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The following diagrams illustrate the method: L'exemplaire filmd fut reproduit grdce d la g^ndrositd de I'dtablissement prdteur suivant : La bibliothdque des Archives publiques du Canada Les cartes ou les planches trop grandes pour dtre reproduites en un seul clich6 sont filmdes d partir de Tangle supdrieure gauche, de gauche d droite et de haut en bas, en prenant le nombre d'images n^cessaire. Le diagramme suivant illustre la m^thode : 1 2 3 1 2 3 4 5 6 ORIGIN AND HISTORY OF LIFE ON OUR PLANET. AN ADDRESS BY VICE-PRESIDENT J. W. DAWSON, jticKoiti': Till-: AMERK^AN ASSOCIATION KOIt TIIK ADVANCEMENT OF SCIENCE, AT DETROIT, MICHIGAN, AUGUST, 1875. MONTREAL : W . I) R Y 8 D A L K A CO. 1875. >?.'r. # ■(^ ' T CANADA PUBLIC ARCHIVES ARCHIVES PUBLIQUES \ OBIQIN AND HI8T0BY OF LIFE ON OUB PLANET. AN ADDKESS BT VICE-PRESIDENT J. W. DAWSON, BEFORE THE AMERICAN ASSOCIATIOIS^ FOB THE ADYANCEMENT OF SCIENCE, AT DETROIT, MICHIGAN, AUGUST, 1875. MONTREAL : W. DRYSDALE & CO. 1875. (') PRINTED AT THE SALEM PRESS, Salem, Mass. b:<^'H ADDRESS OF J. W. DAWSON . Of thtf leaders in Natural Science, the guides and teachers of some of us now becoming gray, who have in the past year been stricken by der "rom the roll of workers here, and have en- tered into the li ^een world, two rise before me with special vividness on the r - ent occasion : — Lyell, our greatest geological thinker, the classifier of the Tertiary rocks, the summer up of the evidence on the antiquity of man ; but above all the founder of that school of geology which explains the past changes of our globe by those at present in progress ; and Logan, the careful and acute stratigraphist, the explorer and establisher of the Lauren- tian system, and the first to announce the presence of fossil re- mains in those most ancient rocks. What these men did and what dying they left undone, alike invite us to the consideration of the present standpoint of Geological science, the results it has achieved and the objects yet to be attained ; and I propose ac- cordingly to select a small portion of this vast field and to oflTer to you a few thoughts in relation to it, rather desultory and sug- gestive however, than in any respect final. I shall therefore ask your attention for a short time to the question — "What do we know of the origin and history of life on our planet?" This great question, confessedly accompanied with many difficul- (8) ■'§"'" VICE PKE8IDENT 8 ADDRESS. ties and still waiting for its full solution, has points of intense interest both for the Geologist and the Biologist. In treating of it here, it will be well, however meagre the result, to divest it of merely speculative views, and to present as far as possible the actual facts in our possession, and the conclusions to which they seem to point. "If," says that greatest of uniformitarian geologists, who has so recently passed away, "the past duration of the earth be finite, then the aggregate of geological epochs, however numerous, must constitute a mere moment of the past, a mere infinitesimal portion of eternity." Yet to our limited vision, the origin of life fades away in the almost illimitable depths of past time, and we are ready to despair of ever reaching, by any process of discovery, to its first steps of progress. At what time did life begin? In what form did dead matter first assume or receive those mj'sterioifs functions of growth, reproduction and sensation? Only when we picture to ourselves an absolutely lifeless world, destitute of any germ of life or organization, can we realize the magnitude of these questions, and perceive how necessary it is to limit their scope if we would hope for any satisfactory answer. I shall here dismiss altogether that form in which these ques- tions present themselves to the biologist, when he experiments as to the evolution of living forms from dead liquids or solids — an unsolved problem of spontaneous generation which might alone occupy the whole time of this Section. Nor shall I enter on the vast field of discussion as to modern animals and plants opened up by Darwin and others. I shall confine myself altogether to that historical or paloeontological aspect in which life presents itself when we study the fossil remains entombed in the sediments of the earth's crust, and which will enable me at least to show why some students of fossils hesitate to give in their adhesion to any of the current notions as to the origin of species. I may also explain that I shall avoid, as far as possible, the use of the term evolution, as this has recently been employed in so manj' senses as to have become nearly useless for any scientific purpose, and that when I speak of creation of species, the term is to be understood not in the arbitrary sense forced on it by some modern writers, but as indicating the continuous introduction of new forms of life under definite laws, but bj' a power not emanating from within themselves, nor from the inanimate nature surrounding them. ' VICE president's address. If we were to follow the guidance of those curious analogies which present themselves when we consider the growth of the in- dividual plant or animal from the spore or the ovum, and the de- velopment of vegetable and animal life in geological time — analo- gies which, however, it must be borne in mind can have no scien- tific value whatever, inasmuch as that similarity of conditions which can alone