
 Comparative Anatomy, and Physiology. 
 
STUDIES IN ANIMAL LIFE. 11 
 
 to us, we disregard them. Yet they are not alien, 
 but akin. The Life that stirs within us stirs with- 
 in them. We are all "parts of one transcendent 
 whole." The scales fall from our eyes when we 
 think of this ; it is as if a new sense had been vouch- 
 safed to us, and we learn to look at Nature with a 
 more intimate and personal love. 
 
 Life every where ! The air is crowded with birds 
 ~ beautiful, tender, intelligent birds to whom life 
 is a song and a thrilling anxiety, the anxiety of 
 love. The air is swarming with insects those lit- 
 tle animated miracles. The waters are peopled 
 with innumerable forms, from the animalcule, so 
 small that one hundred and fifty millions of them 
 would not weigh a grain, to the whale, so large 
 that it seems an island as it sleeps upon the waves. 
 The bed of the seas is alive with polypes, crabs, 
 star-fishes, and with sand-numerous shell-animal- 
 cules. The rugged face of rocks is scarred by the 
 silent boring of soft creatures, and blackened with 
 countless mussels, barnacles, and limpets. 
 
 Life every where ! on the earth, in the earth, 
 crawling, creeping, burrowing, boring, leaping, run- 
 ning. If the sequestered coolness of the wood tempt 
 us to saunter into its checkered shade, we are sa- 
 luted by the murmurous din of insects, the twitter 
 of birds, the scrambling of squirrels, the startled 
 rush of unseen beasts, all telling how populous is 
 this seeming solitude. If we pause before a tree, 
 or shrub, or plant, our cursory and half-abstracted 
 
12 STUDIES IN ANIMAL LIFE. 
 
 glance detects a colony of various inhabitants. We 
 pluck a flower, and in its bosom we see many a 
 charming insect busy at its appointed labor. We 
 pick up a fallen leaf, and if nothing is visible on it, 
 there is probably the trace of an insect larva hidden 
 in its tissue, and awaiting there development. The 
 drop of dew upon this leaf will probably contain 
 its animals, visible under the microscope. This 
 same microscope reveals that the Hood-rain sudden- 
 ly appearing on bread, and awakening superstitious 
 terrors, is nothing but a collection of minute ani- 
 mals (Monas prodigiosa) ; and that the vast tracts 
 of snow which are reddened in a single night owe 
 their color to the marvelous rapidity in reproduc- 
 tion of a minute plant (Protococcus nivalis). The 
 very mould which covers our cheese, our bread, our 
 jam, or our ink, and disfigures our damp walls, is 
 nothing but a collection of plants. The many-col- 
 ored fire which sparkles on the surface of a summer 
 sea at night, as the vessel plows her way, or which 
 drips from the oars in lines of jeweled light, is pro- 
 duced by millions of minute animals. 
 
 Nor does the vast procession end here. Our very 
 mother-earth is formed of the debris of life. Plants 
 and animals which have been build up its solid 
 fabric.* We dig downward thousands of feet be- 
 low the surface, and discover with surprise the 
 
 * See EHRENBERG: Microgeologie : das Erden und Felsen 
 schaffende Wirken des unsichtbar kleinen selbststandigen Lebcns auf 
 der Erde. 1854. 
 
STUDIES IN ANIMAL LIFE. 13 
 
 skeletons of strange, uncouth animals, which roamed 
 the fens and struggled through the woods before 
 man was. Our surprise is heightened when we 
 learn that the very quarry itself is mainly com- 
 posed of the skeletons of microscopic animals ; the 
 flints which grate beneath our carriage wheels are 
 but the remains of countless skeletons. The Apen- 
 nines and Cordilleras, the chalk cliffs so dear to 
 homeward-nearing eyes these are the pyramids of 
 by-gone generations of atomies. Ages ago these 
 tiny architects secreted the tiny shells which were 
 their palaces ; from the ruins of these palaces we 
 build our Parthenons, our St. Peters, and our Lou- 
 vres. So revolves the luminous orb of Life ! Gen- 
 erations follow generations; and the Present be- 
 comes the matrix of the Future, as the Past was of 
 the Present the Life of one epoch forming the pre- 
 lude to a higher Life. 
 
 "When we have thus ranged air, earth, and water, 
 rinding every where a prodigality of living forms, 
 visible and invisible, it might seem as if the survey 
 were complete. And yet it is not so. Life cradles 
 within Life. The bodies of animals are little worlds, 
 having their own animals and plants. A celebrated 
 Frenchman has published a thick octavo volume 
 devoted to the classification and description of "The 
 Plants which grow on Men and Animals;"* and 
 many Germans have described the immense variety 
 
 * CHARLES EOBIN : Histoire Naturelle des Vegetaux Parasites 
 qui croissent sur VHomme et sur les Animaux Vivants. 1853. 
 
 A* 
 
14 STUDIES IN ANIMAL LIFE. 
 
 of animals which grow on and in men and animals ; 
 so that science can now boast of a parasitic Flora 
 and Fauna. In the fluids and tissues, in the eye, 
 in the liver, in the stomach, in the brain, in the 
 muscles, parasites are found, and these parasites 
 have often their parasites living in them ! 
 
 We have thus taken a bird's-eye view of the field 
 in which we may labor. It is truly inexhaustible. 
 We may begin where we please, we shall never 
 come to an end ; our curiosity will never slacken. 
 
 " And whosoe'er in youth 
 Has through ambition of his soul given way 
 To such desires, and grasp'd at such delights, 
 Shall feel congenial stirrings late and long." 
 
 As a beginning, get a microscope. If you can not 
 borrow, boldly buy one. Few purchases will yield 
 you so much pleasure ; and, while you are about it, 
 do, if possible, get a good one. Spend as little 
 money as you can on accessory apparatus and ex- 
 pensive fittings, but get a good stand and good 
 glasses. Having got your instrument, bear in mind 
 these two important trifles work by daylight, sel- 
 dom or never by lamplight ; and keep the unoccu- 
 pied eye open. With these precautions you may 
 work daily for hours without serious fatigue to the 
 eye. 
 
 Now where shall we begin? Any where will 
 do. This dead frog, for example, that has already 
 been made the subject of experiments, and is now 
 awaiting the removal of its spinal cord, will serve 
 
STUDIES IN ANIMAL LIFE. 
 
 15 
 
 us as a text from which profitable lessons may be 
 drawn. We snip out a portion of its digestive tube, 
 which, from its emptiness, seems to promise little ; 
 but a drop of the liquid we find in it is placed on 
 a glass slide, covered with a small piece of very- 
 thin glass, and brought under the microscope. Now 
 look. There are several things which might occu- 
 py your attention, but dis- 
 regard them now to watch 
 that animalcule which you 
 observe swimming about. 
 What is it ? It is one of the 
 largest of the Infusoria, and 
 is named Opalina. When 
 I call this an Infusorium I 
 am using the language of 
 text-books ; but there seems 
 to be a growing belief among 
 zoologists that the Opalina 
 
 ig no t an Infusorium, but the 
 . . 
 
 infantile condition of some 
 worm -(Distoma T). However, it will not grow into 
 a mature worm as long as it inhabits the frog; 
 it waits till some pike or bird has devoured the 
 frog, and then, in the stomach of its new captor, it 
 will develop into its mature form then, and not 
 till then. This surprises you. And well it may; 
 but thereby hangs a tale, which to unfold for the 
 present, however, it must be postponed, because the 
 Opalina itself needs all our notice. 
 
 Fig. I.-OPALINA EAXAKTTM. 
 A, front view; R, side view mag- 
 
16 STUDIES IN ANIMAL LIFE. 
 
 Obser.e how transparent it is, and with what 
 easy, undulating grace it swims about; yet this 
 swimmer has no arms, no legs, no tail, no backbone 
 to serve as a fulcrum to moving muscles nay, it has 
 no muscles to move with. 'Tis a creature of the 
 most absolute abnegations sans eyes, sans teeth, 
 sans every thing ; no, not sans every thing, for, as 
 we look attentively, we see certain currents pro- 
 duced in the liquid, and, on applying a higher mag- 
 nifying power, we detect how these currents are 
 produced. All over the surface of the Opalina 
 there are delicate hairs in incessant vibration ; these 
 are the cilia* They lash the water, and the animal 
 is propelled by their strokes, as a galley by its hund- 
 red oars. This is your first sight of that ciliary ac- 
 tion of which you have so often read, and which 
 you will henceforth find performing some important 
 service in almost every animal you examine. Some- 
 times the cilia act as instruments of locomotion; 
 sometimes as instruments of respiration, by contin- 
 ually renewing the current of water ; sometimes as 
 the means of drawing in food, for which purpose 
 they surround the mouth, and by their incessant 
 action produce a small whirlpool into which the 
 food is sucked. An example of this is seen in the 
 Yorticella. (Fig. 2.) 
 
 Having studied the action of these cilia in micro- 
 scopic animals, you will be prepared to understand 
 their office in your own organism. The lining 
 
 * From ciliwn, a hair. 
 
STUDIES IN ANIMAL LIFE. 
 Fig. 2. 
 
 17 
 
 GEOTIP OP VOBTICELLA NEBUIJFEKA on a Stem of Weed, magnified. 
 
 A, one undergoing spontaneous division ; B, another spirally retracted on its 
 stalk ; C, one with cilia refracted ; D, a bud detached and swimming free. 
 
 membrane of your air-passages is covered with cilia, 
 which may be observed by following the directions 
 of Professor Sharpey, to whom science is indebted 
 for a very exhaustive description of these organs. 
 " To see them in motion, a portion of the ciliated 
 mucous membrane may be taken from a recently- 
 killed quadruped. The piece of membrane is to be 
 folded with its free, or ciliated surface outward, 
 placed on a slip of glass, with a little water or serum 
 of blood, and covered with thin glass or mica. 
 When it is now viewed with a power of 200 diam- 
 
18 STUDIES IN ANIMAL LIFE. 
 
 eters or upward, a very obvious agitation will be 
 perceived on the edge of the fold, and this appear- 
 ance is caused by the moving cilia with which the 
 surface of the membrane is covered. Being set 
 close together, and moving simultaneously or in 
 quick succession, the cilia, when in brisk action, 
 give rise to the appearance of a bright transparent 
 fringe along the fold of the membrane, agitated by 
 such a rapid and incessant motion that the single 
 threads which compose it can not be perceived. 
 The motion here meant is that of the cilia them- 
 selves; but they also set in motion the adjoining 
 fluid, driving it along the ciliated surface, as is in- 
 dicated by the agitation of any little particles that 
 may accidentally float in it. The fact of the con- 
 veyance of fluids and other matters along the cili- 
 ated surface, as well as the direction in which they 
 are impelled, may also be made manifest by im- 
 mersing the membrane in fluid, and dropping on it 
 some finely -pulverized substance (such as charcoal 
 in fine powder), which will be slowly but steadily 
 carried along in a constant and determinate direc- 
 tion."* 
 
 It is an interesting fact, that while the direction 
 in which the cilia propel fluids and particles is gen- 
 erally toward the interior of the organism, it is 
 sometimes reversed, and, instead of beating the par- 
 
 * Quoin's Anatomy. By SHAEPEY and ELLIS. Sixth edition. 
 I., p. Ixxiii. See also SHARPEY'S article Cilia, in the Cyclopaedia 
 of Anatomy and Physiology. 
 
STUDIES IN ANIMAL LIFE. 19 
 
 tides inward, the cilia energetically beat them back 
 if they attempt to enter. Fatal results would ensue 
 if this were not so. Our air-passages would no 
 longer protect the lungs from particles of sand, coal- 
 dust, and filings flying about the atmosphere ; on 
 the contrary, the lashing hairs which cover the sur- 
 face of these passages would catch up every parti- 
 cle,, and drive it onward into the lungs. Fortunate- 
 ly for us, the direction of the cilia is reversed, and 
 they act as vigilant janitors, driving back all va- 
 grant particles with a stern " No admittance, even 
 on business !" In vain does the whirlwind dash a 
 column of dust in our faces in vain does the air, 
 darkened with coal-dust, impetuously rush up the 
 nostrils ; the air is allowed to pass on, but the dust 
 is inexorably driven back. Were it not so, how 
 could miners, millers, iron- workers, and all the mod- 
 ern Tubal Cains contrive to live in their loaded 
 atmospheres? In a week their lungs would be 
 choked up. 
 
 Perhaps you will tell me that this is the case 
 that manufacturers of iron and steel are very subject 
 to consumption, and that there is a peculiar discol- 
 oration of the lungs which has often been observed 
 in coal-miners examined after death. 
 
 Not being a physican, and not intending to trouble 
 you with medical questions, I must still place be- 
 fore you three considerations, which will show how 
 untenable this notion is. First, although consump- 
 tion may be frequent among the Sheffield workmen. 
 
20 STUDIES IN ANIMAL LIFE. 
 
 the cause is not to be sought in their breathing 
 filings, but in the sedentary and unwholesome con- 
 finement incidental to their occupation. Miners 
 and coal-heavers are not troubled with ,consump- 
 tion. Moreover, if the filings were the cause, all 
 the artisans would suffer, when all breathe the same 
 atmosphere. Secondly, while it is true that dis- 
 colored lungs have been observed in some miners, 
 it has not been observed in all or in many ; where- 
 as it has been observed in men not miners, not ex- 
 posed to any unusual amount of coal-dust. Third- 
 ly, and most conclusively, experiment has shown 
 that the coal-dust can not penetrate to the lungs. 
 Claude Bernard, the brilliant experimenter, tied a 
 bladder containing a quantity of powdered char- 
 coal to the muzzle of a rabbit. Whenever the an- 
 imal breathed, the powder within the bladder was 
 seen to be agitated. Except during feeding-time 
 the bladder was kept constantly on, so that the 
 animal breathed only this dusty air. If the powder 
 could have escaped the vigilance of the cilia and 
 got into the lungs, this was a good occasion. But 
 when the rabbit was killed and opened, many days 
 afterward, no powder whatever was found in the 
 lungs or bronchial tubes ; several patches were col- 
 lected about the nostrils and throat, but the cilia 
 had acted as a strainer, keeping all particles from 
 the air-tubes. 
 
 The swimming apparatus of the Opalina has led 
 us far away from the little animal who has been 
 
STUDIES IN ANIMAL LIFE. 21 
 
 feeding while we have been lecturing. At the men- 
 tion of feeding you naturally look for the food that 
 is eaten, the mouth and stomach that eat. But I 
 hinted just now that this ethereal creature dispenses 
 with a stomach, as too gross for its nature, and of 
 course, by a similar refinement, dispenses with a 
 mouth. Indeed, it has no organs whatever except 
 the cilia just spoken of. The same is true of several 
 of the Infusoria, for you must know that naturalists 
 no longer recognize the complex organization which 
 Ehrenberg fancied he had detected in these micro- 
 scopic beings. If it pains you to relinquish the 
 piquant notion of a microscopic animalcule having 
 a structure equal in complexity to that of the ele- 
 phant, there will be ample compensation in the 
 notion which replaces it, the notion of an ascending 
 series of animal organisms, rising from the struc- 
 tureless amoeba to the complex frame of a mammal. 
 On a future occasion we shall see that, great as 
 Ehrenberg's services have been, his interpretations 
 of what he saw have one by one been replaced by 
 truer notions. His immense class of Infusoria has 
 been, and is constantly being, diminished; many 
 of his animals turn out to be plants ; many of them 
 embryos of worms ; and some of them belong to 
 the same divisions of the animal kingdom as the 
 oyster and the shrimp that is to say, they range 
 with the Mollusks and Crustaceans. In these, of 
 course, there is a complex organization ; but in the 
 Infusoria, as now understood, the organization is 
 
22 STUDIES IN ANIMAL LIFE. 
 
 extremely simple. No one now believes the clear 
 spaces visible in their substance to be stomachs, as 
 Ehrenberg believed ; and the idea of the Polygas- 
 trica, or many-stomached Infusoria, is abandoned. 
 No one now believes the colored specs to be eyes, 
 because, not to mention the difficulty of conceiving 
 eyes where there is no nervous system, it has been 
 found that even the spores of some plants have 
 these colored specs, and they are assuredly not eyes. 
 If, then, we exclude the highly-organized Ratifera, 
 or "Wheel Animalcules," which are genuine Crus- 
 tacea, we may say that all Infusoria, whether they 
 be the young of worms or not, are of very simple 
 organization. 
 
 And this leads us to consider what biologists 
 mean by an organ : it is a particular portion of the 
 body set apart for the performance of some particu- 
 lar function. The whole process of development is 
 this setting apart for special purposes. The start- 
 ing-point of Life is a single cell that is to say, a 
 microscopic sac, filled with liquid and granules, and 
 having within it a. nucleus, or smaller sac. Paley 
 has somewhere remarked that in the early stages 
 there is no difference discernible between a frog and 
 a philosopher. It is very true truer than he con- 
 ceived. In the earliest stage of all, both the Ba- 
 trachian and the Philosopher are nothing but single 
 cells, although the one cell will develop into an 
 Aristotle or a Newton, and the other will get no 
 higher than the cold, damp, croaking animal which 
 
STUDIES IN ANIMAL LIFE. 23 
 
 boys will pelt, anatomists dissect, and Frenchmen 
 eat. From the starting-point of a single cell this 
 is the course taken : the cell divides itself into two, 
 the two become four, the four eight, and so on, till 
 a mass of cells is formed not unlike the shape of 
 a mulberry. This mulberry-mass then becomes a 
 sac, with double envelopes or walls ; the inner wall, 
 turned toward the yelk, or food, becomes the assim- 
 ilating surface for the whole ; the outer wall, turned 
 toward the surrounding medium, becomes the sur- 
 face which is to bring frog and philosopher into 
 contact and relation with the external world the 
 Non-Ego, as the philosopher in after life will call it. 
 Here we perceive the first grand " setting apart," or 
 differentiation, has taken place ; the embryo having 
 an assimilating surface, which has little to do with 
 the external world, and a sensitive, contractile sur- 
 face, which has little to do with the preparation and 
 transport of food. The embryo is no longer a mass 
 of similar cells ; it is already become dissimilar, dif- 
 ferent, as respects its inner and outer envelope. 
 But these envelopes are at present uniform; one 
 part of each is exactly like the rest. Let us, there- 
 fore, follow the history of Development, and we 
 shall find that the inner wall gradually becomes un- 
 like itself in various parts, and that certain organs, 
 constituting a very complex apparatus of Digestion, 
 Secretion, and Excretion, are all one by one wrought 
 out of it by a series of metamorphoses or differentia- 
 tions. The inner wall thus passes from a simple 
 
24 STUDIES Itf ANIMAL LIFE. 
 
 assimilating surface to a complex apparatus serving 
 the functions of vegetative life. 
 
 Now glance at the outer wall : from it also vari- 
 ous organs have gradually been wrought ; it has de- 
 veloped into muscles, nerves, bones, organs of sense, 
 and brain all these from a simple homogeneous 
 membrane ! 
 
 With this bird's-eye view of the course of devel- 
 opment you will be able to appreciate the grand 
 law first clearly enunciated by Goethe and Yon 
 Baer as the law of animal life, namely, that devel- 
 opment is always from the general to the special, 
 from the simple to the complex, from the homoge- 
 neous to the heterogeneous, and this by a gradual 
 series of differentiations* Or, to put it into the 
 music of our deeply meditative Tennyson, 
 
 "All nature widens upward. Evermore 
 
 The simpler essence lower lies : 
 More complex is more perfect owning more 
 Discourse, more widely wise." 
 
 You are now familiarized with the words " differ- 
 entiation" and "development," so often met with 
 in modern writers, and have gained a distinct idea 
 of what an " organ" is, so that, on hearing of an 
 animal without organs, you will at once conclude 
 that in such an animal there has been no setting 
 apart of any portion of the body for special pur- 
 poses, but that all parts serve all purposes indis- 
 
 * GOETHE: Zur Morphologic, 1807. VON BAER: ZurEntwick- 
 elungsgeschichte, 1 828. Part I., p. 158. 
 
OF THE 
 STUDIES IN AJSTIMAL LI^TJ JJ I V H?l S I T 3f 
 
 criminately. Here is our Qpalina,Nfop'' example, 
 without mouth, or stomach, or any other organ. It 
 is an assimilating surface in every part; in every 
 part a breathing, sensitive surface. Living on liquid 
 food, it does not need a mouth to seize, or a stomach 
 to digest such food. The liquid, or gas, passes 
 through the Opalina's delicate skin by a process 
 which is called endosmosis ; it there serves as food ; 
 and the refuse passes out again by a similar process, 
 called exosmosis. This is the way in which many 
 animals and all plants are nourished. The cell at 
 the end of a rootlet, which the plant sends burrow- 
 ing through the earth, has no mouth to seize, no 
 open pores to admit the liquid that it needs ; never- 
 theless, the liquid passes into the cell through its 
 delicate cell-wall, and passes from this cell to other 
 cells upward from the rootlet to the bud. It is in 
 this way, also, that the Opalina feeds: it is all- 
 mouth, no-mouth ; all-stomach, no-stomach. Every 
 part of its body performs the functions which in 
 more complex animals are performed by organs 
 specially set apart. It feeds without mouth, breathes 
 without lungs, and moves without muscles. 
 
 The Opalina, as I said, is a parasite. It may be 
 found in various animals, and almost always in the 
 frog. You will perhaps ask why it should be con- 
 sidered a parasite ? why may it not have been swal- 
 lowed by the frog in a gulp of water ? Certainly 
 nothing would have been easier. But, to remove 
 your doubts, I open the skull of this frog, and care- 
 B 
 
26 
 
 STUDIES IN ANIMAL LIFE. 
 
 fully remove a drop of the liquid found inside, 
 which, on being brought under a microscope, we 
 shall most probably find containing some animal- 
 cules, especially those named Monads. These were 
 not swallowed. They live in the cerebro-spinal 
 fluid, as the Opalina lives in the digestive tube. 
 Nay, if we extend our researches, we shall find 
 that various organs have their various parasites. 
 Here, for instance, is a parasitic worm from the 
 
 frog's bladder. Place it 
 under the microscope with 
 a high power, and behold ! 
 It is called Polystomum 
 many-mouthed, or, more 
 properly, many-suckered. 
 You are looking at the un- 
 der side, and will observe 
 six large suckers with their 
 starlike clasps (e), and the 
 horny instrument (/) with 
 which the animal bores its 
 way. At a there is anoth- 
 er sucker, which serves 
 also as a mouth ; at b you 
 perceive the rudiment of a 
 gullet, and at d the repro- 
 ductive organs. But pay attention to the pretty 
 branchings of the digestive tube (c), which ramifies 
 through the body like a blood-vessel. 
 
 This arrangement of the digestive tube is found 
 
 Fig. 3. POLYSTOMUM INTEGEEEI- 
 MTTM, magnified. 
 
STUDIES IN ANIMAL LIFE. 27 
 
 in many animals, and is often mistaken for a system 
 of blood-vessels. In one sense this is correct, for 
 these branching tubes are carriers of nutriment, and 
 the only circulating vessels such animals possess ; 
 but the nutriment is chyme, not blood : these simple 
 animals have not arrived at the dignity of blood, 
 which is a higher elaboration of the food, fitted for 
 higher organisms. 
 
