THE EFFECTS OF DARWINISM ON BIOLOGY.

Press, Volume LV, Issue 10139, 12 September 1898, Page 5

THE EFFECTS OF DARWINISM ON BIOLOGY.

(Bx Professor W. B. Bbsham, D.Sc, M.A.)

It is to be presumed that everyone at the present day knows, with greater or less accuracy, the meaning of the terms "Darwinism" and "Biology." Nevertheless, it may not be superfluous to point out that the term Darwinism is not synonymous with the term evolution. "Various early philosophers had more or less vague ideas that the existing organic world had arisen as a result of some process or processes of modification from pre-existing animals and plants. But of these 'theories none is of any great importance except that of Lamarck, who believed that evolution depended mainly upon the inherited effects of use and disuse of parts ot the body. This theory took some hold of naturalists during the first half of the century, ere Charles Darwin and Alfred Wallace, each independently ot the other, formulated the theory of "Natural Selection," as the general and main cause of evolution.

■ Darwinism, then, is not co-extensive in meaning with evolution, but is the expression of a special means by which evolution has been brought about; it depends mainly on three factors—variation, heredity, and the great struggle for existence, which results in the "survival of the fittest," to use Herbert Spencer's expressive phrase. It is, however, not my intention to discuss evolution here, nor to argue as to whether this or that factor has been most potent in bringing it about; but to take evolution as a fact, accepted not only by every modern naturalist at the present day, but also by the majority of educated people in all countries of the world; and then, to point out briefly, what effect tins revolutionary theory has had upon biological researcbi Next let mc explain what lines of study biology covers. It is, as is evident to anyone who knows anything of classics, the "study of life," or more reasonably, the study of living things, since we are ignorant of what "life" really is. Further, biology is concerned, not only with those beings living at the current geological epoch, but with those that have lived at any and every previous era in the world's history; in other words, it includes that hybrid study, palceontology. - A living thing is either an animal or a plant; about the latter there is little or no confusion in the popular mind, but about the former there is a good deal of vagueness. The popular use of the word is sometimes restricted to those "hairy, four-legged creatures, which suckle their young." These are, however, known as mammals to the naturalist, who, by Dhe term "animal," includes them and many other things as well—birds, reptiles, frogs, fish, molluscs, crabs, crayfish, and prawns; insects, spiders; the less known worm-like creatures; corals, sea anemones, jelly fish, sponges; sea mats, sea urchins, sea cucumbers* and starfish; all these and many microscopic beings move about, and have sensation—these are animals. These can only obtain their nourishment by devouring food which contains substances having a particular and very elaborate chemical composition, and known in a general way as "proteids." | Plants, on the other hand," can make j lise of food material of much simpler chemical constitution, of a non-proteinaceous character. All living things, or organisms, can be relegated to one or other of these two great kingdoms; and this is also true of "fossils," which are the remains of, or the indications of the existence of, organisms which are now extinct. The study of plants, whether living or extinct, is botany; the study of animals, whether living or extinct, is zoology ; and palseontology as a separate science has I , no real existence, it is merely so much of the above two sciences as concerns the geologist. Now, since man is but an animal, whose , body is somewhat modified for an erect carriage, and whose brain is rather more elaborate than that of a chimpanzee, the study of "Homo sapiens" is, strictly speaking, included in zoology, but owing to special requirements and to the enormous amount of knowledge, that- has been accumulated about himself, and his affairs, habits, and opinions, the special study of man is delegated to the specialist, viz., the human anatomist and the anthropologist. Nevertheless, in considering Ihe general scope of biology we cannot exclude the final product of evolution^ Now, an organism may be studied from different points of view. We may explore its structure to find out how the various parts, or organs, are fitted together to form the connected whole—much as a boy takes to pieces a watch or other piece of mechanism, to see the wheels, &ci, which go to make it up. But in the same way the boy doesn't see "how it works"; nor can the biologist by mere dissection ascertain how the animal or plant lives. Anatomy is insufficient for the purpose of understanding all about the organism; he must discover in some way or another what purpose each organ serves in the economy of the whole organism. In fact the biologist must study the function of the parts, i.e., its physiology. And for a scientific study of plants and animals, this physiological aspect is all important, without it the biologist would, in many problems, be groping in the dark. But beyond v these two rather academic aspects of biology there are many other matters connected with an organism which demand the attention of a biologist. The habits and customs of an organism, its mode of life, its food, and the manner in which this is obtained; its enemies, and the means of defence which are brought to its aid in warding them off. All these matters are included under the old-fashioned term "natural history."