give force to reasoning from analogy in matters of sci- ence, is wholly wanting — we should expect to find in the oldest rocks embryonic forms alone, but of course embryonic forms suited to exist and reproduce themselves independently. I need not say to palaeontologists that this is not what we actu- ally find in the primordial rociis. I need but to remind them of the early and remarkable development of such forms as the Trilo- bitos, the Lingulidae and the Pteropods, all of them highly com- plex and specialized types, and remote from the embryonic stages of the groups to which they severally belong. In the case of the Trilobites, I need but refer to the beautiful symmetry of their parts both transversely and longitudinally, their division into distinct regions, the complexity of their muscular and nervous systems, their highly complex visual organs, the superficial ornamentation and microscopic structure of their crusts, tiieir advanced position among Crustaceans, indicated by their strong affinities with the Isopods. All these chtiracters give them an aspect far from em- bryonic, while, as Barrande has pointed out, this advanced po- sition of the group has its significance greatly strengthened by the fact that in early primordial times we have to deal not with one species but with a vast and highly diflferentiated group, embr tcing forms of many and varied subordinate types. As we shall see, these and other earl}' animals may be regarded as of generalized types but not as embryonic. Here then meets us at the outset the fact that in as far as the great groups of annulose and mol- luscous anim.als are concerned, we can trace these back no further than in a period in which they appear already highlj' advanced, much specialized and represented by many diverse forms. Either therefore these great groups came in on this high initial plane, or we have scarcely reached half way back in the life history of our planet. We have here, however, by this one consideration attained at once to two great and dominant laws regulating the history of life. First, the law of continuity, whereby new forms come in VICE president's address. successive!}', throughout geological time, though as we shall see with periods of greater aud less freqjiency. Secondly, the law of specialization of types, whereby generalized forms are succeeded by those more special, and this probably connected with the grow- ing specialization of the inorganic world. It is this second law which causes the parallelism between the history of successive species and that of the embryo. But there are great masses of strata known as Lower Cambrian, Huronian, Laurentian, which have made as yet few revelations as to the life which may have existed at the time of their deposition. In these rocks we know the problematical Aspklella of Billings from Newfoundland, the worm-burrows or Scolithus-like objects which occur in the Pre-silurian rocks of Madoc, the Eozoon Bava- ricum of Gurabcl, and the Eozoon Canadense, first made known by Logan, in the Laurentian of Canada. The first of these names represents a creature that may have been a moUusk, allied to Pa- tella, or some obscure form of crustacean. The cylindrical holes called worm-burrows, are of course quite uncertain in their refer- ence. They may represent marine worms in no respect different from those now swarming on our shores, or sponges, or corals, or sea-weed&. In any case they afford little help in explaining the teeming life of the primordial seas, and we caji only hope that the vast thickness of sediments which has afforded these few traces of life may prove more fertile in the future. One slender beam of light in the darkness is, however, afforded by the Eozoon Bava- ricum of G umbel. If truly a fossil, this creature is closely con- nected with the still older Eozoon of the Laurentian. It there- fore points backward to what is to us the dawn of life, but has no close link of connection with the succeeding fauna. On the other hand Aspidella and ScoUthvs may be held, if obscurely, to point forward. Thus the Huronian and early Cambrian become a pe- riod of transition from tjje Protozoa of the Laurentian to the higher marine life that succeeds — a passage to be more fully ex- plained perhaps, and its great gaps filled by future discoveriae ; but which may, as in some later periods, be complicated with a contemporaneous transition from oceanic to shallow-water condi- tions in the localities open to exploration. It will be observed that 1 take for granted the animal nature of Eozoon. If we reject this, we stand face to face with the bare, bald mystery of the abrupt manifestation of the Primordial fauna, VICE president's address. without even so much of preparation as may be supposed to arise from the previous appearance of Protozoa. How then stand the facts as to the Proto-foraminifer? In an- swering this question, we should, I think, endeavor to divest ourselves of certain prejudices, and to give due weiglit to some probabilities and analogies which may in one way or another sway our opinion. First, we must be prepared to find that those old crystalline rocks which we call Laurentian, have no real affinity with intru- sive granites and other igneous masses, but are most nearly allied to modern sedimentary deposi^^^s. That the original chemical char- acter of some of these ancient sediments may have differed to some extent from that of more modern sediments I do not doubt. Yet