 Thus may our frog, besides its own marvels, af- 
 ford us many " authentic tidings of invisible things," 
 and is itself a little colony of life. Nature is eco- 
 nomic as well as prodigal of space. She fills the il- 
 limitable heavens with planetary and starry grand- 
 eurs, and the tiny atoms moving over the crust of 
 earth she makes the homes of the infinitely little. 
 Far as the mightiest telescope can reach, it detects 
 worlds in clusters, like pebbles on the shore of in- 
 finitude ; deep as the microscope can penetrate, it 
 detects life within life, generation within genera- 
 tion, as if the very universe itself were not vast 
 enough for the energies of life ! 
 
 That phrase, generation within generation, was 
 not a careless phrase ; it is exact. Take the tiny 
 insect (Aphis) which, with its companions, crowds 
 your rose-tree ; open it, in a solution of sugar- water, 
 under your microscope, and you will find in it a 
 young insect nearly formed ; open that young in- 
 sect with care, and you will find in it, also, another 
 young one, less advanced in its development, but 
 perfectly recognizable to the experienced eye ; and 
 
28 STUDIES IN ANIMAL LIFE. 
 
 beside this embryo you will find many eggs, which 
 would in time become insects ! 
 
 Or take that lazy water-snail (Paludina vivipara\ 
 first made known to ^science by the great Swam- 
 merdamm, the incarnation of patience and exact- 
 ness, and you will find, as he found, forty or fifty 
 young snails in various stages of development ; and 
 you will also find, as he found, some tiny worms, 
 which, if you cut them open, will suffer three or 
 four infusoria to escape from the opening.* In your 
 astonishment you will ask, "Where is this to end ? 
 
 The observation recorded by Swammerdamm, 
 like so many others of this noble worker, fell into 
 neglect, but modern investigators have made it the 
 starting-point of a very curious inquiry. The worms 
 he found within the snail are now called Cercaria 
 sacs, because they contain the Cercarice, once classed 
 as Infusoria, and which are now known to be the 
 early forms of parasitic worms inhabiting the di- 
 gestive tube and other cavities of higher animals. 
 These Cercarice have vigorous tails, with which they 
 swim through the water like tadpoles, and, like tad- 
 poles, they lose their tails in after life. But how, 
 think you, did these sacs containing Cercarice get 
 into the water-snails? "By spontaneous genera- 
 tion," formerly said the upholders of that hypothe- 
 sis, and those who condemned the hypothesis were 
 forced to admit they had no better explanation. It 
 was a mystery which they preferred leaving unex- 
 
 * SWAMMERDAMM. Bibel der Natur, p. 75-77. 
 
STUDIES IN ANIMAL LIFE. 29 
 
 plained rather than fly to spontaneous generation. 
 And they were right. The mystery has at length 
 been cleared up.* I will endeavor to bring togeth- 
 er the scattered details, and narrate the curious 
 story. 
 
 Under the eyelids of geese and ducks may be 
 constantly found a parasitic worm (of the Trematode 
 order), which naturalists have christened Monosto- 
 mum mutdbile Single-mouth, Changeable. This 
 worm brings forth living young, in the likeness of 
 active Infusoria, which, being covered with cilia, 
 swim about in the water as we saw the Opalina 
 swim. Here is a portrait of one. 
 
 Fig. 4 A, EMBBYO OP MONOSTOMTJM MUTABLLE. 
 B, Cercaria sac, just set free. 
 
 a, mouth; 6, pigment spots; c, sac magnified. 
 
 Each of these animalcules develops a sac in its 
 interior. The sac you may notice in the engraving. 
 
 * By VON SIEBOLD. See his interesting work, Ueber die Band- 
 und-Blasenwilrmer . It has been translated by HUXLEY, and ap- 
 pended to the translation of KUECHENMEISTER on Parasites, pub- 
 lished by the Sydenham Society. 
 
30 
 
 STUDIES IN ANIMAL LIFE. 
 
 Having managed to get into the body of the water- 
 snail, the animalcule's part in the drama is at an 
 end. It dies, and in dying liberates the sac, which 
 is very comfortably housed and fed 
 by the snail. If you examine this sac 
 (Fig. 5), you will observe that it has 
 a mouth and digestive tube, and is, 
 therefore, very far from being, what its 
 name imports, a mere receptacle ; it is 
 an independent animal, and lives an 
 independent life. It feeds generously 
 
 Fig. 5. CEBCABIA , . . , ., -, , 
 
 SAC. on the juices of the snail, and, -having 
 fed, thinks generously of the coming 
 generations. It was born inside the 
 different Stages animalcule ; why should it not in turn 
 give birth to children of its own ? To 
 found a dynasty, to scatter progeny over the boun- 
 teous earth, is a worthy ambition. The mysterious 
 agency of reproduction begins in 
 this sac-animal, and in a short 
 while a brood of Cercarice move 
 within it. The sac bursts, and 
 the brood escapes. But how is 
 this? The children are by no 
 means the " very image" of their 
 parent. They are not sacs, nor 
 in the least resembling sacs, as 
 you see (Fig. 6). 
 
 They have tails, and suckers, 
 and sharp boring instruments, 
 
 Fig. 6. CERCABIA DEVEL- 
 OPED. 
 
 A, mouth; B, B, B, excre- 
 tory organ; C, pigment 
 spots ; D, tail. 
 
STUDIES 1ST ANIMAL LIFE. 31 
 
 with other organs which their parent was without. 
 To look at them you would as soon suspect a shrimp 
 to be the progeny of an oyster, as these to be the 
 progeny of the sac-animal. And what makes the 
 paradox more paradoxical is, that not only are the 
 Cercarios, unlike their parent, but their parent was 
 equally unlike its parent, the. embryo of Monosto- 
 mum (compare Fig. 4). However, if we pursue this 
 family history, we shall find the genealogy rights 
 itself at last, and that this Cercaria will develop in 
 the body of some bird into a Monostomum mutdbile 
 like its ancestor. Thus the worm produces an an- 
 imalcule, which produces a sac-animal, which pro- 
 duces a Cercaria, which becomes a worm exactly 
 resembling its great-grandfather. 
 
 One peculiarity in this history is, that while the 
 Monostomum produces its young in the usual way, 
 the two intermediate forms are produced by a process 
 of budding analogous to that observed in plants. 
 Plants, as you know, are reproduced in two ways 
 from the seed and from the bud. For seed- 
 reproduction peculiar organs are necessary; for 
 bud-reproduction there is no such differentiation 
 needed: it is simply an outgrowth. The same is 
 true of many animals ; they also bud like plants, 
 and produce seeds (eggs) like plants. I have else- 
 where argued that the two processes are essentially 
 identical, and that both are but special forms of 
 growth.* Not, however, to discuss so abstruse a 
 
 * Seaside Studies, p. 308 et sq. 
 
32 STUDIES IN ANIMAL LIFE. 
 
 question here, let us merely note that the Monosto- 
 mum, into which the Cercaria will develop, produces 
 eggs, from which young will issue ; the second gen- 
 eration is not produced from eggs, but by internal 
 budding; the third generation is likewise budded 
 internally, but it, on acquiring maturity, will pro- 
 duce eggs. For this maturity, it is indispensable 
 that the Cercaria should be swallowed by some bird 
 or animal ; only in the digestive tube can it acquire 
 its producing condition. How is it to get there ? 
 The ways are many ; let us witness one : 
 
 In this watch-glass of water we have several Cer- 
 carice swimming about. To them we add three or 
 four of those darting, twittering insects which you 
 have seen in every vase of pond- water, and have 
 learned to be the larvae or early forms of the 
 Ephemeron. The Cercaricz cease napping the water 
 with their impatient tails, and commence a severe 
 scrutiny of the strangers. When Odry, in the riot- 
 ous farce Les Saltimbanques, finds a portmanteau, he 
 exclaims, ".Un mallei ce doit etre d moil" ("Surely 
 this must belong to me!") This seems to be the 
 theory of property adopted by the Cercaria: "An 
 insect! surely this belongs to me!" Accordingly 
 every one begins creeping over the bodies of the 
 Ephemera, giving an interrogatory poke with the 
 spine, which will pierce the first soft place it can 
 detect. Between the segments of the insect's armor 
 a soft and pierceable spot is found ; and now, lads, 
 to work! Onward they bore, never relaxing in 
 
STUDIES IN ANIMAL LIFE. 33 
 
 their efforts till a hole is made large enough for 
 them to slip in by elongating their bodies. Once 
 in, they dismiss their tails as useless appendages, 
 and begin what is called the process of encysting 
 that is, of rolling themselves up into a ball, and se- 
 creting a mucus from their surface which hardens 
 round them like a shell. Thus they remain snugly 
 ensconced in the body of the insect, which in time 
 develops into a fly, hovers over the pond, and is 
 swallowed by some bird. The fly is digested, and 
 the liberated Cercaria finds itself in comfortable 
 quarters, its shell is broken, and its progress to ma- 
 turity is rapid. 
 
 Yon Siebold's description of another form of em- 
 igration he has observed in parasites will be read 
 with interest. "For a long time," he says, "the 
 origin of the thread-worm, known as Filaria insec- 
 torumj that lives in the cavity of the bodies of adult 
 and larval insects, could not be accounted for. Shut 
 up within the abdominal cavity of caterpillars, grass- 
 hoppers, beetles, and other insects, these parasites 
 were supposed to originate by spontaneous genera- 
 tion under the influence of wet weather or from de- 
 cayed food. Helminthologists (students of parasitic 
 worms) were obliged to content themselves with 
 this explanation, since they were unable to find a 
 better. Those who dissected these thread-worms, 
 and submitted them to a careful inspection, could 
 not deny the probability, since it was clear that they 
 contained no trace of sexual organs. But, on di- 
 B2 
 
34: STUDIES IN ANIMAL LIFE. 
 
 recting my attention to these entozoa, I became 
 aware of the fact that they were not true Filarice, at 
 all, but belonged to a peculiar family of thread- 
 worms, embracing the genera of Gordius and Her- 
 mis. Furthermore, I convinced myself that these 
 parasites wander away when full grown, boring 
 their way from within through any soft place in 
 the body of their host, and creeping out through 
 the opening. These parasites do not emigrate be- 
 cause they are uneasy, or because the caterpillar is 
 sickly, but from that same internal necessity which 
 constrains the horsefly to leave the stomach of the 
 horse where he has been reared, or which moves 
 the gadfly to work its way out through the skin of 
 the ox. The larvae of both these insects creep forth 
 in order to become chrysalises, and thence to pro- 
 ceed to their higher and perfect condition. I have 
 demonstrated that the perfect, full-grown, but sex- 
 less thread- worms of insects are in like manner 
 moved by their desire to wander out of their pre- 
 vious homes in order to enter upon a new period 
 of their lives, which ends in the development of 
 their sex. As they leave the bodies of their hosts, 
 they fall to the ground and crawl away into the 
 deeper and moister parts of the soil. Thread- 
 worms found in the damp earth, in digging up gar- 
 dens and cutting ditches, have often been brought 
 to me which presented no external distinctions from 
 the thread- worms of insects. This suggested to me 
 that the wandering thread- worms of insects might 
 
STUDIES IN" ANIMAL LIFE. 35 
 
 instinctively bury themselves in damp ground, and 
 I therefore instituted a series of experiments by 
 placing the newly-emigrated worms in flower-pots 
 filled with damp earth. To my delight, I soon per- 
 ceived that they began to bore with their heads into 
 the earth, and by degrees drew themselves entirely 
 in. For many months I kept the earth in the flow- 
 er-pots moderately moist, and, on examining the 
 worms from time to time, I found they had gradu- 
 ally attained their sex-development, and eggs were 
 deposited in hundreds. Toward the conclusion of 
 winter I could succeed in detecting the commencing 
 development of the embryos in these eggs. By the 
 end of spring they were fully formed, and many of 
 them, having left their shells, were to be seen creep- 
 ing about the earth. I now conjectured that these 
 young worms would be impelled by their instincts 
 to pursue a parasitic existence, and to seek out an 
 animal to inhabit and to grow to maturity in ; and 
 it seemed not improbable that the brood I had 
 reared would, like their parents, thrive best in the 
 caterpillar. In order, therefore, to induce my young 
 brood to immigrate, I procured a number of very 
 small caterpillars, which the first spring sunshine 
 had just called into life. For the purpose of my 
 experiment, I filled a watch-glass with damp earth, 
 taking it from among the flower-pots where the 
 thread-worms had wintered. Upon this I placed 
 several of the young caterpillars." The result was 
 as he expected; the caterpillars were soon bored 
 
36 STUDIES IN ANIMAL LIFE. 
 
 into by the worms, and served them at once as food 
 and home.* 
 
 Frogs and parasites, worms and infusoria are 
 these worth the attention of a serious man ? They 
 have a less imposing appearance than planets and 
 asteroids I admit, but they are nearer to us, and ad- 
 mit of being more intimately known, and, because 
 they are thus accessible, they become more import- 
 ant to us. The life that stirs within us is also the 
 life within them. It is for this reason, as I said at 
 the outset, that, although man's noblest study must 
 always be man, there are other studies less noble, 
 yet not therefore ignoble, which must be pursued, 
 even if only with a view to the perfection of the 
 noblest. Many men, and these not always the ig- 
 norant, whose scorn of what they do not under- 
 stand is always ready, despise the labors which do 
 not obviously and directly tend to moral or political 
 advancement. Others there are who, fascinated by 
 the grandeur of Astronomy and Geology, or by the 
 immediate practical results of Physics and Chem- 
 istry, disregard all microscopic research as little bet- 
 ter than dilettante curiosity. But I can not think 
 any serious study is without its serious value to the 
 human race; and I know that the great problem 
 of Life can never be solved while we are in igno- 
 rance of its simpler forms. Nor can any thing be 
 more unwise than the attempt to limit the sphere 
 
 * VON SIEBOLD : Ueber Band-und-Blasenwurmer. Translated 
 by HUXLEY. 
 
STUDIES IN ANIMAL LIFE. 37 
 
 of human inquiry, especially by applying the test 
 of immediate utility. All truths are related ; and, 
 however remote from our daily needs some partic- 
 ular truth may seem, the time will surely come 
 when its value will be felt. To the majority of our 
 countrymen during the Eevolution, when the con- 
 duct of James seemed of incalculable importance, 
 there would have seemed something ludicrously ab- 
 surd in the assertion that the newly-discovered dif- 
 ferential calculus was infinitely more important to 
 England and to Europe than the fate of all the dy- 
 nasties; and few things could have seemed more 
 remote from any useful end than this product of 
 mathematical genius ; yet it is now clear to every 
 one that the conduct of James was supremely insig- 
 nificant in comparison with this discovery. I do 
 not say that men were unwise to throw themselves 
 body and soul into the Eevolution ; I only say they 
 would have been unwise to condemn the researches 
 of mathematicians. 
 
 Let all who have a longing to study Nature in 
 any of her manifold aspects do so without regard 
 to the sneers or objections of men whose tastes and 
 faculties are directed elsewhere. From the illumi- 
 nation of many minds on many points Truth must 
 finally emerge. Man is, in Bacon's noble phrase, 
 the minister and interpreter of Nature ; let him be 
 careful lest he suffer this ministry to sink into a 
 priesthood, and this interpretation to degenerate 
 into an immovable dogma. The suggestions of 
 
38 STUDIES IN ANIMAL LIFE. 
 
 apathy and the prejudices of ignorance have at all 
 times inspired the wish to close the temple against 
 new comers. Let us be vigilant against such sug- 
 gestions, and keep the door of the temple ever 
 open. 
 
STUDIES IN ANIMAL LIFE. 39 
 
 CHAPTER H. 
 
 Ponds and Rock-pools. Oar necessary Tackle. Wimbledon 
 Common. Early Memories. Gnat Larvae. Entomostraca 
 and their Paradoxes. Races of Animals dispensing with the 
 sterner Sex. Insignificance of Males. Volvox Globator : is it 
 an Animal ? Plants swimming like Animals. Animal Retro- 
 gressions. The Dytiscus and its Larva. The Dragon-fly Lar- 
 va. Mollusks and their Eggs. Polypes, and how to find them. 
 A new Polype, Hydra rubra. Nest-building Fish. Con- 
 tempt replaced by Reverence. 
 
 THE day is bright with a late autumn sun ; the 
 sky is clear with a keen autumn wind, which lashes 
 our blood into a canter as we press against it, and 
 the cantering blood sets the thoughts into hurrying 
 excitement. Wimbledon Common is not far off; 
 its five thousand acres of undulating heather, furze, 
 and fern tempt us across it, health streaming in at 
 every step as we snuff the keen breeze. "We are 
 tempted also to bring net and wide-mouthed jar, to 
 ransack its many ponds for visible and invisible 
 wonders. 
 
 Ponds, indeed, are not so rich and lovely as rock- 
 pools ; the heath is less alluring than the coast 
 our dear-loved coast, with its gleaming mystery, the 
 sea, and its sweeps of sand, its reefs, its dripping 
 boulders. I admit the comparative inferiority of 
 ponds, but, you see, we are not near the coast, and 
 
40 STUDIES IN ANIMAL LIFE. 
 
 the heath is close at hand. Nay, if the case were 
 otherwise, I should object to dwarfing comparisons. 
 It argues a pitiful thinness of nature (and the major- 
 ity in this respect are lean) when present excellence 
 is depreciated because some greater excellence is to 
 be found elsewhere. We are not elsewhere; we 
 must do the best we can with what is here. Be- 
 cause ours is not the Elizabethan age, shall we ex- 
 press no reverence for our great men, but reserve 
 it for Shakspeare, Bacon, and Ealeigh, whose tra- 
 ditional renown must overshadow our contempo- 
 raries? Not so. To each age its honor. Let us 
 be thankful for all greatness, past or present, and 
 never speak slightingly of noble work or honest 
 endeavor because it is not, or we choose to say it is 
 not, equal to something else. No comparisons, then, 
 I beg. If I said ponds were finer than rock-pools, 
 you might demur ; but I only say ponds are excel- 
 lent things, let us dabble in them; ponds are rich 
 in wonders, let us enjoy them. 
 
 And, first, we must look to our tackle. It is ex- 
 tremely simple. A landing-net, lined with muslin ; 
 a wide-mouthed glass jar, say a foot high and six 
 inches in diameter, but the size optional, with a bit 
 of string tied under the lip, and forming a loop over 
 the top, to serve as a handle, which will let the jar 
 swing without spilling the water ; a camel's-hair 
 brush ; a quinine bottle, or any wide-mouthed phi- 
 al, for worms and tiny animals which you desire to 
 keep separated from the dangers and confusions of 
 
STUDIES IN ANIMAL LIFE. 41 
 
 the larger jar; and when to these a pocket lens is 
 added, our equipment is complete. 
 
 As we emerge upon the common and tread its 
 springy heather, what a wild wind dashes the hair 
 into our eyes, and the blood into our cheeks ! and 
 what a fine sweep of horizon lies before us ! The 
 lingering splendors and the beautiful decays of au- 
 tumn vary the scene, and touch it with a certain 
 pensive charm. The ferns mingle harmoniously 
 their rich browns with the dark green of the furze, 
 now robbed of its golden summer glory, but still 
 pleasant to the eye and exquisite to memory. The 
 gaunt wind-mill on the rising ground is stretching 
 its stiff, starred arms into the silent air, a land- 
 mark for the wanderer a land-mark, too, for the 
 wandering mind, since it serves to recall the dim 
 early feelings and sweet broken associations of a 
 childhood when we gazed at it with awe, and listen- 
 ed to the rushing of its mighty arms. Ah ! well 
 may the mind with the sweet insistance of sadness 
 linger on those scenes of the irrecoverable past, and 
 try, by lingering there, to feel that it is not wholly 
 lost, wholly irrecoverable, vanished forever from the 
 Life which, as these decays of autumn and these 
 changing trees too feelingly remind us, is gliding 
 away, leaving our cherished ambitions still unful- 
 filled, and our deeper affections still but half ex-, 
 pressed. The vanishing visions of elapsing life 
 bring with them thoughts which lie too deep for 
 tears, and this wind-mill recalls such visions by 
 
42 STUDIES IN ANIMAL LIFE. 
 
 the subtle laws of association. Let us go toward it, 
 and stand once more under its shadow. See the in- 
 telligent and tailless sheep-dog which bounds out at 
 our approach, eager and minatory ; now his quick 
 eye at once recognizes that we are neither tramps 
 nor thieves, and he ceases barking to commence a 
 lively interchange of sniffs and amenities with our 
 Pug, who seems also glad of a passing interchange 
 of commonplace remarks. While these dogs travel 
 over each other's minds, let us sun ourselves upon 
 this bench, and look down on the embrowned val- 
 ley, with its gipsy encampment, or abroad on the 
 purple Surrey hills, or the varied-tinted trees of 
 Combe Wood and Richmond Park. There are not 
 many such prospects so near London. But, in 
 spite of the sun, we must not linger here : the wind 
 is much too analytical in its remarks ; and, more- 
 over, we came out to hunt. 
 
 Here is a pond with a mantling surface of green 
 promise. Dip the jar into the water. Hold it now 
 up to the light, and you will see an immense varie- 
 ty of tiny animals swimming about. Some are 
 large enough to be recognized at once; others re- 
 quire a pocket lens, unless familiarity has already 
 enabled you to infer the forms you can not distinct- 
 ly see. Here (Fig. 7) are two larvae (or grubs) of 
 the common gnat. That large-headed fellow (A) 
 bobbing about with such grotesque movements is 
 very near the last stage of his metamorphosis, 
 and to-morrow, or the next day, you may see him 
 
STUDIES IN ANIMAL LIFE. 
 
 Fig. 7. LABV./E OP THE GNAT in two different stages of development 
 (magnified). 
 
 cast aside this mask (larva means a mask), and 
 emerge a perfect insect. The other (B) is in a 
 much less matured condition, but leads an active 
 predatory life, jerking through the water, and fast- 
 ening to the stems of weed or sides of the jar by 
 means of the tiny hooks at the end of its tail. The 
 hairy appendage forming the angle is not another 
 tail, but a breathing apparatus. 
 
 Observe, also, those grotesque Entomostraca* 
 popularly called "water-fleas," although, as you 
 perceive, they have little resemblance in form or 
 manners to our familiar (somewhat too familiar) 
 bed-fellows. This (Fig. 8) is a Cyclops, with only 
 one eye in the centre of its forehead, and carrying 
 two sacs, filled with eggs, like panniers. You ob- 
 
 * Entomostraca (from entomos, an insect, and ostracon, a shell) 
 are not really insects, but belong to the same large group of ani- 
 mals as the lobster, the crab, or the shrimp i. e., crustaceans. 
 
44 
 
 STUDIES IN ANIMAL LIFE. 
 
 serve he has no legs ; or, 
 rather, legs and arms are 
 
 Fig. 8 CYCLOPS. 
 
 a, large antennae ; 6, smaller do. ; 
 c, egg-sacs (magnified). 
 
 Fig. 9. DAPHNIA. 
 
 a, pulsatile sac, or heart ; 6, eggs ; 
 c, digestive tube (magnified). 
 
 hoisted up to the head, and become antennae (or 
 feelers). Here (Fig. 9) is a Daphnia, grotesque 
 enough, throwing up his arms in astonished awk- 
 wardness, and keeping 
 his legs actively at work 
 inside the shell as res- 
 pirators, in fact. Here 
 (Fig. 10) is a Eurycer- 
 cus, less grotesque, and 
 with a much smaller eye. 
 Talking of eyes, there is 
 
 Fig. 10. EUEYCEKCUS. 
 a, heart ; &, eggs ; c, digestiv< 
 (magnified). 
 
 tube 
 
 one of these Entomos- 
 traca, named Polyphemus, whose head is all eye; 
 and another, named Caligus, who has no head at all. 
 Other paradoxes and wonders are presented by this 
 interesting group of animals ;* but they all sink 
 
 * The student will find ample information in BAIRD'S British 
 Entomostraca, published by the Kay Society. 
 