it is true that the more common of them, as the gneisses, diorites and mica-schists, consist of precisely the same elements which now appear in modern clays and sands, and that where local alteration has affected more modern rocks, we see these passing by insensible gradations into similar metamorphic beds. Farther when the old crystalline jocks are subjected to subaerial disinte- gration, they resolve themselves again into the most common sedi- mentary materials. Another consideration here is the unequal manner in which sediments become altered according to their composition, and to the extent to which they are permeable by heated waters and vapors. For this reason, contiguous beds of rock will often be seen to differ very much in the degree of their alteration. Farther, some beds, and more especially limestones, continue to retain traces of organic structure long after these have perished from neighboring beds of different chemical composition. More especially when, in limestone, the cavities and pores of the fossils have been penetrated with other mineral matter, it would appear that nothing short of actual fusion will serve to obliterate them. Again, microscopic structures are often well preserved when the external forms have been lost, or are completely inseparable from the matrix, and in the present state of microscopical science there is little danger that in such specimens any experienced microsco- pist will fail to perceive the difference between organic and crys- talline structures. Having freed ourselves from misconceptions of these kinds, we may next turn to certain presumptions established by the consti- 8 VICE president's address. tution of the Laurentian rocks, and the minerals contained in them. The limestones of the Laurentian system are of great thickness and of vast geographical extent. Sir W. E. Logan has traced and measured three principal bands of these limestones, ranging in thickness from 60 to 1,500 feet, and traceable continuously in one district of Canada for more than one hundred miles, while their actual horizontal area must be enormously greater than this distance would indicate. These limestones are also associated with gneissose and schistose beds, exactly in the same way in which Palaiozoic limestones are associated with sandstones and shales ; and some of them are ordinary limestones, while others are more or less doloraitic, in which also they resemble the palaeo- zoic limestones. Every geologist knows that the beds which in the succeeding geological periods are the representatives of these Laurentian limestones, are not only fossiliferons, but largely com- posed of the debris of oceanic organisms, and that it is to the purer and more crystalline beds that this statement most fully ap- plies. May we not reasonably infer that the great Laurentian limestones are of similar origin. One feature of these beds which has sometimes received a very diflPerent interpretation, I would here place in this connection. It is the association of Hydrous Silicates, and especially of Serpen- tine and Loganite, with the limestones, an association not universal but by no means uncommon in the Laurentian, and which may now be affirmed to occur throughout the whole s\mea of marine organic limestones, up to tlie chalky foraminifera' n^ud now accu- mulating in the depths of the ocean. It is true that the silicates found in different formations differ somewhat in composition, but Dr. Sterry Hunt has shown that the Serpentines, Jollite, Loganite and the various Glauconites constitute a single series, whose mem- bers graduate into each oth^r, and some of the modern Glauco- nites are not essentially distinct from the most ancient Serpentine. This association is not accidental, it arises in the first place from the facility afforded for the combination of Silica with bases, arising from the presence of organic matter in the sea-bottom, and secondly from the abundance of soluble Silica in the hard parts of Diatoms, Radiolarians and Sponges, while these form the chief food of animals building their own skeletons of Carbonate of Lime, and consequently having no need of Silica. In this in VICE PRESIDENT S ADDRESS. 9 point of view the Hydrous Silicates may be regarded as a sort of coprolrtic matter, rejected by Foraraiaifera and other humble ma- rine animals having calcareous skelftons. I hoi ^ therefore, that the association of Serpentine and Loganite with the Laurentian limestones affords an additional reason for regarding them as organic, while it also explains the favorable conditions in which Foraminifera exist for the permanent preservation of the struc- tures of their tests. But again, there are vast quantities of Carbon in *hese lime- stones and the associated beds. The quantity of carbon in some large regions of the Lower Laurentian in Canada, is, as I have elsewhere shown, comparable with that in similar thicknesses of the Carboniferous system. But what geologist refers the carbon of the Palaeozoic rocks to any other than an organic origin. True it is that this carbon of the Laurentian is in the state of graphite and destitute of organic structure ; but this applies i;0 similar material in other altered rocks, for example, to the graphitic shales of the Silurian of Eastern Canada and to the coal of Rhode Island. Lastly, ought we not to attach some value to that generalization of Dr. Sterry Hunt, which affirms that the grand agent in the reduction and solution