STUDIES IN ANIMAL LIFE. 45 
 
 into insignificance beside the paradox of the ama- 
 zonian entomostracon, the Apus a race which dis- 
 penses with masculine services altogether, a race of 
 which there are no males ! 
 
 I well remember the pleasant evening on which 
 I first made the personal acquaintance of this ama- 
 zon. It was at Munich, and in the house of a cele- 
 brated naturalist, in whose garden an agreeable as- 
 semblage of poets, professors, and their wives saun- 
 tered in the light of a setting sun, breaking up into 
 groups and tetes-d-tetes, to re-form into larger groups. 
 We had taken coffee under the branching coolness 
 of trees, and were now loitering through the brief 
 interval till supper. Our host had just returned 
 from an expedition of some fifty miles to a particu- 
 lar pond, known to be inhabited by the Apus. He 
 had made this journey because the race, although 
 prolific, is rare, and is not to be found in every spot. 
 For three successsive years had he gone to the same 
 pond in quest of the male ; but no male was to be 
 found among thousands of egg-bearing females, 
 some of which he had brought away with him, and 
 was showing us. We were amused to see them 
 swimming about, sometimes on their backs, using 
 their long oars, sometimes floating, but always in- 
 cessantly agitating the water with their ten pairs 
 of breathing legs ; and the ladies, gathered round 
 the jar, were hugely elated at the idea of animals 
 getting rid altogether of the sterner sex clearly a 
 useless encumbrance in the scheme of things ! 
 
46 STUDIES IN ANIMAL LIFE. 
 
 The fact that no male Apus has yet been found 
 is not without precedent. Leon Dufour, the cele- 
 brated entomologist, declares that he never found 
 the male of the gall insect (Diplolepis gallce tinctorice), 
 though he has examined thousands : they were all* 
 females, and bore well-developed eggs on emerging 
 from the gall-nut in which their infancy had pass- 
 ed. In two other species of gall insect Cynips di- 
 visa and Cynips folii Hartig says he was unable to 
 find a male ; and he examined about thirteen thou- 
 sand. Brongniart never found the male of another 
 entomostracon (Limnadia gigas), nor could Jurine 
 find that of our Polyphemus. These negatives 
 prove, at least, that if the males exist at all, they 
 must be excessively rare, and their services can be 
 dispensed with ; a conclusion which becomes accept- 
 able when we learn that bees, plant-lice (Aphides), 
 and our grotesque friend Daphnia (Fig. 9) lay eggs 
 which may be reared apart, will develop into fe- 
 males, and these will produce eggs which will in 
 turn produce other females, and so on, generation 
 after generation, although each animal be reared in 
 a vessel apart from all others. 
 
 While on this subject, I can not forbear making 
 a reflection. It must be confessed that our sex cuts 
 but a poor figure in some great families. If the 
 male is in some families grander, fiercer, more splen- 
 did, and more highly endowed than the female, this 
 occasional superiority is more than counterbalanced 
 by the still greater inferiority of the sex in other 
 
OF THE 
 STUDIES IN ANIMAL LfIT Jjf J "^ H51 5 
 
 families. The male is often but a contemptible 
 partner, puny in size, insignificant in powers, stint- 
 ed even of a due allowance of organs. If the pea- 
 cock and the pheasant swagger in greater splendor, 
 what a pitiful creature is the male falcon I no fal- 
 coner will look at him. And what is the drone 
 compared with the queen bee, or even with the 
 workers ? What figure does the male spider make 
 beside his large and irascible female, who not un- 
 frequently eats him ? Nay, worse than this, what 
 can be said for the male Eotifer, the male Barnacle, 
 the male Lernaea gentlemen who can not even 
 boast of a perfect digestive apparatus, sometimes 
 not of a digestive organ at all ? Nor is this mea- 
 greness confined to the digestive system only. In 
 some cases, as in some male Kotifers, the usual or- 
 gans of sense and locomotion are wanting ;* and in 
 a parasitic Lernaea, the degradation is moral as well 
 as physical : the female lives in the gills of a fish, 
 sucking its juices, and the ignoble husband lives as 
 a parasite upon her ! 
 
 But this digression is becoming humiliating, and 
 meanwhile our hands are getting benumbed with 
 cold. In spite of that, I hold the jar up to the 
 light, and make a background of my forefingers, to 
 throw into relief some of the transparent animals. 
 Look at those green crystal spheres sailing along 
 
 v * Compare GEGENBAUR: Gnmdzuge der vergldchende Anato- 
 rnie, 1859, p. 229 und 269 ; also LEYDIG iiber Hydatina senta, in 
 Miller's Arckiv, 1857, p. 411. 
 
48 STUDIES IN ANIMAL LIFE. 
 
 Fig. 11. VOLVOX GLOBATOR, with eight volvoces 
 inclosed (magnified). 
 
 with slow revolving motion, like planets revolving 
 through, space, except that their orbits are more ec- 
 centric. Each of these spheres is a Volvox globator. 
 Under the microscope it looks like a crystalline 
 sphere, studded with bright green specks, from each 
 of which arise two cilia (hairs), serving as oars to 
 row the animal through the water. The specks are 
 united by a delicate net-work, which is not always 
 visible, however. Inside this sphere is a fluid, in 
 which several dark green smaller spheres are seen 
 revolving, as the parent sphere revolved in the wa- 
 ter. Press this Yolvox gently under your com- 
 pressorium, or between the two pieces of glass, and 
 you will see these internal spheres, when duly mag- 
 nified, disclose themselves as identical with their 
 parent ; and inside them smaller Volvoces are 
 seen. This is one of the many illustrations of life 
 within life, of which something was said in the last 
 chapter. 
 
STUDIES IN ANIMAL LIFE. 49 
 
 Nor is this all. Those bright green specks which 
 stud the surface, if examined with high powers, will 
 turn out to be, not specks, but animals,* and, as Eh- 
 renberg believes (though the belief is but little 
 shared), highly organized animals, possessing a 
 mouth, many stomachs, and an eye. It is right to 
 add that not only are microscopists at variance with 
 Ehrenberg on the supposed organization of these 
 specks, but the majority deny that the Yolvox itself 
 is an animal. Yon Siebold in Germany, and Pro- 
 fessor George Busk and Professor Williamson in 
 England, have argued with so much force against 
 the animal nature of the Yolvox, which they call a 
 plant, that in most modern works you will find this 
 opinion adopted. But the latest of the eminent au- 
 thorities on the subject of Infusoria, in his magnifi- 
 cent work just published, returns to the old idea 
 that the Yolvox is an animal after all, although of 
 very simple organization.f 
 
 The dispute may perhaps excite your surprise. 
 You are perplexed at the idea of a plant (if plant it 
 be) moving about, swimming with all the vigor and 
 dexterity of an animal, and swimming by means of 
 animal organs, the cilia. But this difficulty is one 
 of our own creation. We first employ the word 
 
 * To avoid the equiyoque of calling the parts of an animal, 
 \vhich are capable of independent existence, by the same term as 
 the whole mass, we may adopt HUXLEY'S suggestion, and call all 
 such individual parts zooids instead of animals. DUGES suggested 
 zoonites in the same sense. Sur la Conformite Organique, p. 13. 
 
 i STEIN : Der Organismus der Infusionsthiere, 1859, p. 36-38. 
 
 c 
 
50 STUDIES IN ANIMAL LIFE. 
 
 plant to designate a vast group of objects which 
 have no powers of locomotion, and then ask, with 
 triumph, How can a plant move? But we have 
 only to enlarge our knowledge of plant-life to see 
 that locomotion is not absolutely excluded from it; 
 for many of the simpler plants Confervse and Al- 
 gae can and do move spontaneously in the early 
 stages of their existence : they escape from their 
 parents as free swimming rovers, and do not settle 
 into solid and sober respectability till later in life. 
 In their roving condition they are called, improper- 
 ly enough, " zoospores,"* and once gave rise to the 
 opinion that they were animals in infancy, and be- 
 came degraded into plants as their growth went on. 
 But locomotion is no true mark of animal-nature, 
 neither is fixture to one spot the true mark of plant- 
 nature. Many animals (Polypes, Polyzoa, Barna- 
 cles, Mussels, etc.), after passing a vagabond youth, 
 " settle" once and forever in maturer age, and then 
 become as fixed as plants. Nay, human animals 
 not unfrequently exhibit a somewhat similar me- 
 tempsychosis, and make up for the fitful capricious- 
 ness of wandering youth by the steady severity of 
 their application to business when width of waist- 
 coat and smoothness of cranium suggest a sense of 
 their responsibilities. 
 
 Whether this loss of locomotion is to be regard- 
 ed as a retrogression on the part of the plant or 
 animal which becomes fixed, may be questioned; 
 
 * Zoospores, from zoon, an animal, and s/>oros, a seed. 
 
STUDIES IN ANIMAL LIFE. 51 
 
 but there are curious indications of positive retro- 
 gression from a higher standard in the metamor- 
 phoses of some animals. Thus the beautiful marine 
 worm Terebella, which secretes a tube for itself, and 
 lives in it, fixed to the rock or oyster-shell, has in 
 early life a distinct head, eyes, and feelers ; but in 
 growing to maturity it loses all trace of head, eyes, 
 and even of feelers, unless the beautiful tuft of 
 streaming threads which it waves in the water be 
 considered as replacing the feelers. There are the 
 Barnacles, too, which in the first stage of their ex- 
 istence have three pairs of legs, a very simple single 
 eye, and a mouth furnished with a proboscis. In 
 the second stage they have six pairs of legs, two 
 compound eyes complex in structure, two feelers, 
 but no mouth. In the third, or final stage, their 
 legs are transformed into prehensile organs, they 
 have recovered a mouth, but have lost their feelers, 
 and their two complex eyes are degraded to a single 
 and very simple eye-spot. 
 
 But, to break up these digressions, let us try a 
 sweep with our net. We skim it along the surface, 
 and draw up a quantity of duckweed, dead leaves, 
 bits of stick, and masses of green thread of great 
 fineness, called Conferva by botanists. The water 
 runs away, and we turn over the mass. Here is a 
 fine water-beetle, called the " Water-tiger," from its 
 ferocity (Fig. 12). You would hardly suspect that 
 the slim, big-headed, long-tailed Water-tiger would 
 grow into the squat, small-headed, tailless beetle ; 
 
52 
 
 STUDIES IN ANIMAL LIFE. 
 
 Fig. 12. WATEE BEETLE and its larva. 
 
 nor would you imagine that this Water-tiger would 
 
 be so "high fantas- 
 tical" as to breathe 
 by his tail. Yet he 
 does both, as you will 
 find if you watch 
 him in your aqua- 
 rium. 
 
 Continuing our 
 search, we light up- 
 on the fat, sluggish, 
 ungraceful larva of 
 the graceful and bril- 
 liant Dragon-fly, the 
 falcon of insects (Fig. 
 13). He is useful 
 for dissection, so pop 
 Fig.i3.-DBAGON-FLYL AR v, E : him in. Among the 
 
 A, ordinary aspect; B, with the huge nipper- 
 
 like jaw extended. dead leaves you per- 
 
STUDIES IN ANIMAL LIFE. 
 
 53 
 
 ceive several small leeches, and flat oval Plana- 
 rice, white and brown ; and here also is a jelly- 
 like mass, of pale yellow color, which we know 
 to be a mass of eggs deposited by some shell- 
 fish; and, as there are few objects of greater inter- 
 est than an egg in course of development, we pop 
 the mass in. Here (Fig. 14) are two mollusks, Lim- 
 
 Fig. 14 A, LIMN^US STAGNALIS, or Water-snail. 
 
 B, PLANOBBIS. 
 
 nceus and Planorbis, one of which is probably the 
 parent of those eggs. 
 And here is one which 
 lays no eggs, but brings 
 forth its young alive : it 
 is the Paludina vivipara 
 (Fig. 15), of which we 
 learned some interest- 
 ing details last month. Fig. IS. PALCDIHA VIVH-AKA. 
 
54 STUDIES IN ANIMAL LIFE. 
 
 Scattered over the surface of the net and dead leaves 
 are little dabs of dirty -looking jelly some of them, 
 instead of the dirty hue, are almost blood-red. Ex- 
 perience makes me aware that these dirty dabs are 
 certainly Polypes the Hydra fusca of systematists. 
 I can't tell how it is I know them, nor how you may 
 know them again. The power of recognition must 
 be acquired by familiarity ; and it is because men 
 can't begin with familiarity, and can't recognize these 
 Polypes without it, that so few persons really ever 
 see them. But the familiarity may be acquired by a 
 very simple method. Make it a rule to pop every 
 unknown object into your wide-mouthed phial. In 
 the water it will probably at once reveal its nature : 
 if it be a Polype, it will expand its tentacles ; if not, 
 you can identify it at leisure on reaching home by 
 the aid of pictures and descriptions. See, as I drop 
 one of these into the water, it at once assumes the well- 
 known shape of the Polype. And now we will see 
 what these blood-red dabs may be ; in spite of their 
 unusual color, I can not help suspecting them to be 
 Polypes also. Give me the camel-hair brush. Gen- 
 tly the dab is removed, and transferred to the phial. 
 Shade of Trembley ! it is a Polype !* Is it possible 
 that this discovery leaves you imperturbable, even 
 
 * TREMBLEY, in his admirable work, Memoires pour servir a 
 Vkistoire dune genre de Polypes deau dome, 1744, furnished science 
 with the fullest and most accurate account of fresh-water Polypes ; 
 but it is a mistake to suppose that he was the original discoverer of 
 this genus : old LEUWENHOEK had been before him. 
 
STUDIES IN ANIMAL LIFE. 55 
 
 when I assure you it is of a species hitherto unde- 
 scribed in text-books ? Now don't be provokingly 
 indifferent ! rouse yourself to a little enthusiasm, 
 and prove that you have something of the natural- 
 ist in you by delighting in the detection of a new 
 species. "You didn't know that it was new?" 
 That explains your calmness. There must be a 
 basis of knowledge before wonder can be felt 
 wonder being, as Bacon says, " broken knowledge." 
 Learn, then, that hitherto only three species of 
 fresh-water Polypes have been described: Hydra 
 viridis, Hydra fusca, and Hydra grisea. We have 
 now a fourth to swell the list; we will christen it 
 Hydra rubra, and be as modest in our glory as we 
 can. If any one puts it to us whether we seriously 
 attach importance, to such trivialities as specific dis- 
 tinctions resting solely upon color or size, we can 
 look profound, you know, and repudiate the charge. 
 But this is a public and official attitude. In pri- 
 vate we can despise the distinctions established by 
 others, but keep a corner of favoritism for our own.* 
 I remember once showing a bottle containing 
 Polypes to a philosopher, who beheld them with 
 great calmness. They appeared to him as insignifi- 
 
 * The editors of the Annals of Natural History append a note to 
 the account I sent them of this new Polype, from which it appears 
 that Dr. Gray found this very species, and apparently in the. same 
 spot, nearly thirty years ago. But the latest work of authority, 
 VAN DER HOVEN'S Handbook of Zoology, only enumerates the three 
 species. 
 
56 STUDIES IN ANIMAL LIFE. 
 
 cant as so many stems of duckweed ; and, lest you 
 should be equally indifferent, I will at once inform 
 you that these creatures will interest you as much 
 as any that can be found in ponds, if you take the 
 trouble of studying them. They can be cut into 
 many pieces, and each piece will grow into a per- 
 fect Polype ; they may be pricked or irritated, and 
 the irritated spot will bud a young Polype, as a 
 plant buds; they may be turned inside out, and 
 their skin will become a stomach, their stomach a 
 skin. They have acute sensibility to light (toward 
 which they always move), and to the slightest touch; 
 yet not a trace of a nervous tissue is to be found in 
 them. They have powers of motion and locomo- 
 tion, yet their muscles are simply a network of 
 large contractile cells. If the water in which they 
 are kept be not very pure, they will be found in- 
 fested with parasites ; and quite recently I have no- 
 ticed an animal or vegetal parasite I know not 
 which forming an elegant sort of fringe to the 
 tentacles ; clusters of skittle-shaped bodies, too en- 
 tirely transparent for any structure whatever to tie 
 made out, in active agitation, like leaves fluttering 
 on a twig. Some day or other we may have occa- 
 sion to treat of the Polypes in detail, and to narrate 
 the amusing story of their discovery ; but what has 
 already been said will serve to sharpen your atten- 
 tion, and awaken some curiosity in them. 
 
 Again and again the net sweeps among the weed 
 or dredges the bottom of the pond, bringing up mud, 
 
STUDIES IN ANIMAL LIFE. 57 
 
 stones, sticks, with a fish, worms, mollusks, and tri- 
 tons. The fish we must secure, for it is a stickle- 
 back a pretty and interesting inhabitant of an 
 aquarium, on account of its nest-building propensi- 
 ties. We are surprised at a fish building a nest 
 and caring for its young like the tenderest of birds 
 (and there are two other fishes, the Goramy and the 
 Hassar, which have this instinct); but why not a 
 fish as well as a bird? The catfish swims about 
 in company with her young, like a proud hen with 
 her chickens, and the sunfish hovers for weeks over 
 her eggs, protecting them against danger. 
 
 The wind is so piercing, and my fingers are so 
 benumbed, I can scarcely hold the brush. More- 
 over, continual stooping over the net makes the 
 muscles ache unpleasantly, and suggests that each 
 cast shall be the final one. But somehow I have 
 made this resolution and broken it twenty times : 
 either the cast has been unsuccessful, and one is 
 provoked to try again, or it is so successful that, as 
 Tappetit vient en mangeant, one is seduced again. 
 Yery unintelligible this would be to the passers- 
 by, who generally cast contemptuous glances at us 
 when they find we are not fishing, but are only re- 
 moving nothings into a glass jar. One day an 
 Irish laborer stopped and asked me if I were fish- 
 ing for salmon. I quietly answered "Yes." He 
 drew near. I continued turning over the weed, oc- 
 casionally dropping an invisible thing into the wa- 
 ter. At last a large yellow-bellied Triton was 
 C2 
 
58 STUDIES IN ANIMAL LIFE. 
 
 dropped in. He begged to see it; and, seeing at 
 the same time how alive the water was with tiny 
 animals, became curious, and asked many questions. 
 I went on with my work ; his interest and curiosity 
 increased ; his questions multiplied ; he volunteered 
 assistance ; and remained beside me till I prepared 
 to go away, when he said seriously, "Och! then, 
 and it's a fine thing to be able to name all God's 
 creatures." Contempt had given place to rever- 
 ence ; and so it would be with others, could they 
 check the first rising of scorn at what they do not 
 understand, and patiently learn what even a road- 
 side pond has of Nature's wonders. 
 
STUDIES IN ANIMAL LIFE. 69 
 
 CHAPTER HI. 
 
 A garden Wall, and its Traces of past Life. Not a Breath per- 
 ishes. A Bit of dry Moss and its Inhabitants. The "Wheel- 
 bearers." Resuscitation of Rotifers: drowned into Life. 
 Current Belief that Animals can be revived after complete De- 
 siccation. Experiments contradicting the Belief. Spallanzani's 
 Testimony. Value of Biology as a Means of Culture. Classi- 
 fication of Animals : the five great Types. Criticism of Cu- 
 vier's Arrangement. 
 
 PLEASANT, both to eye and mind, is an old gar- 
 den wall, dark with age, gray with lichens, green 
 with mosses* of beautiful hues and fairy elegance of 
 form ; a wall shutting in some sequestered home, 
 far from "the din of murmurous cities vast;" a 
 home where, as we fondly, foolishly think, Life 
 must needs throb placidly,. and all its tragedies and 
 pettinesses be unknown. As we pass alongside this 
 wall, the sight of the overhanging branches sug- 
 gests an image of some charming nook; or our 
 thoughts wander about the wall itself, calling up 
 the years during which it has been warmed by the 
 sun, chilled by the night airs and the dews, and 
 dashed against by the wild winds of March, all of 
 which have made it quite another wall from what 
 it was when the trowel first settled its bricks. The 
 old wall has a past, a life, a story ; as Wordsworth 
 
60 STUDIES IN ANIMAL LIFE. 
 
 finely says of the mountain, it is " familiar with for- 
 gotten years." Not only are there obvious traces 
 of age in the crumbling mortar and the battered 
 brick, but there are traces, not obvious except to 
 the inner eye, left by every ray of light, every rain- 
 drop, every gust. Nothing perishes. In the won- 
 drous metamorphosis momently going on every 
 where in the universe, there is change, but no loss. 
 
 Lest you should imagine this to be poetry, and 
 not science, I will touch on the evidence that every 
 beam of light, or every breath of air which falls 
 upon an object, permanently affects it. In photog- 
 raphy we see the effect of light very strikingly ex- 
 hibited; but perhaps you wilt object that this proves 
 nothing more than that light acts upon an iodized 
 surface. Yet, in truth, light acts upon, and more or 
 less alters the structure of every object on which it 
 falls. Nor is this all. If a wafer be laid on a sur- 
 face of polished metal, which is then breathed upon, 
 and if, when the moisture of the breath has evapo- 
 rated, the wafer be shaken off, we shall find that the 
 whole polished surface is not as it was before, al- 
 though our senses can detect no difference ; for if 
 we breathe again upon it, the surface will be moist 
 every where except on the spot previously shelter- 
 ed by the wafer, which will now appear as a spec- 
 tral image on the surface. Again and again we 
 breathe, and the moisture evaporates, but still the 
 spectral wafer reappears. This experiment suc- 
 ceeds after a lapse of many months if the metal be 
 
STUDIES IN ANIMAL LIFE. 6i 
 
 carefully put aside where its surface can not be dis- 
 turbed. If a sheet of paper on which a key has 
 been laid be exposed for some minutes to the sun- 
 shine, and then instantaneously viewed in the dark, 
 the key being removed, a fading spectre of the key 
 will be visible. Let this paper be put aside for 
 many months where nothing can disturb it, and 
 then in darkness be laid on a plate of hot metal, 
 the spectre of the key will again appear. In the 
 case of bodies more highly phosphorescent than 
 paper, the spectres of many different objects which 
 may have been laid on in succession will, on warm- 
 ing, emerge in their proper order.* 
 
 This is equally true of our bodies and our minds. 
 We are involved in the universal metamorphosis. 
 Nothing leaves us wholly as it found us. Every 
 man we meet, every book we read, every picture 
 or landscape we see, every word or tone we hear, 
 mingles with our being and modifies it. There are 
 cases on record of ignorant women, in states of in- 
 sanity, uttering Greek and Hebrew phrases, which 
 in past years they had heard their masters utter, 
 without, of course, comprehending them. These 
 tones had long been forgotten ; the traces were so 
 faint that under ordinary conditions they were 'in- 
 visible ; but the traces were there, and in the in- 
 tense light of cerebral excitement they started into 
 prominence, just as the spectral image of the key 
 started into sight on the application of heat. It is 
 
 * DRAPER : Human Physiology, p. 288. 
 
62 STUDIES IN ANIMAL LIFE. 
 
 thus with all the influences to which we are sub- 
 jected. 
 