of the Peroxide of Iron has been organic matter. In this case what incalculable quantities of perished carbonaceous matter must be represented by the great beds of Magnetite .in the Laurentian. If, then, it is not unreasonable to believe that the Laurentian limestonas may be of organic origin, the next question that occurs relates to the state of preservation in which the remains of such supposed organisms may ^>ccur. It would be conceivable that the process of cr3'stalline rearrangement of particles might have pro- ceeded so far as entirely to obliterate all traces of organic form or structure ; but judging from other cases of altered limestones, this would be scarcely likely. In such limestones it is true, the fossils are often so obscure as to make little appearance on a fresh frac- ture of the stone, but they may present themselves distinctly on the weathered surfaces, in consequence of some difference either in resisting power or hardness, between the fossil and the matrix. In some cases also they can readily be developed by the action of an acid, and still more frequently their microscopic textures re- main when the external fo'-ms are entirely concealed. There are HM ■aga 10 VICE president's address. few crystalline msubles, once fossillferoiis, that do not exhibit in- dications of their true nature in one or other of these ways. It was precisely in the ways above indicated that Eozoon Cana- dense was first brought to light. The casts of its flattened cham- bers filled with Serpentine, Loganite or Pyroxene, project from the weathered surfaces of the Laurentian limestones, exactly as silici- fied StromatoporcB do in the Silurian. Such specimens, collrcted by the explorers of the Canadian Survey, first gave the idea that there were fossils in these ancient rocks, and the microscope soon confirmed the indications afforded by external form, and demon- strated the place of the organism in the animal kingdom. Into the description of the forms and structures of Eozoon it "would be out of place to enter here. The details of these maj' be found in publications specially devoted to its descripLion. I would merely insist on the entire conformity of the microscopic struc- tures as I have myself examined and described them, and as they have been farther scrutinized by Dr. Carpenter and others best fitted to judge, with those of the calcareous tests of Foramlnifera, and especially of the Numrauline group, and on the harmony of these structures with what the general considerations already re- ferred to would lead us to expect. It is, however appropriate to oar present subject, to inquire as to the position of Eozoon in the scale of animal existence, and its possible relations to preceding or succeeding types of life. "With reference to these questions, it is obvious that we can predi- cate nothing as to the relation of our proto-foraminifers to the varied life of the Primordial or to any other group of animals than its own. We do not know that Eozoon was the only animal of its time. It may be merely a creature characteristic, like some of its successors, of certain habitats in the deep sea. Foraminifera h&va existed throughout the whole of geological lime ; but we have no positive evidence that any animal of this class has ever been transmuted into any other kind of creature. These consid- erations oblige us to restrict our inquiries to the relation of Eozoon to other forms of Foraminiferal life. We may the more excusably take this ground since even Ileeckel, in his gastrula theory, has so strenuously maintained the distinctness of the Pro- tozoa from all higher forms of life. Viewed in this way, we find that the proto-foraminifer was the greatest of all in point of mag- nitude, one of the most complex in regard to structure, compre- «i VICE president's address. 11 hensive in type, as connecting the groups now recognized as the Nummiilines and the Rotalines, and if inferior in anything only in less definiteness of habit of growth, a character in which it is paralleled by the sponges and other groups of higher rank. Thus if Eozoon was really the beginning of Foraminifers, this, like other groups in later times, appeared at first in one of its greatest and best forms, and its geological history consists largely in a gradual deposition from its high place as other and higher types little by little took its place ; for degradation as well as elevation, belongs to the plan of nature. Eozoon here brings under our notice another phase of a creative law, which is corroborated by other forms of life in the succeeding periods. It is this. New types do not usually appear in their lowest forms, but in some- what high if generalized species. The fact that Foraminifera, al- lied to Eozoon, have continued to exist ever since, introduces us to still another, namely, that though species and individuals die, any large group once introduced is very permanent, and may con- tinue to be represented for the remainder of geological time. But let us leave for the present the somewhat isolated case of Eozoon, and the few scattered forms of the Huronian and early Cambrian life, and go on further to the Primordial fauna. This is graphically presentc 1 to us in the sections at St. David's in South Wales, as described by Ilicks. Here we find a nucleus of ancient rocks supposed to be Laurentian, though in mineral character more nearly akin to our Huronian, but which have hitherto af- forded no trace of fossils. Resting unconformably on these is a series of partiall}^ altered rocks, regarded as Lower Cambrian, and also destitute of organic remains. These have a thickness of al- most 1,000 feet, and they are succeeded by 3,000 feet more of similar rocks, still classed as Lower Cambrian, but which have afforded fossils. The lowest bed which contains indications of life is a red shale, perhaps a deep-sea bed, and possibly itself of organic origin, by that strange process of decomposition or dis- solution of foraminiferal ooze, described by Dr. Wyville Thomson as occurring in the South Pacific. The species are two LingulelloB, a Discina and a Leperdltia. Supposing these to be all, it is re- markable that we have no Protozoa or Corals or Echinoderms, and that the types of Brachiopods and Crustaceans are of compara- tively modern affinities. Passing upward through another 1,000 feet of barren sandstone, we reach a zone in which no less than w 12 VICE president's address. i'. five genera of Trilobites are found, along with Pteropods and a sponge. Thus it is that life comes in at the base of the Cambrian in Wales, and it may be regarded as a fair specimen of the facts as the}- appear in the earlier fossiliferous beds succeeding the Laurentian. Taking the first of these groups of fossils, we may recognizvi in the Leperditia an oftracod Crustacean closely allied to forms still living in the seas and fresh waters. The Lingulellce, whether we regard them as molluscoids, or with ir colleague, Professor Morse, as singularly specij^lized worms, represent a pe- culiar and distinct t^pe, handed down, through all the vicissitudes of the geological ages, to the present day. Had the Primordial life begun with species altogether inscrutable and unexampled in succeeding ages, this would no doubt have been mysterious ; but next to this is the mystery of the oldest forms of life being also among the newest. One great fact shines here with the clearness of noon-day. Whatever the origin of these creatures, they repre- sent families which have endured till now in the struggle for ex- istence without either elevation or degradation. Here again we may formulate another creative law. In every great group there are some forms much more capable of long continuance than oth- ers. Lingula among the Brachiopods is a marked instance. But when, with Hicks, we surmount the mass of barren beds overlying these remains, which from its unfossiliferous char- acter is probably a somewhat rapid deposit of arctic mud, like that which in all geological time has constituted the rough filling of our continental formations, and have suddenly sprung upon us five genera of Trilobites, including the fewest-jointed and most many-jointed, the smallest and the largest of their race, our as- tonishment must increase, till we recognize the fact that we are now in the presence of another great law of creation, which pro- vides that every new type shall be rapidly extended to the ex- treme limits of its power of adaptation. Before considering these laws, however, let us in imagination transfer ourselves back to the Primordial age, and suppose that we have in our hands a living Plutonia, recently taken from the sea, flapping vigorously its great tail, and full of life and energy ; an animal larger and- heavier than the modern king-crab of our shores, furnished with all that complexity of external parts for which the crustaceans are so remarkable, no doubt with instincts and feelings and modes of action as pronounced as those of its VICE president's address. 18 modern allies, and if Woodward's views are correct, on a higher plane of rank than the king-crab itself, inasmuch as it is a com- posite type connecting Limuli with Isopods. "We have obviously here in the appearance of this great crustacean, a repetition of the facts which we met with in Eozoon ; but how vast the interval between them in geological time, and in zoological rank. Stand- ing in the presence of this testimony, I thiiik it is only right to say that we possess no causal solution of the appearance of these early forms of life ; but in tracing th^m and their successors up- ward through the succeeding ages, we may hope at least to reach some expressions of the laws of their succession, in possession of which we may return to attack the mystery of their origin. First, it must strike every observer that there is a great same- ness of plan throughout the whole history of marine invertebrate life. If we turn over the pages of an illustrated text-book of geology, or examine the cases or drawers of a collection of fossils, we shall find extending through every succeeding formation, rep- resentative forms of crustaceans, mollusks, corals, etc., in such a manner as to indicate that in each successive period there has been a reproduction of the same type with modifications ; and if the series is not continuous, this appears to be due rather to abrupt ph3'sical changes ; since sometimes where two formations pass into each Other, we find a gradual change in the fossils by the dropping out and introduction of species one by one. Thus in the whole of the great Palaeozoic Period, both in its Fauna and Flora, we have a continuity and similarity of a most marked character. It is evident that there is presented to us in this similarity of the forms of successive faunas and floras, a phenomenon which deserves very careful sifting as to the question of identity or di- versity of