 If a garden wall can lead our vagabond thoughts 
 into such speculations as these, surely it may also 
 furnish us with matter for our Studies in Animal 
 Life. Those patches of moss must be colonies. 
 Suppose we examine them. I pull away a small 
 bit, which is so dry that the dust crumbles at a 
 touch ; this may be wrapped in a piece of paper 
 dirt and all and carried home. Get the micro- 
 scope ready, and now attend. 
 
 I moisten a fragment of this moss with distilled 
 water. Any water will do as well, but the use of 
 distilled water prevents your supposing that the 
 animals you are about to watch were brought in it, 
 and were not already in the moss. I now squeeze 
 the bit between my fingers, and a drop of the con- 
 tained water somewhat turbid with dirt falls on 
 the glass slide, which we may now put on the mi- 
 croscope stage. A rapid survey assures us that 
 there is no animal visible. The moss is squeezed 
 again, and this time little yellowish bodies of an 
 irregular oval are noticeable among the particles 
 of dust and moss. Watch one of these, and pres- 
 ently you will observe a slow bulging at one end, 
 and then a bulging at the other end. The oval 
 has elongated itself into a form not unlike that- 
 of a fat caterpillar, except that there is a tapering 
 at one end. Now a forked tail is visible ; this fixes 
 on to the glass, while the body swings to and fro. 
 
STUDIES IN ANIMAL LIFE. 
 
 Now the head is drawn in as if it were swallowed 
 and suddenly in its place are unfolded two broad 
 membranes, having each a circle of waving cilia. 
 The lifeless oval has become a living animal ! You 
 have assisted at a resuscitation, not from death by 
 drowning, but by drying: the animal has been 
 drowned into life ! The unfolded membranes, with 
 their cilia, have so much the appearance of wheels 
 that the name of " "Wheel-bearer" (Rotifera) or 
 " Wheel Animalcule" has been given to the animal. 
 
 Fig. 16. ROTTFEB VULGABIB. 
 
 A, with the wheels drawn in (at c). B, with the wheels expanded; 6, eye 
 ppots; e, jaw and teeth; /, alimentary canal; gr, embryo; A, embryo further 
 developed : ?', water- vascular system ; fc, vent. 
 
64 STUDIES IN ANIMAL LIFE. 
 
 The Eotifera (also, and more correctly, called 
 Rotatoria) form an interesting study. Let us glance 
 at their organization : 
 
 There are many different kinds of Kotifers, vary- 
 ing very materially in size and shape, the males, as 
 was stated in the last chapter, being more imper- 
 fectly organized than the females. They may be 
 seen either swimming rapidly through the water 
 by means of the vibratile cilia called " wheels," be- 
 cause the optical effect is very much that of a 
 toothed wheel, or crawling along the side of the 
 glass, fastening to it by the head, and then curving 
 the body till the tail is brought up to the spot, 
 which is then fastened on by the tail, and the head 
 is set free. They may also be seen fastened to a 
 weed, or the glass, by the tail, the body waving to 
 and fro, or thrusting itself straight out, and setting 
 the wheels in active motion. In this attitude the 
 aspect of the jaws is very striking. Leuwenhoek 
 mistook it for the pulsation of a heart, which its in- 
 cessant rhythm much resembles. The tail and the 
 upper part of the body have a singular power of 
 being drawn out or drawn in, like the tube of a 
 telescope. There is sometimes a shell or carapace, 
 but often the body is covered only with a smooth 
 firm skin, which, however, presents decided indica- 
 tions of being segmented. 
 
 The first person who described these Eotifers was 
 the excellent old Leuwenhoek,* and his animals 
 
 * LEUWENHOEK: Select Works, ii., p. 210. His figures, how- 
 ever, are very incorrect. 
 
STUDIES IN ANIMAL LIFE. t>5 
 
 were got from the gutter of a house-top. Since 
 then they have been minutely studied, and have 
 been shown to" be, not Infusoria, as Ehrenberg im- 
 agined, but Crustacea.* Your attention is request- 
 ed to the one point which has most contributed to 
 the celebrity of these creatures their power of re- 
 suscitation. Leuwenhoek described what you 
 have just witnessed, namely the slow resuscitation 
 of the animal (which seemed as dry as dust, and 
 might have been blown about like any particle of 
 dust) directly a little moisture was brought to it. 
 Spallanzani startled the world with the announce- 
 ment that this process of drying and moistening 
 of killing and reviving could be repeated fifteen 
 times in s accession; so that the Kotifer, whose nat- 
 ural term of life is about eighteen days, might, it 
 was said, be dried and kept for years, and at any 
 time revived by moisture. That which seems now 
 no better than a grain of dust will suddenly awaken 
 to the energetic life of a complex organism, and 
 may again be made as dust by the evaporation of 
 the water. 
 
 This is very marvelous; so marvelous that a 
 mind trained in the cultivated caution of science 
 will demand the evidence on which it is based. 
 Two months ago I should have dismissed the doubt 
 with the assurance that the evidence was ample and 
 
 * See LEYDIG : Ueber den Bau und die systematische Stellung 
 der Rdderthiere, in SIEBOLD und KOLLIKER'S Zeitschrift, vi., and 
 Ueber Hydatina Senta, in MULLER'S Arr.hiv, 1857. 
 
66 STUDIES IN ANIMAL LIFE. 
 
 rigorous, and the fact indisputable; for not only 
 had the fact been confirmed by the united experi- 
 ence of several investigators, it had stood the test 
 of very severe experiment. Thus, in 1842, M. Do- 
 yere published experiments which seemed to place 
 it beyond skepticism. Under the air-pump he set 
 some moss, together with vessels containing sul- 
 phuric acid, which would absorb every trace of 
 moisture. After leaving the moss thus for a week, 
 he removed it into an oven, the temperature of which 
 was raised to 300 Fahrenheit. Yet even this treat- 
 ment did not prevent the animals from resuscitating 
 when water was added. 
 
 In presence of testimony like this, doubt will seem 
 next to impossible. Nevertheless, my own experi- 
 ments leave me no choice but to doubt. Not hav- 
 ing witnessed M. Doyere's experiment, I ani not 
 prepared to say wherein its fallacy lies ; but that 
 there is a fallacy seems to me capable of decisive 
 proof. In M. Pouchet's recent work* I first read a 
 distinct denial of the pretended resuscitation of the 
 Eotifers ; this denial was the more startling to me, 
 because I had myself often witnessed the reawaken- 
 ing of these dried animals. Nevertheless, whenev- 
 er a doubt is fairly started, we have not done jus- 
 tice to it until we have brought it to the test of ex- 
 periment; accordingly, I tested this, and quickly 
 came upon what seems to me the source of the gen- 
 
 * POUCHET : Heterogenie, ou Traite de la Generation Spontanee, 
 1859, p. 453. 
 
STUDIES IN ANIMAL LIFE. 67 
 
 eral misconception. Day after day experiments 
 were repeated, varied, and controlled, and with re- 
 sults so unvarying that hesitation vanished ; and as 
 some of these experiments are of extreme simplici- 
 ty, you may verify what I say with little trouble. 
 Squeeze a drop from the moss, taking care that 
 there is scarcely any dirt in it ; and, having ascer- 
 tained that it contains Eotifers or Tardigrades,* 
 alive and moving, place the glass slide under a bell- 
 glass, to shield it from currents of air, and there al- 
 low the water to evaporate slowly, but completely, 
 by means of chloride of calcium or sulphuric acid 
 placed under the bell-glass; or, what is still sim- 
 pler, place a slide with the live animals on the man- 
 telpiece when a fire is burning in the grate. If on 
 the day following you examine this perfectly dry 
 glass, you will see the contracted bodies of the Eo- 
 tifers, presenting the aspect of yellowish oval bodies; 
 but attempt to resuscitate them by the addition of 
 a little fresh water, and you will find that they do 
 not revive, as they revived when dried in the moss ; 
 they sometimes swell a little, and elongate them- 
 selves, and you imagine this is a commencement of 
 resuscitation; but continue watching for two or 
 -three days, and you will find it goes no further. 
 
 * The Tardigrade, or microscopic Sloth, belongs to the order of 
 Arachnida, and is occasionally found in moss, stagnant ponds, etc. 
 I have only met with four specimens in all my investigations, and 
 they were all found in moss. SPALLANZANI described and figured 
 it (very badly), and M. DOYEEE has given a fuller description in 
 the Annaks des Sciences, 2d series, vols. xiv., xvii., and xviii. 
 
68 STUDIES IN ANIMAL LIFE. 
 
 Never do these oval bodies become active crawling 
 Eotifers; never do they expand their wheels, and 
 set the oesophagus at work. No ; the Kotifer once 
 dried is dead, and dead forever. 
 
 But if, like a cautious experimenter, you vary 
 and control the experiment, and beside the glass 
 slide place a watch-glass containing Eotifers with 
 dirt or moss, you will find that the addition of wa- 
 ter to the contents of the watch-glass will often (not 
 always) revive the animals. What you can not ef- 
 fect on a glass slide without dirt, or with very little, 
 you easily effect in a watch-glass with dirt or moss ; 
 and if you give due attention you will find that in 
 each case the result depends upon the quantity of 
 the dirt. And this leads to a clear understanding 
 of the whole mystery ; this reconciles the conflict- 
 ing statements. The reason why Eotifers ever re- 
 vive is because they have not been dried they 
 have not lost by evaporation that small quantity 
 of water which forms an integral constituent of their 
 tissues; and it is the presence of dirt or moss which 
 prevents this complete evaporation. No one, I sup- 
 pose, believes that the Eotifer actually revives after 
 once being dead. If it has a power of remaining in 
 a state of suspended animation, like that of a frozen 
 frog, it can do so only on the condition that its or- 
 ganism is not destroyed; and destroyed it would 
 be if the water were removed from its tissues ; for, 
 strange as it may seem, water is not an accessory, 
 but a constituent element of every tissue; and this 
 
STUDIES IN ANIMAL LIFE. 69 
 
 can not be replaced mechanically it can only be 
 replaced by vital processes. Every one who has 
 made microscopic preparations must be aware that 
 when once a tissue is desiccated, it is spoiled; it 
 will not recover its form and properties on the ap- 
 plication of water, because the water was not orig- 
 inally worked into the web by a mere process of 
 imbibition like water in a sponge but by a molec- 
 ular process of assimilation, like albumen in a mus- 
 cle. Therefore I say that desiccation is necessarily 
 .death, and the Eotifer which revives can not have 
 been desiccated. This being granted, we have only 
 to ask, "What prevents the Eotifer from becoming 
 completely dried ? Experiment shows that it is the 
 presence of dirt or moss which does this. The 
 whole marvel of the Eotifer's resuscitation, there- 
 fore, amounts to this : that if the water in which it 
 lives be evaporated, the animal passes into a state 
 of suspended animation, and remains so as long as 
 its own water is protected from evaporation. 
 
 I am aware that this is not easily to be reconciled 
 with M. Doyere's experiment, since the application 
 of a temperature so high as 300 Fahrenheit (nearly 
 a hundred degrees above boiling water) must, one 
 would imagine, have completely desiccated the ani- 
 mals, in spite of any amount of protecting dirt. It 
 is possible that M. Doyere may have mistaken that 
 previously-noticed swelling up of the bodies, on the 
 application of water, for a return to vital activity. 
 Tf not, I am at a loss to explain the contradiction ; 
 
70 STUDIES IN ANIMAL LIFE. 
 
 for certainly in my experience a much more mod- 
 erate desiccation namely, that obtained by simple 
 evaporation over a mantelpiece or under a large 
 bell-glass always destroyed the animals if little or 
 no dirt were present. 
 
 The subject has recently been brought before the 
 French Academy of Sciences by M. Davaine, whose 
 experiments* lead him to the conclusion that those 
 Rotifers which habitually live in ponds will not re- 
 vive after desiccation, whereas those which live in 
 moss always do so. I believe the explanation to be 
 this : the Rotifers living in ponds are dried without 
 any protecting dirt or moss, and that is the reason 
 they do not revive. 
 
 After having satisfied myself on this point, I did 
 what perhaps would have saved me some trouble 
 if thought of before. I took down Spallanzani, and 
 read his account of his celebrated experiments. To 
 my surprise and satisfaction, it appeared that he 
 had accurately observed the same facts, but curious- 
 ly missed their real significance. Nothing can be 
 plainer than the following passage : " But there is 
 one condition indispensable to the resurrection of 
 wheel-animals : it is absolutely necessary that there 
 should be a certain quantity of sand; without it 
 they will not revive. One day I had two wheel- 
 animals traversing a drop of water about to evapo- 
 rate which contained very little sand. Three quar- 
 ters of an hour after evaporation they were dry and 
 
 * DAVAINE in Annales des Sciences Naturelles, 1858, x., p. 335. 
 
STUDIES IN ANIMAL LIFE. 71 
 
 motionless. I moistened them with water to revive 
 them, but in vain, notwithstanding that they were 
 immersed in water many hours. Their members 
 swelled to thrice the original size, but they remain- 
 ed motionless. To ascertain whether the fact was 
 accidental, I spread a portion of sand, containing 
 animals, on a glass slide, and waited until it became 
 dry in order to wet it anew. The sand was care- 
 lessly scattered on the glass, so as to be a thin cov- 
 ering on some parts, and on others in a very small 
 quantity : here the animals did not revive ; but all 
 that were in those parts with abundance of sand re- 
 vived."* He further says that if sand be spread 
 out in considerable quantities in some places, much 
 less in others, and very little in the rest, on moist- 
 ening it the revived animals will be numerous in 
 the first, less numerous in the second, and none at 
 all in the third. 
 
 It is not a little remarkable that observations so 
 precise as these should have for many years passed 
 unregarded, and not led to the true explanation of 
 the mystery. Perhaps an inherent love of the mar- 
 velous made men greedily accept the idea of resus- 
 citation, and indisposed them to attempt an expla- 
 nation of it. Spallanzani's own attempt is certainly 
 not felicitous. He supposes that the dust prevents 
 the lacerating influence of the air from irritating and 
 injuring the animals. And this explanation is ac- 
 cepted by his translator. 
 
 * SPALLAKZAKI: Tracts on the Natural History of Animals and 
 Vegetable*: translated by Dalyell, ii., p. 129. 
 
72 STUDIES IN ANIMAL LIFE. 
 
 [Since the foregoing remarks were in type, M. 
 Gavarret has published (Annales des Sciences Natu- 
 relles, 1859, xi., p. 315) the account of his experi- 
 ments on Eotifers and Tardigrades, in which he 
 found that after subjecting the moss to a desiccation 
 the most complete according to our present means, 
 the animals revived after twenty -four hours' immer- 
 sion of the moss in water. This result seems flatly 
 to contradict the result I arrived at, but only seems 
 to contradict it, for in my experiments the animals, 
 not the moss, were subjected to desiccation. Nev- 
 ertheless, I confess that my confidence was shaken 
 by experiments so precise, and performed by so dis- 
 tinguished an investigator, and I once more resumed 
 the experiments, feeling persuaded that the detec- 
 tion of the fallacy, wherever it might be, would be 
 well worth the trouble. The results of these con- 
 trolling experiments are all I can find room for 
 here : Whenever the animals were completely separated 
 from the dirt, they perished ; in two cases there was 
 a very little dirt a mere film, so to speak in the 
 watch-glass and glass cell, and this, slight as it was, 
 sufficed to protect two out of eight, and three out 
 of ten Eotifers, which revived on the second day ; 
 the others did not revive even on the third day aft- 
 er their immersion. In one instance, a thin cover- 
 ing-glass was placed over the water on the slide, 
 and the evaporation of the water seemed complete, 
 yet this glass cover sufficed to protect a Eotifer, 
 which revived in three hours. 
 
STUDIES IN ANIMAL LIFE. 73 
 
 If we compare these results with those obtained 
 by M. Davaine, we can scarcely avoid the conclusion 
 that it is only when the desiccation of the Eotifers 
 is prevented by the presence of a small quantity of 
 moss or of dirt between the particles of which they 
 find shelter that they revive on the application of 
 water. And even in the severe experiments of M. 
 Doyere and M. Gavarret, some of the animals must 
 have been thus protected ; and I call particular at- 
 tention to the fact that, although some animals re- 
 vived, others always perished. But if the organiza- 
 tion of the Kotifer or Tardigrade is such that it can 
 withstand desiccation if it only needs the fresh ap- 
 plication of moisture to restore its activity all, or 
 almost all the animals experimented on ought to 
 revive ; and the fact that only some revive leads us 
 to suspect that these have not been desiccated a 
 suspicion which is warranted by direct experiments. 
 I believe, then, that the discrepancy amounts to 
 this : investigators who have desiccated the moss 
 containing animals find some of the animals revive 
 on the application of moisture, but those who desic- 
 cate the animals themselves will find no instances 
 of revival.] 
 
 The time spent on these Eotifers will not have 
 been misspent if it has taught us the necessity of 
 caution in all experimental inquiries. Although 
 experiment is valuable nay, indispensable as a 
 means of interrogating Nature, it is constantly lia- 
 ble to mislead us into the idea that we have rightly 
 D 
 
74 STUDIES IN ANIMAL LIFE. 
 
 interrogated and rightly interpreted the replies; 
 and this danger arises from the complexity of the 
 cases with which we are dealing, and our proneness 
 to overlook or disregard some seemingly trifling 
 condition a trifle which may turn out of the ut- 
 most importance. The one reason why the study 
 of science is valuable as a means of culture, over 
 and above its own immediate objects, is that in it 
 the mind learns to submit to realities instead of 
 thrusting its figments in the place of realities en- 
 deavors to ascertain accurately what the order of 
 Nature w, and not what it ought to be or might be. 
 The one reason why, of all sciences, Biology is pre- 
 eminent as a means of culture, is, that, owing to the 
 great complexity of all the cases it investigates, it 
 familiarizes the mind with the necessity of attend- 
 ing to all the conditions, and it thus keeps the mind 
 alert. It cultivates caution, which, considering the 
 tendency there is in men to " anticipate Nature," is 
 a mental tonic of inestimable worth. I am far from 
 asserting that biologists are more accurate reasoners 
 than other men ; indeed, the mass of crude hypoth- 
 esis which passes unchallenged by them is against 
 such an idea. But, whether its advantage be used 
 or neglected, the truth nevertheless is, that Biology, 
 from the complexity of its problems, and the ne- 
 cessity of incessant verification of its details, offers 
 greater advantages for culture than any other branch 
 of science. 
 
 I have once or twice mentioned the words Mol- 
 
s^pTupJ^ 
 
 v v or TfeE if r 
 
 OF TfcE 
 STUDIES IN ANIMAL 
 
 lusk and Crustacean, to which the 
 with the language of Natural History wirl have at 
 tached but vague ideas ; and although I wanted to 
 explain these, and convey a distinct conception of 
 the general facts of classification, it would have 
 been too great an interruption. So I will here 
 make an opportunity, and finish the chapter with 
 an indication of the five types, or plans of struct- 
 ure, under one of which every animal is classed. 
 Without being versed in science, you discern at 
 once whether the book before you is mathematical, 
 physical, chemical, botanical, or physiological. In 
 like manner, without being versed in Natural His- 
 tory, you ought to know whether the animal be- 
 fore you belongs to the Yertebrata, Mollusca, Artic- 
 ulata, Kadiata, or Protozoa. 
 
 A glance at the contents of our glass vases will 
 yield us samples of each of these five divisions of 
 the animal kingdom. We begin with this Triton 
 (Fig. 17). It is a representative of the VERTEBRATE 
 division or sub-kingdom. You have merely to re- 
 member that it possesses a backbone and an inter- 
 nal skeleton, and you will at once recognize the 
 cardinal character which makes this Triton range 
 under the same general head as men, elephants, 
 whales, birds, reptiles, or fishes. All these, in spite 
 of their manifold differences, have this one charac- 
 ter in common they are all backboned ; they have 
 all an internal skeleton; they are all formed ac- 
 cording to one general tvpe. In all vertebrate ani- 
 
76 
 
 STUDIES IN ANIMAL LIFE. 
 
 Fig. 17. MALE TBITON, OR WATEB-NEWT. 
 
 mals the skeleton is found to be identical in plan. 
 Every bone in the body of a triton has its corre- 
 sponding bone in the body of a man or of a mouse ; 
 and every bone preserves the same connection with 
 other bones, no matter how unlike may be the va- 
 rious limbs in which we detect its presence. Thus, 
 widely as the arm of a man differs from the fin of 
 a whale, or the wing of a bird, or the wing of a bat, 
 or the leg of a horse, the same number of bones, 
 and the same connections of the bones, are found in 
 each. A fin is one modified form of the typical 
 limb ; an arm is another ; a wing another. That 
 which is true of the limbs is also true of all the 
 other organs; and it is on this ground that we 
 speak of the vertebrate type. From fish to man 
 
STUDIES IN ANIMAL LIFE. 77 
 
 one common plan of structure prevails, and the 
 presence of a backbone is the index by which to 
 recognize this plan. 
 
 The Triton has been wriggling grotesquely in 
 our grasp while we have made him our text, and, 
 now he is restored to his vase, plunges to the bot- 
 tom with great satisfaction at his escape. This wa- 
 ter-snail, crawling slowly up the side of the vase, 
 and cleaning it of the green growth of microscopic 
 plants, which he devours, shall be our representa- 
 tive of the second great division the MOLLUSCA. 
 I can not suggest any obvious character so distinct- 
 ive as a backbone by which the word mollusk may 
 at once call up an idea of the type which prevails 
 in the group. It won't do to say " shellfish," be- 
 cause many mollusks have no shells, and many ani- 
 mals which have shells are not mollusks. The 
 name was originally bestowed on account of the 
 softness of the animals. But they are not softer 
 than worms, and much less so than jellyfish. You 
 may know that snails and slugs, oysters and cuttle- 
 fish, are mollusks ; but if you want some one char- 
 acter by which the type may be remembered, you 
 must fix on the imperfect symmetry of the mol- 
 lusk's organs. I say imperfect symmetry, because it 
 is an error, though a common one, to speak of the 
 mollusk's body not being bilateral that is to say, of 
 its not being composed of two symmetrical halves. 
 A vertebrate animal may be divided lengthwise, 
 and each half will closely resemble the other ; the 
 
78 STUDIES IN ANIMAL LIFE. 
 
 backbone forms, as it were, an axis, on either side 
 of which the organs are disposed ; but the mollusk 
 is said to have no such axis, no such symmetry. I 
 admit the absence of an axis, but I deny the total 
 absence of symmetry. Many of its organs are as 
 symmetrical as those of a vertebrate animal i. e., 
 the eyes, the feelers, the jaws and the gills in Cut- 
 tlefish, Eolids, and Pteropods ; while, on the other 
 hand, several organs in the vertebrate animal are as 
 asymmetrical as any of those in the mollusk i. e., 
 the liver, spleen, pancreas, stomach, and intestines.* 
 As regards bilateral structure, therefore, it is only 
 a question of degree. The vertebrate animal is not 
 entirely symmetrical, nor is the mollusk entirely 
 unsymmetrical. But there is a characteristic dis- 
 position of the nervous system peculiar to mol- 
 lusks : it neither forms an axis for the body, as it 
 does in the Yertebrata and Articulata, nor a centre, 
 as it does in the Eadiata, but is altogether irregular 
 and unsymmetrical. This will be intelligible from 
 the following diagram of the nervous systems of a 
 mollusk and an insect, with which that of a starfish 
 may be compared (Fig. 18). Here you perceive 
 how the nervous centres and the nerves which 
 
 * In some cases of monstrosity these organs are transposed, the 
 liver being on the left, and the pancreas on the right side. It was 
 in allusion to a case of this kind, then occupying the attention of 
 Paris, that MOLIERE made his Mededn malgre Lui describe the 
 heart as on the right side, the liver on the left ; on the mistake be- 
 ing noticed, he replies, " Oui, autrefois ; mais nous avons change 
 tout cela." 
 