species. The data for its compi'ehension must be ob- tained by careful study of the series of closely allied forms occur- ring in successive formations, and our great and undisturbed Palaeozoic areas in America, as Nicholson has recently pointed out, seem to give special facilities for this, which should be worked, not in the direction of constituting new species for every slightly divergent form, but in striving to group these forms into large spe- cific types. The Rhynchonellae of the type of R. plena, the Orthids of the type of 0. testudinaria, the Strophomenae of the types of S. alternata and S. rhomboidalis, the Atrypae of the type of A. u VICE PRESIDENT S ADDRESS. reticularis, furnish cases in point among the Brachiopods. There is nothing to preclude the supposition that some of these groups are really specific types, with numerous race modifications. My own provisional conclusion, based on the study of Palaeozoic plants, is that the general law will be found to be the existence of distinct specific types, independent of each other, but liable in geological time to a great many modifications, which have often been re- garded as distinct species. While this unity of successive faunae at first sight presents an appearance of hereditary succession, it loses much of this char- acter when we consider the number of new types introduced with- out apparent predecessors, the necessity that there should be simi- larity of type in successive faunae on any hypothesis of a contin- uous plan ; and above all, the fact that the recurrence of repre- sentative species or races in large proportion marks times of decadence rather than of expansion in the types to which they belong. To turn to another period, this is very manifest in that singular resemblance which obtains between the modern mammals of South America and Australia, and their immediate fossil prede- cessors — the phenomenon being here manifestly that of decadence of large and abundant species into a few depauperated represent- atives. This will be fouq^l to be a very general law, elevation being accompanied by the abrupt appearance of new types and decadence by the apparent continuation of old species, or modifi- cations of them. This resemblance with difference in successive faunas also con- nects itself very directly with the successive elevations and de- pressions of our continental plateaus in geological time. Every great Palaeozoic limestone, for example, indicates a depression with succeeding elevation. On each elevation marine animals were driven back into the ocean, and on each depression swarmed in over the land, reinforced by new species, either then introduced or derived by migration from other localities. In like manner ou every depression, land plants and animals were driven in upon insular areas, and on reelevation again spread themselves widely. Now I think it will be found to be a law here that periods of ex- pansion were eminently those of introduction of new specific types, and periods of contraction those of extinction, and also of continuance of old types under new varietal forms. It must also be borne in mind that all the leading types of in- t VICE president's address. 15 Ill- vertebrate life were early introduced, that change within these was necessarily limited, and that elevation could take place mainly by the introduction of the vertebrate orders. So in plants, Cryp- togams early attained their maximum as well as Gymnosperms, and elevation occurred in the introduction of Phienogams, and this not piecemeal, but as we shall see in the sequel, in great force at once. Another allied fact is the simultaneous appearance of like types of life in one and the same geological period, over widely separ- ated regions of the earth's surface. This strikes us especially in the comparatively simple and homogeneous life-dynasties of the Palaeozoic, when for example we find the same types of Silurian Graptolites, Trilobites and Brachiopods appearing simultaneously in Australia, America and Europe. Perhaps in no department is it more impressive than in the introduction in the Devonian and Carboniferous Ages of that grand cryptogamous and gymnosper- mous flora which ranges from Brazil to Spitzbergen, and from Aus- tralia to Scotland, accompanied in all by the same groups of ma- rine invertebrates. Such facts may depend either on that long life of specific types which gives them ample time to spread to all possible habitats, before their extinction, or on some general law whereby the conditions suitable to similar types of life emerge at one time in all parts of the world. Both causes may be influen- tial, as the one does not exclude the other, and there is reason to believe that both are natural facts. Should it be ultimately proved that species allied and representative, but distinct in origin, come into being simultaneously everywhere, we shall arrive at one of the laws of creation, and one probably connected with the gradual change of the physical conditions of the world. Another general truth, obvious from the facts which have been already collected, is the periodicity of introduction of species. They come in by bursts or flood-tides at particular points of time, while these great life-waves are followed and preceded by times of ebb in which little that is new is being produced. We labor in our Investigation of this matter under the disadvantage that the modern period is evidently one of the times of pause in the