STUDIES IN ANIMAL LIFE. 
 
 79 
 
 Fig. 18. NERVOUS SYSTEM OP SEA-HABE (A) and CENTIPEDE (B). 
 
 Fig. 19. NERVOUS SYSTEM OF STARFISH. 
 
80 STUDIES IN ANIMAL LIFE. 
 
 issue from them are irregularly disposed in the 
 mollusks, and symmetrically in the insect. 
 
 But the recognition of a mollusk will be easier 
 when you have learned to distinguish it from one 
 of the AETICULATA, forming the third great divi- 
 sion the third animal type. Of these, our vases 
 present numerous representatives prawns, beetles, 
 water-spiders, insect-larvae, entomostraca, and worms. 
 There is a very obvious character by which these 
 may be recognized : they have all bodies composed 
 of numerous segments, and their limbs are jointed, 
 and they have mostly an external skeleton from 
 which their limbs are developed. Sometimes the 
 segments of their bodies are numerous, as in the 
 centipede, lobster, etc. ; sometimes several segments 
 are fused together, as in the crab ; and sometimes, 
 as in worms, they are indicated by slight markings 
 or depressions of the skin, which give the appear- 
 ance of little rings, and hence the worms have been 
 named Annelida, or Annulata, or Annulosa. In these 
 last-named cases the segmental nature of the type is 
 detected in the fact that the worms grow, segment 
 by segment ; and also by the fact that- in most of 
 them each segment has its own nerves, heart, stom- 
 ach, etc. each segment is, in fact, a zooid.* 
 
 Just as we recognize a vertebrate by the presence 
 of a backbone and internal skeleton, we recognize 
 an articulate by its jointed body and external skele- 
 ton. In both, the nervous system forms the axis 
 
 * The term zooid was explained in our last chapter. 
 
STUDIES IN ANIMAL LIFE. 81 
 
 of the body. The Mollusk, on the contrary, has no 
 skeleton, internal or external,* and its nervous sys- 
 tem does not form an axis. As a rule, both verte- 
 brates and articulates have limbs, although there 
 are exceptions in serpents, fishes, and worms. The 
 Mollusks have no limbs. Backboned, jointed, and 
 non-jointed, therefore, are the three leading charac- 
 teristics of the three types. 
 
 Let us now glance at the fourth division the 
 EADIATA, so called because of the disposition of the 
 organs round a centre, which is the mouth. Our 
 fresh- water vases afford us only one representative 
 of this type the Hydra, or fresh-water Polype, 
 whose capture was recorded in the last chapter. Is 
 it not strange that while all the Kadiata are aquatic, 
 not a single terrestrial representative having been 
 discovered, only one should be found in fresh wa- 
 ter? Think of the richness of the seas, with their 
 hosts of Polypes, Actiniae, Jellyfish, Starfishes, Sea- 
 urchins, Sea-pens (Pennatulce), Lily -stars (Comatu- 
 Ice), and Sea-cucumbers (Rolothurice), and then com- 
 pare the poverty of rivers, lakes, and ponds, re- 
 duced to their single representative, the Hydra. 
 The radiate structure may best be exhibited by the 
 diagram of the nervous system of the Starfishf on 
 page 79. 
 
 * In the cuttlefish there is the commencement of an internal 
 skeleton in the cartilage-plates protecting the brain. 
 
 + It is right to add that there are serious doubts entertained re- 
 specting the claim of a starfish to the possession of a nervous sys- 
 
 D2 
 
82 STUDIES IN ANIMAL LIFE. 
 
 Cuvier, to whom we owe this classification of the 
 animal kingdom into four great divisions, would 
 have been the first to recognize the chaotic con- 
 dition in which he left this last division, and would 
 have acquiesced in the separation of the PROTOZOA, 
 which has since been made. This fifth division in- 
 cludes many of the microscopic animals known as 
 Infusoria, and receives its name from the idea that 
 these simplest of all animals represent, as it were, 
 the beginnings of life.* 
 
 But Cuvier's arrangement is open to a more se- 
 rious objection. The state of science in his day 
 excused the imperfection of classing the Infusoria 
 and parasites under the Eadiata ; but it was owing, I 
 conceive, to an unphilosophical view of morphology 
 that he placed the mollusks next to the Yertebrata, 
 instead of placing the Articulata in that position. 
 He was secretly determined by the desire to show 
 that there are four very distinct types, or plans of 
 structure, which can not by any transitions be 
 brought under one law of development. Lamarck 
 and Geoffroy St. Hilaire maintained the idea of uni- 
 ty of composition throughout the animal kingdom : 
 in other words, that all the varieties of animal forms 
 were produced by successive modifications ; and 
 several of the German naturalists maintained that 
 the vertebrata in their embryonic stages passed 
 
 tern at all ; but the radiate structure is represented in the diagram, 
 as it also is, very clearly, in a Sea-anemone. 
 
 * Protozoa, from proton, first, and zoon, animal. 
 
STUDIES IN ANIMAL LIFE. S3 
 
 through, forms which were permanent in the lower 
 animals. This idea Cuvier always opposed. He 
 held that the four types were altogether distinct; 
 and by his arrangement of them, their distinctness 
 certainly appears much greater than would be the 
 case on another arrangement. But, without dis- 
 cussing this question here, it is enough to point out 
 the fact of the enormous superiority in intelligence, 
 in sociality, and in complexity of animal functions 
 which insects and spiders exhibit when compared 
 with the highest of the mollusks, to justify the re- 
 moval of the mollusca, and the elevation of the ar- 
 ticulata to the second place in the animal hierarchy. 
 Nor is this all. If we divide animals into four 
 groups, these four naturally dispose themselves into 
 two larger groups: the first of these, comprising 
 Vertebrata and Articulata, is characterized by a 
 nervous axis and a skeleton ; the second, comprising 
 Mollusca and Eadiata, is characterized by the ab- 
 sence of both nervous axis and skeleton. It is ob- 
 vious that a bee much more closely resembles a 
 bird than any mollusk resembles any vertebrate. 
 If there are many and important differences be- 
 tween the vertebrate and articulate types, there are 
 also many and important resemblances ; if the nerv- 
 ous axis is above the viscera, and forms the dorsal 
 line of the vertebrate, whereas it is underneath the 
 viscera, and forms the ventral line in the articulate, 
 it is, nevertheless, in both, the axis of the body, and 
 in both it sends off nerves to supply symmetrical 
 
84 STUDIES IN ANIMAL LIFE. 
 
 limbs ; in both it has similar functions. And while 
 the articulata thus approach in structure the verte- 
 brate type, the mollusca are not only removed from 
 that type by many diversities, but a number of them 
 have such affinities with the Eadiate type that it is 
 only in quite recent days that the whole class of 
 Polyzoa (or Bryozoa, as they are also called) has 
 been removed from the Eadiata, and ranged under 
 the Mollusca. 
 
 To quit this topic, and recur once more to the 
 five divisions, we have only the broad outlines of 
 the picture in Yertebrata, Mollusca, Articulata, Ea- 
 diata, and Protozoa ; but this is a good beginning, 
 and we can now proceed to the further subdivisions. 
 Each of these five sub-kingdoms is divided into 
 classes; these, again, into orders; these into fami- 
 lies; these into genera; these into species; and 
 these, finally, into varieties. Thus, suppose a dwarf 
 terrier is presented to us with a request that we 
 should indicate its various titles in the scheme of 
 classification : we begin by calling it a vertebrate ; 
 we proceed to assign its class as the mammalian ; 
 its order is obviously that of the carnivora ; its 
 family is that of the fox, wolf, jackal, etc., named 
 Canidce ; its genus is, of course, that of Canis ; its 
 species, terrier; its variety, dwarf terrier. Inas- 
 much as all these denominations are the expres- 
 sions of scientific research, and not at all arbitrary 
 or fanciful, they imply an immense amount of labor 
 and sagacity in their establishment ; and when we 
 
{STUDIES IN ANIMAL LIFE. 85 
 
 remember that naturalists have thus classed upward 
 of half a million of distinct species, it becomes an 
 interesting inquiry, What has been -the guiding 
 principle of this successful labor? on what basis is 
 so large a superstructure raised ? This question we 
 shall answer in the next chapter. 
 
STUDIES IN ANIMAL LIFE. 
 
 CHAPTER IV. 
 
 An extinct Animal recognized by its Tooth : how came this to be 
 possible ? The Task of Classification. Artificial and natural 
 Methods. Linnaeus, and his Baptism of the Animal Kingdom: 
 his Scheme of Classification. What is there underlying all 
 true Classification? The chief Groups. What is a Species? 
 Restatement of the Question respecting the Fixity or Variability 
 of Species. The two Hypotheses. Illustration drawn from the 
 Romance Languages. Caution to Disputants. 
 
 I WAS one day talking with Professor Owen in the 
 Hunterian Museum, when a gentleman approached 
 with a request to be informed respecting the nature 
 of a curious fossil which had been dug up by one 
 of his workmen. As he drew the fossil from a 
 small bag, and was about to hand it for examina- 
 tion, Owen quietly remarked, " That is the third 
 molar of the under jaw of an extinct species of rhi- 
 noceros." The astonishment of the gentleman at 
 this precise, and confident description of the fossil, 
 before even it had quitted his hands, was doubtless 
 very great. I know that mine was, until the reflec- 
 tion occurred that if some one, little acquainted with 
 editions, had drawn a volume from his pocket, de- 
 claring he had found it in an old chest, any biblio- 
 phile would have been able to say at a glance, 
 "That is an Elzevir;" or, "That is one of the 
 Tauchnitz classics, stereotyped at Leipzig." Owen 
 is as familiar with the aspect of the teeth of ani- 
 
STUDIES IN ANIMAL LIFE. 87 
 
 raals, living and extinct, as a student is with the as- 
 pect of editions. Yet, before that knowledge could 
 have been acquired, before he could say thus confi- 
 dently that the tooth belonged to an extinct species 
 of rhinoceros, the united labors of thousands of dili- 
 gent inquirers must have been directed to the clas- 
 sification of animals. How could he know that the 
 rhinoceros was of that particular species rather than 
 another ? and what is meant by species ? To trace 
 the history of this confidence would be to tell the 
 long story of zoological investigation ; a story too 
 long for narration here, though we may pause a 
 while to consider its difficulties. 
 
 To make a classical catalogue of the books in the 
 British Museum would be a gigantic task ; but 
 imagine what that task would be if all the title- 
 pages and other external indications were destroy- 
 ed ! The first attempts would necessarily be of a 
 rough approximative kind, merely endeavoring to 
 make a sort of provisional order amid the chaos, 
 after which succeeding labors might introduce bet- 
 ter and better arrangements. The books might first 
 be grouped according to size ; but, having got them 
 together, it would soon be discovered that size was 
 no indication of their contents : quarto poems and 
 duodecimo histories, octavo grammars and folio 
 dictionaries, would immediately give warning that 
 some other arrangement was needed. Nor would 
 it be better to separate the books according to the 
 languages in which they were written. The pres- 
 
88 STUDIO IN ANIMAL LIFE. 
 
 ence or absence of " illustrations" would furnish no 
 better guide, while the bindings would soon be 
 found to follow no rule. Indeed, one by one, all 
 the external characters would prove unsatisfactory, 
 and the laborers would finally have to decide upon 
 some internal characters. Having read enough of 
 each book to ascertain whether it was poetry or 
 prose and, if poetry, whether dramatic, epic, lyric, 
 or satiric; and if prose, whether history, philoso- 
 phy, theology, philology, science, fiction, or essay 
 a rough classification could be made ; but even then 
 there would be many difficulties, such as where to 
 place a work on the philosophy of history or the 
 history of science or theology under the guise of 
 science or essays on very different subjects, while 
 some works would defy classification. 
 
 Gigantic as this labor would be, it would be tri- 
 fling compared with the labor of classifying all the 
 animals now living (not to mention extinct species), 
 so that the place of any one might be securely and 
 rapidly determined ; yet the persistent zeal and sa- 
 gacity of zoologists have done for the animal king- 
 dom what has not yet been done for the library of 
 the Museum, although the titles of the books are 
 not absent. It has been done by patient reading of 
 the contents by anatomical investigation of the in- 
 ternal structure of animals. Except on a basis of 
 comparative anatomy, there could have been no 
 better a classification of animals than a classification 
 of books according to size, language, binding, etc. 
 
STUDIES IN ANIMAL LIFE. 89 
 
 An unscientific Pliny might group animals accord- 
 ing to their habitat; but when it was known that 
 whales, though living in the water and swimming 
 like fishes, were in reality constructed like air- 
 breathing quadrupeds when it was known that 
 animals differing so widely as bees, birds, bats, and 
 flying squirrels, or as otters, seals, and cuttlefish, 
 lived together in the same element, it became ob- 
 vious that such a principle of arrangement could 
 lead to no practical result. Nor would it suffice to 
 class animals according to their modes of feeding, 
 since in all classes there are samples of each mode. 
 Equally unsatisfactory would be external form 
 the seal and the whale resembling fishes, the worm 
 resembling the eel, and the eel the serpent. 
 
 Two things were necessary : first, that the struc- 
 ture of various animals should be minutely studied 
 and described which is equivalent to reading the 
 books to be classified ; and, secondly, that some ar- 
 tificial method should be devised of so arranging the 
 immense mass of details as to enable them to be re- 
 membered, and also to enable fresh discoveries readi- 
 ly to find a place in the system. We may be per- 
 fectly familiar with the contents of a book, yet 
 wholly at a loss where to place it. If we have to 
 catalogue Hegel's Philosophy of History, for exam- 
 ple, it becomes a difficult question whether to place 
 it under the rubric of philosophy, or under that of 
 history. To decide this point, we must have some 
 system of classification. 
 
90 STUDIES IN ANIMAL LIFE. 
 
 In the attempts to construct a system, naturalists 
 are commonly said to have followed two methods, 
 the artificial and the natural. The artificial method 
 seizes some one prominent characteristic, and groups 
 all the individuals together which agree in this one 
 respect. In Botany the artificial method classes 
 plants according to the organs of reproduction ; but 
 this has been found so very imperfect that it has 
 been abandoned, and the natural method has been 
 substituted, according to which the whole structure 
 of the plant determines its place. If flying were 
 taken as the artificial basis for the grouping of some 
 animals, we should find insects and birds, bats and 
 flying squirrels grouped together; but the natural 
 method, taking into consideration not one character, 
 but all the essential characters, finds that insects, 
 birds, and bats differ profoundly in their organiza- 
 tion : the insect has wings, but its wings are not 
 formed like those of the bird, nor are those of the 
 bird formed like those of the bat. The insect does 
 not breathe by lungs, like the bird and the bat ; it 
 has no internal skeleton, like the bird and the bat ; 
 and the bird, although it has many points in com- 
 mon with the bat, does not, like it, suckle its young; 
 and thus we may run over the characters of each 
 organization, and find that the three animals belong 
 to widely different groups. 
 
 It is to Linnaeus that we are indebted for the 
 most ingenious and comprehensive of the many 
 schemes invented for the cataloguing of animal 
 
STUDIES IN ANIMAL LIFE. 91 
 
 forms, and modern attempts at classification are 
 only improvements on the plan he laid down. First 
 we may notice his admirable invention of the double 
 names. It had been the custom to designate plants 
 and animals according to some name common to a 
 large group, to which was added a description more 
 or less characteristic. An idea may be formed of 
 the necessity of a reform by conceiving what a la- 
 borious and uncertain task it would be if our friends 
 spoke to us of having seen a dog in the garden, and 
 on our asking what kind of a dog, instead of their 
 saying " a terrier, a bull-terrier, or a Skye-terrier," 
 they were to attempt a description of the dog. 
 Something of this kind was the labor of under- 
 standing the nature of an animal from the vague 
 description of it given by naturalists. Linnaeus 
 rebaptized the whole animal kingdom upon one 
 intelligible principle. He continued to employ the 
 name common to each group, such as that of Felis 
 for the cats, which became the generic name ; and 
 in lieu of the description which was given of each 
 different kind to indicate that it was a lion, a tiger, 
 a leopard, or a domestic cat, he affixed a specific 
 name : thus the animal bearing the description of a 
 lion became Felis leo ; the tiger, Felis tigris ; the 
 leopard, Felis leopardus ; and our domestic friend, 
 Felis catus. These double names, as Yogt remarks, 
 are like the Christian- and sur-names by which we 
 distinguish the various members of one family ; and 
 instead of speaking of Tomkinson with the flabby 
 
92 STUDIES IN ANIMAL LIFE. 
 
 face and Tomkinson with the square forehead, we 
 simply say John and William Tomkinson. 
 
 Linnaeus did more than this. He not only fixed 
 definite conceptions of species and genera, but in- 
 troduced those of orders and classes. Cuvier added 
 families to genera, and sub-kingdoms (embranclie- 
 menis) to classes. Thus a scheme was elaborated 
 by which the whole animal kingdom was arranged 
 in subordinate groups : the sub-kingdoms were di- 
 vided into classes, the classes into orders, the orders 
 into families, the families into genera, the genera 
 into species, and the species into varieties. The 
 guiding principle of anatomical resemblance determ- 
 ined each of these divisions. Those largest groups, 
 which resemble each other only in having what is 
 called the typical character in common, are brought 
 together under the first head. Thus all the groups 
 which agree in possessing a backbone and internal 
 skeleton, although they differ widely in form, struc- 
 ture, and habitat, do nevertheless resemble each 
 other more than they resemble the groups which 
 have no backbone. This great division having been 
 formed, it is seen to arrange itself in very obvious 
 minor divisions or classes the mammalia, birds, 
 reptiles, and fishes. All mammals resemble each 
 other more than they resemble birds ; all reptiles 
 resemble each other more than they resemble fishes 
 (in spite of the superficial resemblance between ser- 
 pents and eels or lampreys). Each class, again, 
 falls into the minor groups of orders, and on the 
 
STUDIES IN ANIMAL LIFE. 93 
 
 same principles the monkeys being obviously dis- 
 tinguished from rodents, and the carnivora from 
 the ruminating animals ; and so of the rest. In each 
 order there are generally families, and the families 
 fall into genera, which differ from each other only 
 in fewer and less important characters. The genera 
 include groups which have still fewer differences, 
 and are called species; and these, again, include 
 groups which have only minute and unimportant 
 differences of color, size, and the like, and are call- 
 ed sub-species, or varieties. 
 
 "Whoever looks at the immensity of the animal 
 kingdom, and observes how intelligibly and system- 
 atically it is arranged in these various divisions, 
 will admit that, however imperfect, the scheme is a 
 magnificent product of human ingenuity and labor. 
 It is not an arbitrary arrangement, like the group- 
 ing of the stars in constellations; it expresses, 
 though obscurely, the real order of Nature. All 
 true classification should be to forms what laws are 
 to phenomena; the one reducing varieties to sys- 
 tematic order, as the other reduces phenomena to 
 their relation of sequence. Now if it be true that 
 the classification expresses the real order of Nature, 
 and not simply the order which we may find con- 
 venient, there will be something more than mere 
 resemblance indicated in the various groups; or, 
 rather let me say, this resemblance itself is the con- 
 sequence of some community in the things com- 
 pared, and will therefore be the mark of some deep- 
 
94 STUDIES IN ANIMAL LIFE. 
 
 er cause. What is this cause ? Mr. Darwin holds 
 that "propinquity of descent the only known 
 cause of the similarity of organic beings is the 
 bond, hidden as it is by various degrees of modifi- 
 cation, which is partially revealed to us by our 
 classifications"* " that the characters which natu- 
 ralists consider as showing true affinity between 
 any two or more species are those which have been 
 inherited from a common parent, and in so far all 
 true classification is genealogical; that community 
 of descent is the hidden bond which naturalists 
 have been unconsciously seeking, and not pome 
 unknown plan of creation, or the enunciation of 
 general propositions, and the mere putting together 
 and separating objects more or less alike."f 
 
 Before proceeding to open the philosophical dis- 
 cussion which inevitably arises on the mention of 
 Mr. Darwin's book, I will here set down the chief 
 groups, according to Cuvier's classification, for the 
 benefit of the tyro in natural history, who will easi- 
 ly remember them, and will find the knowledge 
 constantly invoked. 
 
 There are four sub-kingdoms, or branches : 1. 
 Vertebrata; 2. Mollusca; 3. Articulata; 4. Eadi- 
 ata. 
 
 The YERTEBKATA consist of four classes : Mam- 
 malia, Birds, Eeptiles, and Fishes. 
 
 The MOLLUSCA consist of six classes : Cephalo- 
 poda (cuttlefish), Pteropoda, Gasteropoda (snails, 
 
 * DARWIN : Origin of Species, p. 414. f Ibid., p. 420. 
 
STUDIES IN ANIMAL LIFE. 95 
 
 etc.), Acephala (oysters, etc.), Brachiopoda, and Cir- 
 rhopoda (barnacles). N.B. This last class is now 
 removed from the Mollusks and placed among the 
 Crustaceans. 
 
 The ARTICULATA are composed of four classes : 
 Annelids (worms), Crustacea (lobsters, crabs, etc.), 
 Arachnida (spiders), and Insecta. 
 
 The KADLATA embrace all the remaining forms; 
 but this group has been so altered since Cuvier's 
 time that I will not burden your memory just now 
 with an enumeration of the details. 
 
 The reader is now in a condition to appreciate 
 the general line of argument adopted in the discus- 
 sion of Mr. Darwin's book, which is at present ex- 
 citing very great attention, and which will, at any 
 rate, aid in general culture by opening to many 
 minds new tracts of thought. The benefit in this 
 direction is, however, considerably lessened by the 
 extreme vagueness which is commonly attached to 
 the word " species," as well as by the great want of 
 philosophic culture which impoverishes the major- 
 ity of our naturalists. I have heard or read few 
 arguments on this subject which have not impress- 
 ed me with the sense that the disputants really at- 
 tached no distinct ideas to many of the phrases they 
 were uttering. Yet it is obvious that we must first 
 settle what are the facts grouped together and indi- 
 cated by the word " species," before we can carry 
 on any discussion as to the origin of species. To 
 be battling about the fixity or variability of species, 
 
96 STUDIES IN ANIMAL LIFE. 
 
 without having rigorously settled what species is, 
 
 can lead to no edifying result. 
 
 It is notorious that if you ask even a zoologist, 
 
 What is a species? you will always find that he 
 has only a very vague answer to give ; and if his 
 answer be precise, it will be the precision of error, 
 and will vanish into contradictions directly it is ex- 
 amined. The consequence of this is, that even the 
 ablest zoologists are constantly at variance as to 
 specific characters, and often can not agree whether 
 an animal shall be considered of a new species or 
 only a variety. There could be no such disagree- 
 ments if specific characters were definite if we 
 knew what species meant, once and for all. Ask a 
 chemist, What is a salt ? What an acid ? and his 
 reply will be definite and uniformly the same: 
 what he says all chemists will repeat. Not' so the 
 zoologist. Sometimes he will class two animals as 
 of different species, when they only differ in color, 
 in size, or in the numbers of tentacles, etc. ; at other 
 times he will class animals as belonging to the same 
 species, although they differ in size, color, shape, in- 
 stincts, habits, etc. The dog, for example, is said to 
 be one species with many varieties or races. But 
 contrast the pug-dog with the greyhound, the span- 
 iel with the mastiff, the bull-dog with the Newfound- 
 land, the setter with the terrier, the sheep-dog with 
 the pointer; note the striking differences in their 
 structure and their instincts, and you will find that 
 they differ as widely as some genera and as some 
 
STUDIES IN ANIMAL LIFE. 97 
 
 species. If these varieties inhabited different coun- 
 tries if the pug were peculiar to Australia and the 
 mastiff to Spain there is not a naturalist but would 
 class them as of different species. The same re- 
 mark applies to pigeons and ducks, oxen and sheep. 
 The reason of this uncertainty is that the thing 
 species does not exist : the term expresses an ab- 
 straction, like virtue, or whiteness ; not a definite 
 concrete reality, which can be separated from other 
 things, and always be found the same. Nature pro- 
 duces individuals ; these individuals resemble each 
 other in varying degrees ; according to their resem- 
 blances we group them together as classes, orders, 
 genera, and species; but these terms only express 
 the relations of resemblance, they do not indicate the 
 existence of such things as classes, orders, genera, or 
 species.* There is a reality indicated by each term 
 that is to say, a real relation ; but there is no ob- 
 jective existence of which we could say, This is 
 variable, This is immutable. Precisely as there is 
 a real relation indicated by the term goodness, but 
 there is no goodness apart from the virtuous actions 
 and feelings which we group together under this 
 term. It is true that metaphysicians in past ages 
 angrily debated respecting the immutability of vir- 
 tue, and had no more suspicion of their absurdity 
 than moderns have who debate respecting the fixity 
 
 * CUVIER says, in so many words, that classes, orders, and gen- 
 era are abstractions, et rien de pareil n'existe dans la nature ; but 
 species is not an abstraction ! See Lettres a Pfaff, p. 179. 
 
 E 
 
98 STUDIES IN ANIMAL LIFE. 
 
 of species. Yet no sooner do we understand that 
 species means a relation of resemblance between 
 animals, than the question of the fixity or varia- 
 bility of species resolves itself into this : Can there 
 be any variation in the resemblances of closely al- 
 lied animals? A question which would never be 
 asked. 
 
 No one has thought of raising the question of 
 the fixity of varieties, yet it is as legitimate as that 
 of the fixity of species ; and we might also argue 
 for the fixity of genera, orders, classes, the fixity of 
 all these being implied in the very terms ; since no 
 sooner does any departure from the type present 
 itself, than ~by that it is excluded from the category ; 
 no sooner does a white object become gray or yel- 
 low, than it is excluded from the class of white ob- 
 jects. Here, therefore, is a sense in which the phrase 
 " fixity of species" is indisputable ; but in this sense 
 the phrase has never been disputed. When zoolo- 
 gists have maintained that species are variable, they 
 have meant that animal forms are variable; and 
 these variations, gradually accumulating, result at 
 last in such differences as are called specific. Al- 
 though some zoologists, and speculators who were 
 not zoologists, have believed that the possibility of 
 variation is so great that one species may actually 
 be transmuted into another, i. e., that an ass may be 
 developed into a horse, yet most thinkers are now 
 agreed that such violent changes are impossible, 
 and that every new form becomes established only 
 
STUDIES IN ANIMAL LIFE. 99 
 
 through the long and gradual accumulation of mi- 
 nute differences in divergent directions. 
 
 It is clear, from what has just been said, that the 
 many angry discussions respecting the fixity of spe- 
 cies, which, since the days of Lamarck, have dis- 
 turbed the amity of zoologists and speculative phi- 
 losophers, would have been considerably abbrevia- 
 ted-had men distinctly appreciated the equivoque 
 which rendered their arguments hazy. I am far 
 from implying that the battle was purely a verbal 
 one. I believe there was a real and important dis- 
 tinction in the doctrines of the two camps ; but it 
 seems to me that, had a clear understanding of the 
 fact that species was an abstract term been uniform- 
 ly present to their minds, they would have sooner 
 come to an agreement. Instead of the confusing 
 disputes as to whether one species could ever be- 
 come another species, the question would have been, 
 Are animal forms changeable? Can the descend- 
 ants of animals become so unlike their ancestors, in 
 certain peculiarities of structure or instinct, as to be 
 classed by naturalists as a different species ? 
 
 ISTo sooner is the question thus disengaged from 
 equivoque than its discussion becomes narrowed 
 within well-marked limits. That animal forms are 
 variable is disputed by no zoologist. The only 
 question which remains is this : To what extent are 
 animal forms variable? The answers given have 
 been two : one school declaring that the extent of 
 variability is limited to those trifling characteristics 
 
100 STUDIES IN ANIMAL LIFE. 
 
 which mark the different varieties of each species ; 
 the other school declaring that the variability is in- 
 definite, and that all animal forms may have arisen 
 from successive modifications of a very few types, 
 or even of one type. 
 
 Now I would call your attention to one point in 
 this discussion which ought to be remembered when 
 antagonists are growing angry and bitter over the 
 subject; it is, that both these opinions are necessa- 
 rily hypothetical there can be nothing like posi- 
 tive proof adduced on either side. The utmost that 
 either hypothesis can claim is that it is more con- 
 sistent with general analogies, and better serves to 
 bring our knowledge of various points into har- 
 mony. Neither of them can claim to be a truth 
 which warrants dogmatic decision. 
 
 Of these two hypotheses, the first has the weight 
 and majority of authoritative adherents. It de- 
 clares that all the different kinds of bats, for exam- 
 ple, were distinct and independent creations, each 
 species being originally what we see it to be now, 
 and what it will continue to be as long as it ex- 
 ists : lions, panthers, pumas, leopards, tigers, jagu- 
 ars, ocelots, and domestic cats being so many origi- 
 nal stocks, and not so many divergent forms of one orig- 
 inal stock. The second hypothesis declares that all 
 these kinds of cats represent divergencies of the 
 original stock, precisely as the varieties of each kind 
 represent the divergencies of each species. It is 
 true that each species, when once formed, only ad- 
 
STUDIES IN ANIMAL LIFE. 101 
 
 mits of limited variations ; any cause which should 
 push the variation beyond certain limits would de- 
 stroy the species, because by species is meant the 
 group of animals contained within those limits. Let 
 us suppose the original stock from which all these 
 kinds of cats have sprung to have become modified 
 into lions, leopards, and tigers in other words, that 
 the gradual accumulation of divergencies has re- 
 sulted in the whole family of cats existing under 
 these three forms. The lions will form a distinct 
 species; this species varies, and in the course of 
 long variation a new species, the puma, rises by the 
 side of it. The leopards also vary, and let us sup- 
 pose their variation at length assumes so marked a 
 form in the ocelot that we class it as a new spe- 
 cies. There is nothing in this hypothesis but what 
 is strictly consonant with analogies; it is only ex- 
 tending to species what we know to be the fact 
 with respect to varieties ; and these varieties which 
 we know to have been produced from" one and the 
 same species are often more widely separated from 
 each other than the lion is from the puma, or the 
 leopard from the ocelot. Mr. Darwin remarks that 
 " at least a score of pigeons might be chosen, which, 
 if shown to an ornithologist, and he were told that 
 they were wild birds, would certainly, I think, be 
 ranked by him as well-defined species. Moreover, 
 I do not believe that any ornithologist would place 
 the English carrier, the short-faced tumbler, the 
 runt, the barb, the pouter, and fantail in the same 
 
102 STUDIES IN ANIMAL LIFE. 
 
 genus, more especially as in each, of these breeds 
 several truly -inherited sub-breeds or species, as he 
 might have called them, could be shown him." 
 
 The development of numerous specific forms, 
 widely distinguished from each other, out of one 
 common stock, is not a whit more improbable than 
 the development of numerous distinct languages 
 out of a common parent language, which modern 
 philologists have proved to be indubitably the case. 
 Indeed, there is a very remarkable analogy between 
 philology and zoology in this respect: just as the 
 comparative anatomist traces the existence of simi- 
 lar organs, and similar connections of these organs, 
 throughout the various animals classed under one 
 type, so does the comparative philologist detect the 
 family likeness in the various languages scattered 
 from China to the Basque Provinces, and from Cape 
 Comorin across the Caucasus to Lapland a like- 
 ness which assures him that the Teutonic, Celtic, 
 Wendic, Italic, Hellenic, Iranic, and Indie languages 
 are of common origin, and separated from the Ara- 
 bian, Aramean, and Hebrew languages, which have 
 another origin. Let us bring together a French- 
 man, a Spaniard, an Italian, a Portuguese, a Walla- 
 chian, and a Khastian, and we shall hear six very 
 different languages spoken, the speakers severally 
 unintelligible to each other, their languages differ- 
 ing so widely that one can not be regarded as the 
 modification of the other ; yet we know most posi- 
 tively that all these languages are offshoots from 
 
STUDIES IN ANIMAL 
 
 the Latin, which was once a living language, but 
 which is now, so to speak, a fossil. The various 
 species of cats do not differ more than these six 
 languages differ, and yet the resemblances point in 
 each case to a common origin. Max Muller, in his 
 brilliant essay on Comparative Mythology* has said, 
 " If we knew nothing of the existence of Latin 
 if all historical documents previous to the fifteenth 
 century had been lost if tradition, even, was silent 
 as to the former existence of a Eoman empire, a 
 mere comparison of the six Eoman dialects would 
 enable us to say that at some time there must have 
 been a language from which all these modern dia- 
 lects derived their origin in common ; for without 
 this supposition it would be impossible to account 
 for the facts exhibited by these dialects. Let us 
 look at the auxiliary verb. "We find : 
 
 Italian. Wallachian. Rhsetian. Spanish. Portuguese. French. 
 I am sono sum sunt sunt soy sou suis. 
 
 Thou art sei es eis erea es es. 
 
 He is e < (este) ei es he est. 
 
 We are siamo suntemu essen somos somos sommes. 
 
 You are siete suntefi esses sois sois etes (estes). 
 
 They are sono sunt eon (sun) son eao sent. 
 
 It is clear, even from a short consideration of these 
 forms, first, that all are but varieties of one common 
 type ; secondly, that it is impossible to consider any 
 one of these six paradigms as the original from 
 which the others had been borrowed. To this we 
 may add, thirdly, that in none of the languages to 
 which these verbal forms belong do we find the 
 
 * See Oxford Essays, 1856. 
 
104 STUDIES IN ANIMAL LIFE. 
 
 elements of which they could have been composed. 
 If we find such forms as f ai aime, we can explain 
 them by a mere reference to the radical means which 
 French has still at its command, and the same may 
 be said even of compounds like f aimer ai, i. e., je- 
 aimer-ai, I have to love, I shall love. But a change 
 from je suis to tu es is inexplicable by the light of 
 French grammar. These forms could not have 
 grown, so to speak, on French soil, but must have 
 been handed down as relics from a former period 
 must have existed in some language antecedent to 
 any of the Eoman dialects. Now, fortunately, in 
 this case, we are not left to a mere inference, but as 
 we possess the Latin verb, we can prove how, by 
 phonetic corruption and by mistaken analogies, 
 every one of the six paradigms is but a national 
 metamorphosis of the Latin original. 
 
 "Let us now look at another set of paradigms : 
 
 Sanscrit. j|j Zend. Doric. sla U ic> Latin. Gothic. Armen. 
 
 I am asmi esmi ahmi enm yesmo sum im em. 
 
 Thou art asi essi ahi e<ro-i yesi ea is es. 
 
 He is asti esti asti ka-ri yesto est ist e. 
 
 We (two) are . . 'svas esva yesva . . . eiju 
 
 You (two) are. . 'sthas esta stho? eo-rov yesta ... sijuts ... 
 
 They (two) are. 'stas (esti) sto? ea-rov yesta 
 
 We are 'smas esmi hmahi eoyxer yesmo sumus sijum emq. 
 
 You are 'stha este stha eo-re yeste estis sijup eq. 
 
 They are santi (esti) h^nti ev-ri somtS sunt sind en. 
 
 " From a careful consideration of these forms, we 
 ought to draw exactly the same conclusions ; first- 
 ly, that all are but varieties of one common type ; 
 secondly, that it is impossible to consider any of 
 them as the original from which the others have 
 
STUDIES IN ANIMAL LIFE. 105 
 
 been borrowed ; and, thirdly, that here again none 
 of the languages in which these verbal forms occur 
 possess the elements of which they are composed." 
 
 All these languages resemble each other so close- 
 ly that they point to some more ancient language 
 which was to them what Latin was to the six Ko- 
 man languages ; and in the same way we are justi- 
 fied in supposing that all the classes of the verte- 
 brate animals point to the existence of some elder 
 type, now extinct, from which they were all de- 
 veloped. 
 
 I have thus stated what are the two hypotheses 
 on this question. There is only one more prelimi- 
 nary which it is needful to notice here, and that is, 
 to caution the reader against the tendency, unhap- 
 pily too common, of supposing that an adversary 
 holds opinions which are transparently absurd. 
 When we hear a hypothesis which is either novel 
 or unacceptable to us, we are apt to draw some very 
 ridiculous conclusion from it, and to assume that 
 this conclusion is seriously held by its upholders. 
 Thus the zoologists who maintain the variability 
 of species are sometimes asked if they believe a 
 goose was developed out of an oyster, or a rhinoce- 
 ros from a mouse ? the questioner apparently having 
 no misgiving as to the candor of his ridicule. There 
 are three modes of combating a doctrine. The first 
 is to point out its strongest positions, and then 
 show them to be erroneous or incomplete ; but this 
 plan is generally difficult, and sometimes impossi- 
 E2 
 
106 STUDIES IN ANIMAL LIFE. 
 
 ble ; it is not, therefore, much in vogue. The sec- 
 ond is to render the doctrine ridiculous by pretend- 
 ing that it includes certain extravagant propositions 
 of which it is entirely innocent. The third is to 
 render the doctrine odious by forcing on it certain 
 conclusions which it would repudiate, but which are 
 declared to be " the inevitable consequences" of such 
 a doctrine. JSTow it is undoubtedly true that men 
 frequently maintain very absurd opinions; but it 
 is neither candid nor wise to assume that men who 
 otherwise are certainly not fools, hold opinions the 
 absurdity of which is transparent. 
 
 Let us not, therefore, tax the followers of La- 
 marck, Greoffroy St. Hilaire, or Mr. Darwin with ab- 
 surdities they have not advocated, but rather en- 
 deavor to see what solid argument they have for 
 the basis of their hypothesis. 
 
STUDIES IN ANIMAL LIFE. 107 
 
 CHAPTER Y. 
 
 Talking in Beetles. Identity of Egyptian Animals with those now 
 existing : Does this prove Fixity of Species ? Examination of 
 the celebrated Argument of Species not having altered in four 
 thousand Years. Impossibility of distinguishing Species from 
 Varieties. The Affinities of Animals. New Facts proving the 
 Fertility of Hybrids. The Hare and the Rabbit contrasted. 
 Doubts respecting the Development Hypothesis. On Hypoth- 
 esis in Natural History. Pliny, and his Notion on the Forma- 
 tion of Pearls. Are Pearls owing to a Disease of the Oyster ? 
 Formation of the Shell; Origin of Pearls. How the Chinese 
 manufacture Pearls. * 
 
 A WITTY friend of mine expressed her sense of 
 the remoteness of the ancient Egyptians, and her 
 difficulty in sympathizing with them, by declar- 
 ing that " they talked in beetles, you know.' 1 ' 1 She 
 referred, of course, to the hieroglyphics in which 
 that curious people now speak to us from ancient 
 tombs. Whether these swarthy sages were elo- 
 quent and wise, or obscure and otherwise, in their 
 beetle-speech, it is certain that entomologists of our 
 day recognize their beetles as belonging to the same 
 species that are now gathered into collections. Such 
 as the Egyptians knew them, such we know them 
 now. Nay, the sacred cats found in those ancient 
 tombs are cats of the same kind as our own familiar 
 mousers ; they purred before Pharaoh as they purr 
 
108 STUDIES IN ANIMAL LIFE. 
 
 on our hearth-rugs; and the descendants of the 
 very dogs which irreligiously worried those cats 
 are to this day worrying the descendants of those 
 sacred cats. The grains of wheat which the savans 
 found in the tombs were planted in the soil of 
 France, and grew into waving corn in no respect 
 distinguishable from the corn grown from the grain 
 of the previous year. 
 
 Have these familiar facts any important signifi- 
 cance? Are we entitled to draw any conclusion 
 from the testimony of paintings and sculptures, at 
 least four thousand years old, which show that sev- 
 eral of our well-known species of animals, and sev- 
 eral of the well-marked races of men, existed then, 
 and have not changetfsince then ? Nimrod hunted 
 with dogs and horses, which would be claimed as 
 ancestors by the dogs and horses at Melton Mow- 
 bray. The negroes who attended Semiramis and 
 Khamses are in every respect similar to the negroes 
 now toiling amid the sugar-canes of Alabama. If, 
 during four thousand years, species and races have 
 not changed, why should we suppose that they ever 
 will change ? Why should we not take our stand 
 on that testimony, and assert that species are un- 
 changeable ? 
 
 Such has been the argument of Cuvier and his 
 followers; an argument on which they have laid 
 great stress, and which they have further strength- 
 ened by a challenge to adversaries to produce one 
 single case where a transmutation of species has 
 
STUDIES IN ANIMAL LIFE. 109 
 
 taken place: "Here we show you evidence that 
 species has persisted unaltered during four thousand 
 years, and you can not show us a single case of 
 species having changed you can not show us one 
 case of a wolf becoming a dog, an ass becoming a 
 horse, a hare becoming a rabbit. Yet you must 
 admit that if there were any inherent tendency 
 to change, four thousand years is a long enough 
 period for that tendency to display itself in ; and 
 we ought to see a very marked difference between 
 the species which lived under Semiramis and those 
 which are living under Victoria. Instead of this, 
 we see that there has been no change : the dog has 
 remained a dog, and the horse has remained a 
 horse ; every species retains its well-marked char- 
 acters." 
 
 No one will say that I have not done justice to 
 this argument. I have stated it as clearly and for- 
 cibly as possible, not with any design to captivate 
 your assent, but to make the answer complete. 
 This argument is the cheval de batailk of the Cuvier 
 school ; but, like many other argumentative war- 
 horses, it proves, on close inspection, to be spavined 
 and broken-winded. The first criticism we must 
 pass on it is that it implies the existence of species 
 as a thing which can be spoken of as fixed or varia- 
 ble ; whereas, as we saw in the last chapter, species 
 is an abstraction, like whiteness or strength. No one 
 supposes that there exists any whiteness apart from 
 white things, or strength apart from strong things ; 
 
110 STUDIES IN ANIMAL LIFE. 
 
 yet the naturalists who maintain the fixity of spe- 
 cies constantly talk as if species existed independ- 
 ently of the individual animals. Instead of saying 
 that by the word species is indicated a certain group 
 of characters, and that whenever we meet with this 
 group we say, here is an animal of the same spe- 
 cies, they explicitly declare, or tacitly imply, that al- 
 though an individual dog may vary, there is some- 
 thing above all individuals the species and that 
 can not vary. As it is possible some readers may 
 protest that no respectable authority in modern 
 times ever held the opinion here imputed to a 
 school, I will quote the very explicit language of 
 one of Cuvier's disciples the last editor of Buffon 
 who, no later than 1856, could declare that " spe- 
 cies are the primitive forms of Nature. Individu- 
 als are nothing but the representatives the copies 
 of these forms: Les espbces sont les formes primitives 
 de la Nature. Les individus n'en sont que des repre- 
 sentations, des copies."* According to this very ex- 
 plicit but very extravagant statement, an individual 
 dog is nothing but a copy of the primitive form 
 the typical dog the idea of a dog, as Plato would 
 say ; and, of course, if this be true, it matters little 
 how widely individual dogs may vary, the type, or 
 species, of which it is the representative, remains 
 unaltered. Indeed, it is on this ground that many 
 physiologists explain the fact of hereditary trans- 
 mission: the individual may vary, it is said, but 
 
 * FLOURENS : Cours de Physioloyie Comparee, 1856, p. 9. 
 
STUDIES IN ASTTMAL LIFE. Ill 
 
 the species is preserved ; and if a dog without its 
 fore paws has offspring, every one of which pos- 
 sesses the fore paws, the reason is, that Tidee de 
 Tespece se reproduit dans le fruit, et lui donne des or- 
 ganes qui manquaient au pbre ou d la mere* It is 
 not easy to understand how the idea of a species can 
 reproduce itself, and give the offspring of a dog the 
 organs which were wanting in the parents ; but to 
 those who believe that species exist independently 
 of individuals, and form the only real existences, 
 the conception may be easier. 
 
 I have too much respect for the reader to drag 
 him through a refutation of such philosophy as 
 this ; the statement of the opinion is enough. And 
 yet, unless some such opinion be maintained, the 
 doctrine of fixity of species is without a basis ; for 
 if it be said that the group of characters which con- 
 stitute the dog are incapable of change, and in this 
 sense species are fixed, we have to ask what evi- 
 dence there can be for such an assertion? since it 
 is notorious that individual dogs do show a change 
 in some of the characters of the group. We shall 
 be referred to the Egyptian tombs for evidence. 
 M. Flourens assures us that not only are these 
 tombs evidence that species have not changed in 
 four thousand years, but that no species has changed 
 aucune espece n'a change which is surely stepping 
 a long way beyond the precincts of the tombs ! 
 
 It may be paradoxical, but it is strictly true, that 
 
 * BUKDACH : Physiologic, ii., 245. 
 
112 STUDIES IN ANIMAL LIFE. 
 
 the fact of particular species having remained un- 
 altered during four thousand years does not add 
 the slightest weight to the evidence in favor of the 
 fixity of species. " What !" some may exclaim, " do 
 you pretend that four thousand years is not a period 
 long enough to prove the fixity of animal forms ?" 
 Yes ; I affirm that four thousand, or forty thousand, 
 prove no more than four. It is only by a fallacy 
 that the opposite opinion could gain acceptance. 
 You would not suppose that I had strengthened 
 my case if, instead of contenting myself with stating 
 reasons once, I repeated these same reasons during 
 forty successive pages ; you would remind me that 
 this iteration was not cumulation, and that no force 
 was given to my fortieth assertion which the first 
 wanted. Why, then, do you ask me to accept the 
 repetition of the same fact four thousand times over 
 as an increase of evidence? It is a familiar fact 
 that like produces like that dogs resemble dogs, 
 and do not resemble buffaloes ; this fact is, of course, 
 deepened in our conviction by the unvarying evi- 
 dence we see around us, and is guaranteed by the 
 philospphical axiom that like causes produce like 
 effects ; but when once such a conception is formed, 
 it can gain no fresh strength from any particular 
 instance. If we believe that crows are black, we 
 do not hold that belief more firmly when we are 
 shown that crows were black four thousand years 
 ago. In like manner, if it is an admitted fact that 
 individuals always reproduce individuals closely re- 
 
STUDIES IN ANIMAL LIFE. 113 
 
 sembling themselves, it is not a whit more surpris- 
 ing that the dogs of Victoria should resemble the 
 dogs of Semiramis, than that they should resemble 
 their parents : the chain of four thousand years is 
 made up of many links, each link being a repetition 
 of the other. So long as a single pair of dogs re- 
 sembling each other unite, so long will there be 
 specimens of that species, simply because the chil- 
 dren inherit the characteristics of the parents. So 
 long as negroes marry with negroes, and Jews with 
 Jews, so long must there be a perpetuation of the 
 negro and Jewish types ; but the tenth generation 
 adds nothing to the evidence of the first, nor the 
 ten thousandth to the tenth. 
 