crea- tive work. Had our time been that of the early Tertiary or early Mesozoic, our views as to the question of origin of species might have been very different. It is a striking fact, and in illustration of this, that since the glacial age no new species of mammal can . If' 16 VICE president's address. be proved to have originated on our continents, while a great num- ber of large and conspicuous forms have disappeared. It is pos- sible that the proximate or secondary causes of the ebb and flow of life production maj' be in part at least physical, but other and more important efficient causes may be behind these. In any case these undulations in the history of life are in harmony with much that we see in other departments of nature. It results from the above and the immediately preceding state- ment, that specific and generic types enter on the stage in great force and gradually taper off toward extinction. They should so appear in the geological diagrams made to illustrate the succession of life. This applies even to those forms of life which come in with fewest species and under the most humble guise. What a remarkable swarming, for example, there must have been of Mar- supial Mammals in the early Mesozoic, and in the Coal formation the only known Pulmonates, four in number, belong to as many generic types. I have already referred to the permanence of species in geolog- ical time. I may now place this in connection with the law of rapid origination and more or less continuous transmission of va- rietal forms. I may, perhaps, best bring this before you in con- nection with a group of species with which I am very familiar, that which came into our seas at the beginning of the Glacial age and still exists. With regard to their permanence, it can be affirmed that the shells now elevated in Wales to 1,200, and in Canada to 600 feet above the sea, and which lived before the last great revolution of our continents, a period vastly remote as compared with human history, differ in no tittle from their mod- ern successors after thousc^nds or tens of thousands of genera- tions. It can also be affirmed that the more variable species ap- pear under precisely the same varietal forms then as now, though these varieties have changed much in their local distribution. The real import of these statements, which might also be made with regard to other groups, well known to paleontologists, is of so great significance that it can be realized only after we have thought of the vast time and numerous changes through which these humble creatures have survived. I may call in evidence here a familiar New England animal, the common sand clam, Mya arenaria, and its relative Mya ^wwca^a, which now inhabit together all the northern seas ; for the Pacific specimens, from Japan and VICE puesidknt's address. 17 The with of so have ^hich :lence Mya :ether and California, tlioiicjh diflerently namod, aro undoubtorlly the same. Mya trnncatn appears in P^iirope in the Coralline Crag, and was followed by 3f. arenaria in the Red Cra<>:. Both shells occnr in the Pleistocene of America, and their several varietal forms had al- ready developed themselves in the Crao;, and remnin the same to- day ; so that tiiese huml)le niollnsks, littoral in their habits, and subjected to a <;reat variety of conditions, have continued perhaps for one or two thousand centuries to construct their shells prc- cisel}' as at present. Nor are there any indications of a transition between the two species. I might make similar statements with regard to the Astartes, Buccinums and Tellinai of the drift, and couhl illustrate them by extensive series of specimens from my own collections. Another curious illustration is that presented by the Tertiary and modern fannse of some oceanic islands far separated from the continents. In Madeira and Porto Santo, for example, according to Lyell, we have fifty-six species of land shells in the former, and forty-two in tl;e latter, only twelve being common to the twcS^ though these islands are only thirty miles apart. Now in the Pli- ocene strata of INIadeira nnd Porto Santo we tind thirty-six species in the former, and thirty-live in the latter, of which only eight per cent, are extinct, and j'et only eight are common to the two islands. Further there seem to bo no transitional forms connect- ing the species, and of some of them the same varieties existed in the Pliocene as now. The main dilference in time is the extinc- tion of some species and the introduction of others without known connecting links, and the fact that some species, plentiful in the Pliocene, are rare now and vice versa. All these shells differ from those of modern Europe, but some of them are allied to Miocene species of that continent. Here we have a case of continued ex- istence of the same forms, and in circumstances which the more we think of them the more do they defy all our existing theories as to specific origins. Perhaps some of the most remarkable facts in connection with the permanence of varietal forms of species, are those furnished by that magnificent fiora which burst in all its majesty on the American continent in the Cretaceous period, ar.d still survives among us even in some of its specific types. I say survives; for we have but a remnant of its forms living, and comparatively' little that is new has probably been added since. The confusion which A. A. A. 8. VOL. XXIV. B, (2) 18 VICE PHKSIDKNT S ADDKKSS. 