 I believe that this fallacy, which destroys the 
 whole value of the Cuvierian argument, has not 
 before been pointed out ; and even now you may 
 perhaps ask if the fixity of species is not proved by 
 the fact that like produces like? So far from this, 
 that it is only by the aid of such a fact in organic 
 nature that we can imagine new species to have 
 arisen ; in other words, those who believe in the 
 variability of species, and the introduction of new 
 forms by means of modification from the old, al- 
 ways invoke the law of hereditary transmission as 
 the means of establishing accidental variations. 
 Thus, let us suppose the Egyptian king to have 
 had one hundred dogs, all of them staghounds, and 
 no other form of dog to have existed at that time 
 in that country ; the dog species would be repre- 
 
114 STUDIES IN ANIMAL LIFE. 
 
 sented by the staghound. These staghounds would 
 transmit to their offspring all their specific charac- 
 ters. But, as every one knows, however much dogs 
 may resemble each other, they always present in- 
 dividual differences in size, color, strength, intelli- 
 gence, etc. Now, if any one of these differences 
 should happen to become marked, and to increase 
 by the intermarriage of two dogs similarly distin- 
 guished by the marked peculiarity, this peculiarity 
 would in time become established by hereditary 
 transmission, and would form the starting-point of 
 a new race of dogs say the greyhound unless it 
 were obliterated by intermarriage with dogs of the 
 old type. In the former case, we should have two 
 races of dogs among the descendants of those fig- 
 ured on the Egyptian tombs; but as one of these 
 races would still preserve the original staghound 
 type, Cuvier would refer to it as a proof that spe- 
 cies had not varied. "We, on the other hand, should 
 point to the greyhound as proof that animal forms 
 are variable, and that a new form had arisen from 
 modification of the old. 
 
 An objection will at once be raised to this illus- 
 tration, to the effect that all zoologists admit the 
 possibility of new varieties or races being formed ; 
 but they deny that new species can be formed. It 
 is here that the equivoque of the word species pre- 
 vents a clear understanding of each other's argu- 
 ment. "Whiteness may justly be said to be unalter- 
 able; but white things may vary they may be- 
 
STUDIES IN ANIMAL LIFE. 115 
 
 come gray or yellow. In like manner species must 
 be invariable, because species is a word indicating 
 a particular group of characters ; but animals may 
 vary in these characters: they may present some 
 of the characters less or more developed, and they 
 may even want some of them. Now, as there is 
 no absolute standard of what constitutes species, 
 what sub-species, and what varieties, it becomes 
 impossible to say whether any individual variation 
 in an animal form shall constitute a new variety or 
 a new species. "With regard to dogs, the differ- 
 ences between the various races are so numerous 
 and so marked as would suffice to constitute spe- 
 cies, and even genera, in other groups of animals. 
 
 "We must relinquish the idea of proving any 
 thing by the paintings and sculptures of the an- 
 cients. When we find an Egyptian plow closely 
 resembling the plow still in use in some places, we 
 may identify it as of the same " species" as our 
 own ; but this does not disprove the fact that steam- 
 plows, and plows of various construction, have 
 been since invented, all of them being modifica- 
 tions of the original type. Formerly, and for many 
 years, the stage-coach was our approved mode of 
 conveyance and it is still kept up in some dis- 
 tricts ; nevertheless, modifications of coachroad into 
 tramroad, and tramroad into railroad, have gradu- 
 ally resulted in a mode of conveyance utterly un- 
 like the stage-coach. It is the same with animals. 
 
 Let us never forget that species have no exist- 
 
116 STUDIES IN ANIMAL LIFE. 
 
 ence. Only individuals exist, and these all vary 
 more or less from each other. When the modifica- 
 tions are slight, they have no name ; when they are 
 more marked, and are transmitted from one gener- 
 ation to another, they constitute particular races or 
 varieties ; when the differences are still more mark- 
 ed, they constitute sub-species ; but, as Mr. Darwin 
 says, " Certainly no clear line of demarkation has 
 yet been drawn between species and sub-species; 
 that is, the forms which in the opinion of some nat- 
 uralists come very near to, but do not quite arrive 
 at the rank of species ; or again, between sub-spe- 
 cies and well-marked varieties, or between lesser 
 varieties and individual differences. These differ- 
 ences blend into each other in an insensible series ; 
 and a series impresses the mind with the idea of an 
 actual passage." But the same process of diverg- 
 ence which establishes varieties out of individual 
 differences, and species out of varieties, also serves 
 to establish genera out of species, orders out of gen- 
 era, and classes out of orders. It is doubtless diffi- 
 cult to conceive by what process of modification 
 two animals of distinct genera, say a dog and a cat, 
 were produced from a common stock ; but organic 
 analogies in abundance render it easy of belief. If 
 we knew as much of zoology as we do of embryol- 
 ogy, in respect of the affinities of divergent forms, 
 it would be far less surprising that two different 
 genera should arise from a common stock, than that 
 all the various parts of the skeleton should arise 
 
STUDIES IN ANIMAL LIFE. 117 
 
 from a common osseous element. "We know that 
 the jaws are identical with arms and legs both be- 
 ing divergent modifications of a common osseous 
 structure. We know that the arm of a man is 
 identical with the fin of a whale or the wing of a 
 bird. The differences here in form, size, and func- 
 tion are much greater than the differences which 
 establish orders and classes in the animal series. 
 Unless animal forms were modifications of some 
 common type, it would be difficult to explain their 
 remarkable affinities. As Mr. Darwin says, " It is 
 a truly wonderful fact the wonder of which we 
 are apt to overlook from familiarity that all ani- 
 mals and all plants throughout all time and space 
 should be related to each other in group subordi- 
 nate to group, in the manner which we every where 
 behold, namely, varieties of the same species most 
 closely related together, species of the same genus 
 less closely and unequally related together, forming 
 sections and sub-genera, species of distinct genera 
 much less closely related, and genera related in dif- 
 ferent degrees, forming sub-families, families, orders, 
 sub-classes, and classes. The several subordinate 
 groups in any class can not be ranked in a single 
 file, but seem rather to be clustered round points, 
 and these round other points, and so on in almost 
 endless circles. On the view that each species has 
 been independently created, I can see no explana- 
 tion of this great fact in the classification of all or- 
 ganic beings ; but, to the best of my judgment, it is 
 
118 STUDIES IN ANIMAL LIFE. 
 
 explained through, inheritance, and the complex 
 action of natural selection entailing extinction and 
 divergence of character. The affinities of all the 
 beings of the same class have sometimes been rep- 
 resented by a great tree. I believe this simile 
 largely speaks the truth. The green and budding 
 twigs may represent existing species, and those pro- 
 duced during each former year may represent the 
 long succession of extinct species. At each period 
 of growth all the growing twigs have tried to branch 
 out on all sides, and to overtop and kill the sur- 
 rounding twigs and branches, in the same manner 
 as species and groups of species have tried to over- 
 master other species in the great struggle for life. 
 The limbs divided into great branches, and these 
 into lesser branches, were themselves once, when 
 the tree was small, budding twigs; and this con- 
 nection of the former and present buds by ramify- 
 ing branches may well represent the classification 
 of all extinct and living species in groups subordi- 
 nate to groups. Of the many twigs which flourish- 
 ed when the tree was a mere bush, only two or 
 three, now grown into great branches, yet survive 
 and bear all the other branches ; so with the spe- 
 cies which lived during long-past geological peri- 
 ods, very few now have living and modified de- 
 scendants. ... As buds give rise by growth to 
 fresh buds, and these, if vigorous, branch out and 
 overtop on all sides many a feebler branch, so by 
 generation, I believe, it has been with the great 
 
STUDIES IN ANIMAL LIFE. 119 
 
 Tree of Life, which, fills with its dead and broken 
 branches the crust of the earth, and covers the sur- 
 face with its ever-branching and beautiful ramifica- 
 tions."* 
 
 It will not be expected that in these brief and 
 desultory remarks I should touch on all, or nearly 
 all, the important points in the discussion respect- 
 ing the fixity of species. Mr. Darwin's book is in 
 every body's hands, and my object has been to fa- 
 cilitate, if possible, the comprehension of his book, 
 and the adoption of a more philosophical hypothe- 
 sis, by pointing out the weakness of the chief argu- 
 ment on the other side. There is one more argu- 
 ment which may be noticed the more so as it is 
 constantly adduced with triumph by the one school, 
 and admitted as a difficulty by the other. Its force 
 is so great that it prevents many from accepting 
 the development hypothesis. It is the argument 
 founded on the alleged impossibility of hybrids 
 continuing the race. More than two or three gen- 
 erations of hybrids, it is said, can never be main- 
 tained; after that, the new form perishes, thus 
 clearly showing how Nature repudiates such amal- 
 gamations, and keeps her species jealously distinct 
 and invariable. This argument is held to be the 
 touchstone of the doctrine of species. I wish it 
 were so ; because, in that case, the question would 
 no longer be one of hypothesis, since we have now 
 the indubitable proof that some hybrids are fertile 
 unto the thirteenth generation and onward. 
 
 * DARWIN : Origin of Species, p. 128. 
 
120 STUDIES IN ANIMAL LIFE. 
 
 A history of the various attempts which have 
 been made to prove and disprove the fertility of 
 hybrids would lead us beyond our limits ; the curi- 
 ous reader is referred to the works cited below.* 
 One decisive case alone shall be given here, and no 
 one will dispute that it is decisive. 
 
 The hare (lepus timidus) is assuredly of a distinct 
 species from the rabbit (lepus cuniculus). So dis- 
 tinct are these species, that any classification which 
 should range them as one would violate every ac- 
 cepted principle. The hare is solitary, the rabbit 
 gregarious; the hare lives on the surface of the 
 earth, the rabbit burrows under the surface ; the 
 hare makes her home among the bushes, the rabbit 
 makes a sort of nest for her young in her burrow 
 keeping them there till they are weaned ; the hare 
 has reddish-brown flesh, the rabbit white flesh ; 
 while the odor exhaled by each, and the flavor of 
 each, are unmistakably different. The hare has 
 many anatomical characters differing from those of 
 the rabbit, such as greater length and strength of 
 the hind legs, larger body, shorter intestine, thicker 
 skin, firmer hair, and different color. The hare 
 breeds only twice or thrice a year, and at each lit- 
 ter has only two or four; the rabbit will breed 
 eight times a year, and each time has four, six, 
 seven, and even eight young ones. Finally, the 
 
 * ISIDORE GEOFFROY ST. HILAIRE : Hist. Nat. Generate des 
 Regnes Organiques, 1860, iii., 207 sq. BROCA : Memoire sur IHy- 
 bridite, in BROWN-SEQUARD'S Journal de la Physiologic, 1859. 
 
STUDIES IN ANIMAL ^, , , fir _ 
 
 SITY 
 
 two are violent foes: the rabbits always destroy 
 the hares, and all sportsmen are aware that if the 
 rabbits be suffered to multiply on an estate, there 
 will be small chance of hares. 
 
 Nevertheless, between species so distinct as these, 
 a new hybrid race has been reared by M. Eouy, of 
 Angouleme, who each year sends to market upward 
 of a thousand of his Leporides, as he calls them. 
 His object was primarily commercial, not scientific. 
 His experiments, extending from 1847 to the pres- 
 ent time, have not only been of great commercial 
 value introducing a new and valuable breed 
 but have excited the attention of scientific men, 
 who are now availing themselves of his skill and ex- 
 perience to help them in the solution of minor prob- 
 lems. It is enough to note here that these hybrids 
 of the hare and the rabbit are fertile, not only with 
 either hares or rabbits, but with each other. Thir- 
 teen generations have already been enumerated, 
 and the last remains so vigorous that no cessation 
 whatever is to be anticipated. 
 
 In presence of this case (and others, though less 
 striking, might be named) there is but one alterna- 
 tive either we must declare that rabbits and hares 
 form one and the same species which is absurd 
 or we must admit that new types may be formed "by 
 the union of two existing races ; and, consequently, 
 that species are variable. If the doctrine of fixity 
 of species acknowledges the touchstone of hybrid- 
 ity, the fate of the doctrine is settled forever. 
 F 
 
122 STUDIES IN ANIMAL LIFE. 
 
 Although I conceive the doctrine of fixity of 
 species to be altogether wrong, I can not say that 
 the arguments adduced in favor of the development 
 hypothesis rise higher than a high degree of proba- 
 bility, still very far from demonstration ; they will 
 leave even the most willing disciple beset with dif- 
 ficulties and doubts. When stated in general terms, 
 that hypothesis has a fascinating symmetry and 
 simplicity ; but no sooner do we apply it to partic- 
 ular cases, than a thick veil of mystery descends, 
 and our pathway becomes a mere blind groping to- 
 ward the light. There is nothing but what is per- 
 fectly conceivable, and in harmony with all analo- 
 gies, in the idea of all animal forms having arisen 
 from successive modifications of one original form, 
 but there are many things perfectly conceivable 
 which have nevertheless no existence ; there are 
 many explanations perfectly probable which are 
 not true ; and when we come to seek for the evi- 
 dence of the development hypothesis, that evidence 
 fails us. It may be true, but we can not say that it 
 is true. Ten years ago I espoused the hypothesis, 
 and believed that it must be the truth; but ten 
 years of study, instead of deepening, have loosened 
 that conviction : they have strengthened my oppo- 
 sition to the hypothesis of fixity of species, but 
 they have given greater force to the difficulties 
 which beset the development hypothesis, and have 
 made me feel that at present the requisite evidence 
 is wanting. I conclude with reminding the reader 
 
STUDIES IN ANIMAL LIFE. 123 
 
 that the question of the origin of species is at pres- 
 ent incapable of a positive answer ; of the two hy- 
 potheses, that of development seems the more har- 
 monious with our knowledge; but it is no more 
 than an hypothesis, and will probably forever re- 
 main one. Now an hypothesis, although indispens- 
 able as a provisional mode of grouping together 
 facts, and giving them some sort of explanation, is, 
 after all, only a guess, and it may be absurdly wide 
 of the truth. In Natural History, as in all other 
 departments of speculative ingenuity, there have 
 been a goodly number of outrageously extravagant 
 hypotheses gravely propounded and credulously 
 accepted. Men prefer an absurd guess to a blank ; 
 they would rather have 'a false opinion than no 
 opinion ; and one of the last developments of phil- 
 osophic culture is the power of abstaining from 
 forming an opinion where the necessary data are 
 absent. 
 
 If you wish to see how easily hypotheses are 
 formed and accepted, you need only turn over the 
 history of any science. If you want a laugh at 
 credulity, read a chapter of Pliny's Natural History. 
 Pliny is a classic, and was for centuries an author- 
 ity ; but, looked at with impartial eyes, he appears 
 the veriest " old woman" that ever wrote in a beau- 
 tiful style. He was a mere bookworm, without a 
 particle of scientific insight. His was not an age 
 when men had much regard to evidence ; but to 
 him the suspicion never seems to have occurred 
 
124 STUDIES IN ANIMAL LIFE. 
 
 that Gossip Eeport could be given to romancing, 
 or that travelers could "see strange things." No 
 fable is too monstrous for his credulity. 
 
 One of the pretty fables Pliny repeats is that 
 pearls are formed by drops of dew falling into the 
 gaping valves of the oyster. It never occurred to 
 him to ask whether oysters were ever exposed to 
 the dew? whether the drops could fall into their 
 valves ? whether oysters kept their valves open ex- 
 cept when under water ? or, finally, whether, if the 
 dew did fall in, it would remain a rounded drop ? 
 The drop of dew had a certain superficial resem- 
 blance to the pearl, and that was enough. Julian's 
 hypothesis was somewhat better : he supposed that 
 the pearls were produced by lightning flashing into 
 the open shells. 
 
 Turning from these ancient sages, you will ask 
 how pearls are formed ? And almost any ingenious 
 modern, not a zoologist, will tell you (and tell you 
 falsely) that the pearl is a disease of the oyster. 
 One is somewhat fatigued at the merciless frequen- 
 cy with which this notion has been dragged in, as 
 an illustration of genius issuing out of sorrow and 
 adversity, and it is time to stop that " damnable 
 iteration" by discrediting the notion. Know then 
 that if 
 
 " Most wretched men 
 Are cradled into poetry by wrong, 
 They learn in suffering what they teach in song" 
 
 it is not true that oysters secrete in suffering what 
 
STUDIES IN ANIMAL LIFE. 125 
 
 women wear as necklaces. Disease would be the 
 very worst cradle for pearls. The idea of disease 
 originated in a fanciful supposition of pearls being 
 to the oyster and mussel what gall-stones and uri- 
 nary calculi are to higher and more suffering ani- 
 mals. Keaumur, to whom we owe so many good 
 observations and suggestive ideas, came near the 
 truth when, in 1717, he showed that the structure of 
 pearls was identical with the structure of the shells 
 in which they grow. He attributed their formation 
 to the morbid effusion of coagulating shell-material. 
 I presume you know that shells are formed by a 
 secretion from the mantle? The mantle is that 
 delicate semi-transparent membrane which you ob- 
 serve, on opening a mussel, lining the whole inte- 
 rior of the shells, and having at its free margins a 
 sort of fringe of delicate tentacles which are sensi- 
 tive and retractile. A microscopic examination of 
 these fringes shows them to be glandular in struc- 
 ture that is, they are secreting organs. The whole 
 mantle, indeed, is a secreting organ, and its secre- 
 tion is the shell-material: the fringes secrete the 
 coloring matters of the shell, and enlarge its circum- 
 ference ; the rest of the mantle secretes the nacre, 
 or mother of pearl, and increases the thickness of 
 the shell. Now it is obvious that the formation of 
 pearl nacre and of pearls depends on the healthy 
 condition of the mantle, not on its diseases. If the 
 mantle be injured, the nacre is not secreted at all, 
 or in less quantities. 
 
126 STUDIES IN ANIMAL LIFE. 
 
 But, although pearls depend upon the healthy, 
 not the diseased activity of the mantle, it is clear 
 that there must be some unusual condition present 
 for their formation, since the secretion of nacre 
 does not spontaneously assume the form of pearls. 
 What is the unusual condition ? Naturalists are at 
 present divided into two camps, fighting vigorously 
 for victory. The one side maintains that the origin 
 of a pearl is this : an egg of the oyster has escaped 
 and strayed under the mantle, or the egg of a para- 
 site has been deposited there; this egg forms the 
 nucleus round which the nacre forms, and thus we 
 have the pearl. The other side maintains with 
 great positiveness that any thing will form a nucleus, 
 a grain of sand no less than the egg of a parasite. 
 'Tis a pretty quarrel, which we may leave them to 
 settle. Some aver that grains of sand are more nu- 
 merous than any thing else ; but Mobius says that 
 of forty -four sea pearls and fifteen fresh-water pearls 
 examined by him, not one contained a grain of sand ; 
 and Filippi, who has extensively investigated this 
 subject, denies that a grain of sand ever forms the 
 nucleus of a true pearl. Both Filippi and Kiichen- 
 meister* declare that a parasite gets into the mussel 
 or oyster, and its presence there stimulates an active 
 secretion of nacre. 
 
 There are pearls, according to Mobius, which 
 consist of three different systems of layers, like the 
 shells in which they are formed; with this differ- 
 * See their interesting essays in MULLER'S Archiv., 1856. 
 
STUDIES IN ANIMAL LIFE. 127 
 
 ence, that these layers are reversed; in the shell the 
 nacre forms the innermost layer, in the pearl it 
 forms the outermost. Hence the qualities of the 
 pearl depend on the shell, and on the different pro- 
 portions of nacre and carbonate of lime. 
 
 Since we know how pearls are made, may it not 
 be expected that we should learn to make them ? 
 Ever since the days of Linnasus the hope has been 
 entertained, and it is now becoming every day more 
 likely to be realized. Imperfect pearls have been 
 made in abundance. The Chinese have long prac- 
 ticed the art. They simply remove the large fresh- 
 water mussel from the water, insert a foreign sub- 
 stance under the mantle, and in two or three years 
 (if I remember rightly) they take the mussels up 
 again, and find the pearls formed. In this way 
 they make little mother-of-pearl Josses, which are 
 sold for a penny each; and I remember seeing a 
 couple of large shells in the Anatomical Museum at 
 Munich, the whole length of which was occupied by 
 rows of little squab Josses, very comical to behold. 
 I was informed that a copper chain of these deities 
 had been inserted under the mollusk's mantle, and 
 this was the result. 
 
128 STUDIES IN ANIMAL LIFE. 
 
 CHAPTER YI. 
 
 Every Organism a Colony. What is a Paradox ? An Organ is 
 an independent Individual and a dependent one. A Branch 
 of Coral. A Colony of Polypes. The Siphonophora. Uni- 
 versal Dependence. Youthful Aspirings. Our Interest in the 
 Youth of great Men. Genius and Labor. Cuvier's College 
 Life ; his Appearance in Youth ; his Arrival in Paris. Cuvier 
 and Geoffroy St.Hilaire. Causes of Cuvier's Success. One of 
 his early Ambitions. M. le Baron. Omnia vindt labor. Con- 
 clusion. 
 
 THAT an animal organism is made up of several 
 distinct organs, and these the more numerous in 
 proportion to the rank of the animal in the scale of 
 beings, is one of those familiar facts which have 
 their significance concealed from us by familiarity. 
 But it is only necessary to express this fact in lan- 
 guage slightly altered, and to say that an animal 
 organism is made up of several distinct individuals, 
 and our attention is at once arrested. Doubtless it 
 has a paradoxical air to say so ; but Natural His- 
 tory is full of paradoxes ; and you are aware that a 
 paradox is far from being necessarily an absurdity, 
 as some inaccurate writers would lead us to sup- 
 pose ; the word meaning simply " contrary to what 
 is thought" a meaning by no means equivalent to 
 " contrary to what is the fact." It is paradoxical 
 to call an animal an aggregate of individuals, but it 
 
STUDIES IN ANIMAL LIFE. 129 
 
 is so because our thoughts are not very precise on 
 the subject of individuality one of the many ab- 
 stractions which remain extremely vague. To jus- 
 tify this application of the word individual to every 
 distinct organ would be difficult in ordinary speech, 
 but in philosophy there is ample warrant for it. 
 
 An organ, in the physiological sense, is an instru- 
 ment whereby certain functions are performed. In 
 the morphological sense, it arises in a differentiation, 
 or setting apart, of a particular portion of the body 
 for the performance of particular functions a group 
 of cells, instead of being an exact repetition of all 
 the other cells, takes on a difference, and becomes 
 distinguished from the rest as an organ.* 
 
 Combining these two meanings, we have the third 
 or philosophical sense of the word, which indicates 
 that every organ is an individual existence, depend- 
 ent more or less upon other organs for its mainte- 
 nance and activity, yet biologically distinct. I do 
 not mean that the heart will live independent of 
 the body at least not for long, although it does 
 continue to live and manifest its vital activity for 
 some time after the animal's death ; and, in the 
 cold-blooded animals, even after removal from the 
 body. Nor do I mean that the legs of an animal 
 will manifest vivacity after amputation, although 
 even the legs of a man are not dead for some time 
 after amputation; and the parts of some of the 
 lower animals are often vigorously independent. 
 