4 ii"! I obtfiins as to llio nge of this flora, niifl tlie discussions in which Newbeny, Ilcor, Lesqucrcnx and recently INIr. G. M. Dawson, have taken part, obvionsl^' arise, as the hitter has I thinii conclusively shown, from the fact that this modern flora was in its enrlier times contem[)orary with Cretaceous animals, and survived the ojradual change from the animal life of the Cretaceous down to that of the Eocene and even of the Miocene. In a collection of these plants from what may be termed beds of transition from the Cretaceous to the Tertiary, I find among other modern species two recent ferns most curiously associated. One is the connnon Onoclea sen- sibih's^ found now very widely over North America, and which in so-called Miocene times lived in Europe also. The other is Da- vallia tennifoJia of Eastern Asia — a fern not now even generically represented in North Americn, but still abundant on the other side of the Pacific. These little ferns are thus probably older than the Rocky Mountains and the Himalayas, and reach back to a time when the Mesozoic Dinosaurs were becoming extinct and the earliest Placental mammals being introduced. Shall we say that these ferns and along with them our two species of American Hazel and many other familiar plants, have propagated themselves unchanged for half a million of years? Take from the western Mesozoic a contrasting j-et illustrative fact. In the Jurassic or Cretaceous rocks of Queen Charlotte's Island, Mr. Richardson, of the Canadian Survey, finds Ammonites and allied cephalopods similar in many respects to those discov- ered further south by your Cnlifornia survey, and Mr. Whiteaves finds that some of them are apparently not distinct from si)ecies described by the Paheontologists of the Geological Survey of British India. On both sides of the Pacific these shells lie en- tombed in solid rock, and the Pacifip rolls between as of yore. Yet these species, genera and even families, are all extinct — wh}', no man can tell, while land plants that must have come in while the survivors of these cephalopods still lived, reach down to the present. IIow mysterious is all this, and how strongly does it show the independence in some sense of merely physical agencies on the part of the manifestations of life. Such facts as those to which I have referred, and many others which want of time prevents me from noticing, are in one respect eminently unsatisfactor}', for they show us how difficult must be any attempts to explain the origin and succession of life. For VICE PKESIDENT 3 ADDHESS. 1!) this reason they arc quietly put aside or explained away in most of the current hypotlieses on the subject. But we must as men of science lace tliese difliciilties, and l)e content to searcli for facts and laws even if they should prove fatal to preconceived views. A group of new laws, however, here breaks upon us, (1) The great vitality- and rai)id extiMision and variation of new si)ecilic types. (2) The law of spontaneous decay and mortality of spe- cies in time. (.'5) The law of periodicity and of simultaneous ap- pearance of many allied forms. (1) The abrupt entrance and slow deca}' of groups of species. (5) The extremely long dura- tion of some species in time. (0) The grand march of new forms landwards, and upwards in rank. Such general truths deeply im- press us at least with the conclusion that we are tracing, not a fortuitous succession, but the action of power working by law. I have thus far said nothing of the bearing of the prevalent ideas of descent with modillcation, on this wonderful procession of life. None of these of course can be expected to take us back to the origin of living beings; but they also fail to explain why so vast numbers of higiily organi/.ed s[)ecies struggle into existence sinudtaneously in one age and disapi)ear in another, why no con- tinuous chain of succession in time can be found gradually blend- ing species into each other, and wh}- in the natural succession of things, degradation under the influence of external conditions and final extinction seem to be laws of organic existence. It is use- less here to appeal to the imperfection of the record or to the movements or migrations of species. The record is now in many important i)arts too complete, and the simultaneousness of the entrance of the faunas and floras too certainly establi.shed, and moving species from place to place only evades the dhhculty. The truth is that such hypotheses are at present premature, and that we require to have larger collections of facts. Independently of this, however, it appears to me that from a philosophical point of view it is extremely probable that all thecnies of evolution as at present applied to life, are fundamentally defective in being too partial in their character ; and perhaps 1 cannot better group the remainder of the facts to whicli 1 wish to refer than by using them to illustrate this feature of most of our larger attempts at generali- zation on this subject. • First, then, these hypotheses are too partial, in their tendency to refer numerous and complex phenomena to one cause, or to a 20 VICK PUKSIDENT.S ADDUKSS. fow causes only, wlion all trnstwortliy aiuilojiy would iiidicato that they must result from many concurrent forces and determinations of force. We have all no donht read those inu;eniouM, not to say anuisinir)KNT 8 ADDKESS. 21 tlicir oriiiin, lio brinpjs tlio lattcM' to hciir on tlio Conner liy nn niml- o