 * See on this point what was said in our first chapter, p. 22. 
 
 F2 
 
130 STUDIES IN ANIMAL LIFE. 
 
 Thus I have had the long tentacles of a Terebella (a 
 marine worm) living and wriggling for a whole 
 week after amputation.* In speaking of the inde- 
 pendence of an organ, I must be understood to mean 
 a very dependent independence; because, strictly 
 speaking, absolute independence is nowhere to be 
 found ; and, in the case of an organ, it is of course 
 dependent on other organs for the securing, prepar- 
 ing, and distributing of its necessary nutriment. 
 The tentacles of my Terebella could find no nutri- 
 ment, and they perished from the want of it, as the 
 Terebella itself would have perished under like cir- 
 cumstances. The frog's heart now beating on our 
 table with such regular systole and diastole, as if it 
 were pumping the blood through the living animal, 
 gradually uses up all its force ; and since this force 
 is not replaced, the beatings gradually cease. A 
 current of electricity will awaken its activity for a 
 time, but at last every stimulus will fail to elicit a 
 response. The heart will then be dead, and decom- 
 position will begin. 
 
 Dependent, therefore, every organ must be on 
 some other organs. Let us see how it is also inde- 
 pendent ; and for this purpose we glance, as usual, 
 at the simpler forms of life to make the lesson easi- 
 er. Here is a branch of coral, which you know to 
 be in its living state a colony of polypes. Each of 
 these multitudinous polypes is an individual, and 
 each exactly resembles the others. But the whole 
 
 * Seaside Studies, 2d edition, p. 59 sq. 
 
STUDIES IN ANIMAL LIFE. 
 
 131 
 
 colony has one nutritive fluid 
 
 in common. They are all 
 
 actively engaged in securing 
 
 food, and the labors of each 
 
 enrich all. It is animal so- 
 
 cialism of the purest kind 
 
 there are no rich and no poor, 
 
 neither are there any idlers. 
 
 Formerly the coral -branch 
 
 was regarded as one animal 
 
 an individual; and a tree 
 
 was and is commonly regard- 
 
 ed as one plant an individ- 
 
 ual. But no zoologist now 
 
 is unaware of the fact that 
 
 each polype on the branch is 
 
 a distinct individual, in spite 
 
 of its connections with the 
 
 rest; and philosophic bota- 
 
 nists are agreed that the tree is a colony of individ- 
 
 ual plants not one plant. 
 
 Let us pass from the coral to the stem of some 
 other polype, say a Campanularia. Above is the 
 representation of such a stem, of the natural size, 
 and beside it a tiny twig much magnified. You 
 observe the ordinary polype issuing from one of the 
 capsules, and expanding its coronal of tentacles in 
 the water. The food it secures will pass along the 
 digestive tract to each of the other capsules. Un- 
 der the microscope you may watch this oscillation 
 
 (mag . 
 
132 STUDIES IN ANIMAL LIFE. 
 
 of the food. But your eye detects a noticeable dif- 
 ference between this polype in its capsule, and the 
 six semi-transparent masses in the second capsule ; 
 although the two capsules are obviously identical, 
 they are not the same ; a differentiation has taken 
 place. Perhaps you think that six polypes are 
 here crowding into one capsule ? Error ! If you 
 watch with patience, or if you are impatient yet 
 tolerably dexterous, you may press these six mass- 
 es out, and then will observe them swim away, so 
 many tiny jellyfish. Not polypes at all, but jelly- 
 fish, are in this capsule ; and these, in due time, 
 will produce polypes, like that one now waving 
 its tentacles. 
 
 Having made this observation, it will naturally 
 occur to you that the polype stem which bore such 
 different capsules as are represented by these two 
 may perhaps be called a colony, but it is a colony 
 of different individuals. While they have all one 
 skeleton in common, nutrition in common, and res- 
 piration in common, they have at least one differ- 
 entiation, or setting apart for a particular purpose, 
 and that is the reproductive capsule. This is an 
 individual as much as any of the others, but it is an 
 individual that does nothing for the general good ; 
 it takes upon itself the care of the race, and be- 
 comes an " organ" for the community ; the others 
 feed it, and it is absolved from the labor of nutri- 
 tion as much as the arm or the brain of a man are. 
 
 From this case, let us pass to the group of jelly- 
 
STUDIES IN ANIMAL LIFE. 133 
 
 fish, called Siphonophora (siphon-bearers) by natu- 
 ralists, and we shall see this union of very differ- 
 ent individualities into one inseparable colony still 
 more strikingly exhibited : there are distinct indi- 
 viduals to feed the colony, individuals to float it 
 through the water, individuals to act as feelers, and 
 to keep certain parts distended with fluid, and final- 
 ly reproductive individuals. All these are identical 
 in origin, and differ only by slight differentiations.* 
 Here we have obviously an approach to the more 
 complex organism in which various distinct organs 
 perform the several functions, only no one calls the 
 organism a colony. 
 
 The individuals composing one of these Siphono- 
 phora are so manifestly analogous to organs, that 
 their individuality may perhaps be disputed, the 
 more so as they do not live separately. But the 
 gradations of separation are very fine. You would 
 never hesitate to call a bee or an ant an individual, 
 yet no bee or ant could exist if separated from its 
 colony. So great is the " physiological division of 
 labor" which has taken place among these insects, 
 that one can not get food, another can not feed it- 
 self, but it will fight for the community ; another 
 can not work, but it will breed for the community ; 
 another can not breed, but it will work. Each of 
 
 * Compare LEUCKART : Ueber den Polymorpliismus der Individ- 
 ven. GEGENBAUR : Grundzuge der Vergleichende Anatomie ; and 
 HUXLEY'S splendid monograph on the Oceanic Hydrozoa, published 
 by the Ray Society. 
 
134 STUDIES IN ANIMAL LIFE. 
 
 these is little more than separated organs of the 
 great insect organism, as the heart, stomach, and 
 brain are united organs of the human organism. 
 Eemove one of these insects from the community, 
 and it will soon perish, for its life is bound up with 
 the whole. 
 
 And so it is every where ; the dependence is uni- 
 versal : 
 
 " Nothing in this world is single, 
 
 All things, by a law divine, 
 In one another's being mingle." 
 
 We are dependent on the air, the earth, the sun- 
 light, the flowers, the plants, the animals, and all 
 created things, directly or indirectly. Nor is the 
 moral dependence less than the physical. "We can 
 not isolate ourselves if we would. The thoughts 
 of others, the sympathies of others, the needs of 
 others these too make up our life ; without these 
 we should quickly perish. 
 
 It was a dream of the youth Cuvier that a His- 
 tory of Nature might be written which would sys- 
 tematically display this universal interdependence. 
 I know few parts of biography so interesting as 
 those which show us great men in their early aspir- 
 ings, when dreams of achievements vaster than 
 the world has seen fill their souls with energy to 
 achieve the something they do afterward achieve. 
 It is, unhappily, too often but the ambition of youth 
 we have to contemplate; and yet the knowledge 
 that after-life brought with it less of hope, less of 
 
STUDIES IN ANIMAL LIFE. 135 
 
 devotion, and less of generous self-sacrifice, renders 
 these early days doubly interesting. Let the abate- 
 ment of high hopes come when it may, the exist- 
 ence of an aspiration is itself important. I have 
 been lately reading over again the letters of Cuvier 
 when an obscure youth, and they have given me 
 quite a new feeling with regard to him. 
 
 There is a good reason why novels always end 
 with the marriage of the hero and heroine ; our in- 
 terest is always more excited by the struggles than 
 by the results of victory. So long as the lovers 
 are unhappy or apart, and are eager to vanquish 
 obstacles, our sympathy is active; but no sooner 
 are they happy, than we begin to look elsewhere 
 for other stragglers on whom to bestow our inter- 
 est. It is the same with biography. We follow 
 the hero through the early years of struggle with 
 intense interest, and as long as he remains unsuc- 
 cessful, baffled by rivals or neglected by the world, 
 we stand by him and want him to succeed ; but the 
 day after he is recognized by the world our sym- 
 pathy begins to slacken. 
 
 It is this which gives Cuvier's Letters to Pfaff* 
 their charm. I confess that M. le Baron Cuvier, 
 administrator, politician, academician, professor, dic- 
 tator, has always had but a very tepid interest for 
 me, probably because his career early became a, con- 
 tinuous success, and Europe heaped rewards upon 
 
 * Lettres de Georges Cuvier a C. M. Pfaff, 1788-92. Traduites 
 de 1'Allemand, par Louis Marchant, 1858. 
 
136 STUDIES IN ANIMAL LIFE. 
 
 him ; whereas his unsuccessful rival, Geoffrey St. 
 Hilaire, claims my sympathy to the close. If, how- 
 ever, M. le Baron is a somewhat dim figure in my 
 biographical gallery, it is far otherwise with the 
 youth Cuvier as seen in his letters ; and as at this 
 present moment there is nothing under our micro- 
 scope which can seduce us from the pleasant vol- 
 ume, suppose we let our " studies" take a biograph- 
 ical direction? 
 
 " Genius," says Carlyle, "means transcendent ca- 
 pacity for taking trouble, first of all." There are 
 many young gentlemen devoutly persuaded of their 
 own genius, and yet candidly avowing their im- 
 perfect capacity for taking trouble, who will vehe- 
 mently protest against this doctrine. Without dis- 
 cussing it here, let us say that, genius or no genius, 
 success of any value is only to be purchased by im- 
 mense labor : and in science, assuredly, no one will 
 expect success without first paying this price. In 
 Cuvier's history may be seen what " capacity for 
 taking trouble" was required before his success 
 could be achieved ; and this gives these Lettres d 
 Pfaff a moral as well as an interest. 
 
 It was in the Eittersaal of the Academia Carolina 
 of Stuttgardt that Pfaff, the once famous supporter 
 of Yolta, and in 1787 the fellow-student of Cuvier, 
 first became personally acquainted with him. Al- 
 though they had been three years together at the 
 same university, the classification of students there 
 adopted had prevented any personal acquaintance. 
 
STUDIES IN ANIMAL LIFE. 137 
 
 Pupils were admitted at the age of nine, and com- 
 menced their studies with the classic languages. 
 Thence they passed to the philosophical class, and 
 from that they went to one of the four faculties 
 Law, Medicine, Administration, and Military Sci- 
 ence. Each faculty, of course, was kept distinct ; 
 and as Pfaff was studying philosophy at the time 
 Cuvier was occupied with the administrative sci- 
 ences, they never met, the more so as the dormito- 
 ries and hours of recreation were different. The 
 academy was organized on military principles. The 
 three hundred students were divided into six classes, 
 two of which comprised the nobles, and the other 
 four the bourgeoisie. Each of these classes had its 
 own dormitory, and was placed under the charge 
 of a captain, a lieutenant, and two inferior officers. 
 These six classes, in which the students were enter- 
 ed according to their age, size, and time of admis- 
 sion, were kept separate in their recreations as in 
 their studies. But those of the students who par- 
 ticularly distinguished themselves in the public ex- 
 aminations were raised to the rank of knights, and 
 had a dormitory to themselves, besides dining at 
 the same table with the young princes who were 
 then studying at the university. Pfaff and Cuvier 
 were raised to this dignity at the same time, and 
 here commenced their friendship. 
 
 What a charm there is in school friendships, 
 when youth is not less eager to communicate its 
 plans and hopes than to believe in the plans and 
 
138 STUDIES IN ANIMAL LIFE. 
 
 hopes of others ; when studies are pursued in com- 
 mon, opinions frankly interchanged, and the supe- 
 riority of a friend is gladly acknowledged, even be- 
 coming a source of pride, instead of being, as in aft- 
 er years, a thorn in the side of friendship ! This 
 charm was felt by Cuvier and Pfaff, and a small 
 circle of fellow-students who particularly devoted 
 themselves to Natural History. They formed them- 
 selves into a society, of which Cuvier drew up the 
 statutes and became the president. They read mem- 
 oirs, and discussed discoveries with all the gravity 
 of elder societies, and even published, among them- 
 selves, a sort of Comptes Rendus. They made bo- 
 tanical, entomological, and geological excursions ; 
 and, still further to stimulate their zeal, Cuvier in- 
 stituted an Order of Merit, painting himself the me- 
 dallion: it represented a star, with the portrait of 
 Linnaeus in the centre, and between the rays vari- 
 ous treasures of the animal and vegetable world. 
 And do you think these boys were not proud when 
 their president awarded them this medal for some 
 happy observation of a new species, or some well- 
 considered essay on a scientific question ? 
 
 At this period Cuvier's outward appearance was 
 as unlike M. le Baron as the grub is unlike the 
 butterfly. Absorbed in his multifarious studies, 
 he was careless about disguising the want of ele- 
 gance in his aspect. His face was pale, very thin 
 and long, covered with freckles, and encircled by a 
 shock of red hair. His physiognomy was severe 
 
STUDIES IN ANIMAL LIFE. 139 
 
 and melancholy. He never played at any of the 
 boys' games, and seemed as insensible of all that 
 was going on around him as a somnambulist. His 
 eye seemed turned inward; his thoughts moved 
 amid problems and abstractions. Nothing could 
 exceed the insatiable ardor of his intellect. Besides 
 his special administrative studies, he gave himself 
 to Botany, Zoology, Philosophy, Mathematics, and 
 the history of literature. No work was too volu- 
 minous or too heavy for him. He was reading all 
 day long, and a great part of the night. "I re- 
 member well," says Pfaff, " how he used to sit by 
 my bedside going regularly through Bayle's Dic- 
 tionary. Falling asleep over my own book, I used 
 to awake after an hour or two, and find him mo- 
 tionless as a statue, bent over Bayle." It was dur- 
 ing these years that he laid the basis of that exten- 
 sive erudition which distinguished his works in 
 after life, and which is truly remarkable when we 
 reflect that Cuvier was not in the least a bookworm, 
 but was one of the most active workers, drawing his 
 knowledge of details from direct inspection when- 
 ever it was possible, and not from the reports of 
 others. It was here, also, that he preluded to his 
 success as a professor, astonishing his friends and 
 colleagues by the clearness of his exposition, which 
 he rendered still more striking by his wonderful 
 mastery with the pencil. One may safely say that 
 there are few talents which are not available in 
 Natural History ; a talent for drawing is pre-emi- 
 
140 STUDIES IN ANIMAL LIFE. 
 
 nently useful, since it not only enables a man to 
 preserve observations of fugitive appearances, but 
 sharpens his faculty of observation by the exercise 
 it gives. Cuvier's facile pencil was always em- 
 ployed: if he had nothing to draw for his own 
 memoirs or those of his colleagues, he amused him- 
 self with drawing insects as presents to the young 
 ladies of his acquaintance an entomologist's gal- 
 lantry, which never became more sentimental. 
 
 In 1788, that is, in his nineteenth year, Cuvier 
 quitted Stuttgardt, and became tutor in a noble- 
 man's family in Normandy, where he remained till 
 1795, when he was discovered by the Abbe Tessier, 
 who wrote to Parmentier, " I have just found a 
 pearl in the dunghill of Normandy :" to Jussieu. he 
 wrote, " Kemember it was I who gave Delambre to 
 the academy ; in another department this also will 
 be a Delambre." Geoffroy St. Hilaire, already pro- 
 fessor at the Jardin des Plantes, though younger 
 than Cuvier, was shown some of Cuvier's manu- 
 scripts, which filled him with such enthusiasm that 
 he wrote to him, " Come and fill the place of Lin- 
 naeus here ; come and be another legislator of nat- 
 ural history." Cuvier came, and Geoffroy stood 
 aside to let his great rival be seen. 
 
 Goethe, as I have elsewhere remarked, has no- 
 ticed the curious coincidence of the three great zo- 
 ologists successively opening to their rivals the path 
 to distinction : Buffon called Daubenton to aid him ; 
 Daubenton called Geoffroy; and Geoffroy called 
 
STUDIES IN ANIMAL LIFE. 141 
 
 Cuvier. Goethe further notices that there was the 
 same radical opposition in the 'tendencies of Buffon 
 and Daubenton as in those of Geoffroy and Cuvier 
 the opposition of the synthetical and the analyt- 
 ical mind. Yet this opposition did not prevent 
 mutual esteem and lasting regard. Geoffroy and 
 Cuvier were both young, and had in common am- 
 bition, love of science, and the freshness of unform- 
 ed convictions. For, alas ! it is unhappily too true, 
 that just as the free communicativeness of youth 
 gives place to the jealous reserve of manhood, and 
 the youth who would only be too pleased to tell all 
 his thoughts and all his discoveries to a companion 
 would in after years let his dearest friend first see a 
 discovery in an official publication, so likewise, in 
 the early days of immature speculation, before con- 
 victions have crystallized enough to present their 
 sharp angles of opposition, friends may discuss and 
 interchange ideas without temper. Geoffroy and 
 Cuvier knew no jealousy then. In after years it 
 was otherwise. 
 
 Geoffroy had a position he shared it with his 
 friend; he had books and collections they were 
 open to his rival ; he had a lodging in the museum 
 it was shared between them. Daubenton, older 
 and more worldly wise, warned Geoffroy against this 
 zeal in fostering a formidable rival, and one day 
 placed before him a copy of Lafontaine open at the 
 fable of The Bitch and her Neighbor. But Geoffroy 
 was not to be daunted, and probably felt himself 
 
142 STUDIES IN ANIMAL LIFE. 
 
 strong enough to hold his own. And so the two 
 happy, active youths pursued their studies together, 
 wrote memoirs conjointly, discussed, dissected, spec- 
 ulated together, and " never sat down to breakfast 
 without having made a fresh discovery," as Cuvier 
 said truly enough, for to them every step taken was 
 a discovery. 
 
 Cuvier became almost immediately famous on his 
 arrival at Paris, and his career henceforward was 
 one uninterrupted success. Those who wish to 
 gain some insight into the causes of this success 
 should read the letters to Pfaff, which indicate the 
 passionate patience of his studies during the years 
 1788-1795, passed in obscurity on the Norman 
 coast. Every animal he can lay hands on is dis- 
 sected with the greatest care, and drawings are 
 made of every detail of interest. Every work that 
 is published of any note in his way is read, ana- 
 lyzed, and commented on. Lavoisier's new system 
 of chemistry finds in him an ardent disciple. Kiel- 
 meyer's lectures open new vistas to him. The mar- 
 vels of marine life, in those days so little thought 
 of, he studies with persevering minuteness and with 
 admirable success. He dissects the cuttlefish, and 
 makes his drawings of it with its own ink. He 
 notes minute characters with the patience of a spe- 
 cies-monger, whose sole ambition is to affix his 
 name to some trifling variation of a common form, 
 yet with this minuteness of detail he unites the large- 
 ness of view necessary to a comparative anatomist. 
 
STUDIES IN AN 
 
 " Your reflections on the diffe 
 mals and plants," he writes, t; in the passage to 
 which I previously referred, will be the more agree- 
 able to me, because I am at present working out a 
 new plan of a general natural history. I think we 
 ought carefully to seek out the relation of all exist- 
 ences with the rest of nature, and, above all, to show 
 their part in the economy of the great All. In this 
 work I should desire that the investigator should 
 start from the simplest things, such as air and wa- 
 ter, and after having spoken of their influence on 
 the whole, he should pass gradually to the com- 
 pound minerals, from these to plants, and so on; 
 and that at each stage he should ascertain the exact 
 degree of composition, or, which is the same thing, 
 the number of properties it presents over and above 
 those of the preceding stage, the necessary effects 
 of these properties, and their usefulness in creation. 
 Such a work is yet to be executed. The two works 
 of Aristotle, De Historia Animalium, and De Parti- 
 lus Animalium, which I admire more each time that 
 I read them, contain a part of what I desire, name- 
 ly, the comparison of species, and many of the gen- 
 eral results. It is, indeed, the first scientific essay 
 at a natural history. For this reason it is necessa- 
 rily incomplete, contains many inaccuracies, and is 
 too far removed from a knowledge of physical laws." 
 He passes on from Aristotle to Pliny, Theophrastus, 
 Dioscorides, Aldovrandus, Gesner, Gaspar Bauhin, 
 
144 STUDIES IN ANIMAL LIFE. 
 
 and Kay, rapidly sketching the history of natural 
 history as a science, and concluding with this criti- 
 cism on these attempts at a nomenclature which 
 neglected real science: " These are the dictionaries 
 of natural history ; but when will the language be 
 spoken ?" 
 
 No one who reads these letters attentively will 
 be surprised at the young Cuvier's taking eminent 
 rank among the men of science in France ; and 
 Pfaff, on arriving in Paris six years afterward, 
 found his old fellow-student had become " a per- 
 sonage." The change in Cuvier's appearance was 
 very striking. He was then at his maturity, and 
 might pass for a handsome man. His shock of red 
 hair was now cut and trimmed in Parisian style; 
 his countenance beamed with health and satisfac- 
 tion ; his expression was lively and engaging ; and, 
 although the slight tinge of melancholy which was 
 natural to him had not wholly disappeared, yet the 
 fire and vivacity of his genius overcame it. His 
 dress was that of the fashion of the day, not with- 
 out a little affectation. Yet his life was simple, 
 and wholly devoted to science. He had a lodg- 
 ing in the Jardin des Plantes, and was waited on 
 by an old housekeeper, like any other simple pro- 
 fessor. 
 
 On Pfaff 's subsequent visit things were changed. 
 Instead of the old housekeeper, the door was open- 
 ed by a lackey in grand livery. Instead of asking 
 
STUDIES IN ANIMAL LIFE. 145 
 
 for " Citizen Cuvier," lie inquired for Monsieur Cu- 
 vier ; whereupon the lackey politely asked whether 
 he wished to see M. le Baron Cuvier, or M. Frede- 
 ric, his brother ? "I soon found where I was,'' 
 continues Pfaff. " It was the baron, separated from 
 me by that immense interval of thirty years, and by 
 those high dignities which an empire offers to the 
 ambition of men." He found the baron almost 
 exclusively interested in politics, and scarcely giv- 
 ing a thought to science. The " preparations" and 
 "injections" which Pfaff had brought with him 
 from Germany as a present to Cuvier were scarce- 
 ly looked at, and were set aside with an indifferent 
 " that's good," and " very fine ;" much to Pfaff's 
 distress, who doubtless thought the fate of the Mar- 
 tignac ministry an extremely small subject of in- 
 terest compared with these injections of the lym- 
 phatics. 
 
 But it is not my purpose to paint Cuvier in his 
 later years. It is to the studies of his youth that I 
 would call your attention, to read there, once again, 
 the important lesson that nothing of any solid value 
 can be achieved without entire devotion. Nothing 
 is earned without sweat of the brow. Even the 
 artist must labor intensely. What is called "in- 
 spiration" will create no works, but only irradiate 
 works with felicitous flashes ; and even inspiration 
 mostly comes in moments of exaltation produced 
 by intense work of the mind. In science, incessant 
 
146 STUDIES IN ANIMAL LIFE. 
 
 and enlightened labor is necessary, even to the 
 smallest success. Labor is not all ; but without it 
 genius is nothing. 
 
 With this homily, dear reader, may be closed our 
 FIRST SERIES of Studies ; to be resumed hereafter, 
 let me hope, with as much willingness on your part 
 as desire to interest you on mine. 
 
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