Farther, it is rarely the case that a j given animal or plant is universally distri- ' buted over the face of the earth. A particular organism may occur in a particular country and nowhere else in the world: or an organism in one part of the world, is represented in a -far distant part by & closely similar form; while, perhaps, in some intermediate area a third, similar, but different, organism is represented by a fossil. A comparison of such facto as these enables us in the light of evolution to give a fairly probable history of the animal. It made its appearance originally in the area in which it is now fossilised, its offspring wandered away in divergent directions, under street of various oirounataaceey which

possibly geology will enable us to ascertain, and ultimately reached the f»i distant spots at which the closely allied specie* are found to-day. Such * history we attribute to the "Jttatite birds—the emu, ostrich, cassowary, and rhea — which at present occupy such distant areas as Australia, South Africa, and South America.

Indeed, each animal and plxuifc has a special distribution in space and in time, and the study of ttus distribution furnished Darwin with evidence in support of his theory, but since his time this same study in its turn has received aid from the theory. and has thereby been endowed with lite, and meaning, and interest. It may be worth mentioning that in JJew Zealand the majority ol animals and plants are of great interest owing to their geographical distri outiou. .Many are absolutely confined so these islands, while others have representatives in ottier parts ot the world. J?or example, uuuiy oi our birds, like tne kiwi, the kea, tiie Kukapo, the takelui, as well as most ol our terrestrial amuu-ls belonging to the lower classes, axe in this case; while the uiaiaras only closo allies have to be looked lor in roem ot Jurassic age. And it is ot ttiu utmost lmpiatuncy to biology, and ol wie greatest interest- to scioutilic men that evi-ij detail about the habits and structure and lite history of uieyo animate should be gutheieu tage-iiier betore it is too lute. Every year sees a diminution in the bush —the wmve habiUit of these creatures —every year brings them one step ucaxex to extermination; a. result ciuo botu to the necessities ot cultivation ot the land ;uid tc the introduction oi predatory aminaJs (ag.. ferret), or more active iorms, such as toreign birds, wliicii will beat them ni the race ioi loud. In a lew years some, oi ihcm will be aa extinct ;is tne iuua iv i\ew Zealand, or as mo dodo in Mauritius, and the sohtuire in Kodriguez, all ot which sutl'ered from their inability to ily iwvay- from the intruder, man and ius ueeompauynig uiunniis.

In respect oi the habits of animals in general much mm already been wntteu, and la gathered together in "jNatural Histories, , ' bui. much oi tiub is irrelevant to science, and ot very little value to any but young children. llieio is still room for careful sciuuUJic observation in this particular domain oi biology, the outcome oi which may be utilised, u« some ut it has aheudy been utilised, for die furtherance of various commercial undertakings.

iiiology need not be a mere academic (or amateurish) pursuit. The problems with which it deais are .very far-reaching, and if the subject, in its scientific aspect, is at present confined to university, college, or other institution for higher education, it is because, in most countries, the experience and advice of the professional biologist is not sought in coses where that experience might be of general and of commercial value.

it was the study of "Natural History, '• mainly, that led Darwin to formulate, with that laborious detail for wliich lie is famous, his theory of natural selection, and the survival of the fittest. One of the first effects on biology was the remodelling of classification: (hitherto the schemes by which ani-. nialb and plants had were more or less meaningless and artificial. External resemblances, in the case of animals, were deemed sufficient for the association, of this animal with that. And although anatomy had already made great strides during the previous fifty years, yet the "eystematists" and the "anatomists" were independent of one another: a fact wihich is very much less usual new than then, seeing t'liat the facts acquired by the anatomist could have no bearing on the conclusions of the syetematists till Darwin threw the fresh light of. his theory upon them. It then became qvident that many structures, or modi-, ficationa of structure, previously passed over as insignificant, really told the tale of evolution more or less distinctly: it become, clear that more importance was to be placed on resemblances in internal anatomy' than on external characters. For example, we now know that organs bringing the organism into relation with liiie other world may be greatly changed in correlation with the mode of life, so that the external form of a sedentary animal for instance, may become extremely unlike its cousin which moves freely in the world, and has to seek-its food and fight its enemies. And, usually, resemblance in some one important internal organ, outweighs vast differences in external character. In this way, "classification" comes to have a definite meaning: it becomes "natural," and serves to indicate, as for as our. knowledge goes, the genetic relation of one organism with another: so that it is analogous to the genealogical tables which used to be the bugbear, of our childhood's history lessons. In his discu..uon as to the evidenced in favour of evolution afforded by the variow departments of nature, Darwin laid" greal stress upon embryology. This study, which is only a part of zoology or botany, if concerned with Ihe early life-history of an organism, it deals with those changes that take place in the egg, as a result of which the new individual is built up; witlh those processes by which the unicellular egg cell becomes, firstly, a multicellular organism,. and then a more and more complex embryo. It follows out the formation of orgaii aftei: organ in this embryo ,till the young organ* ism starts life* on its own account..

Darwin argued from the facts of. embryology then available that in a general way the more highly organised animal, the "higher" animal, passes during its develop; ment through stages which are permanent in "lower" animals. He recognised that, if his theory be true, each individual oiigbJ to bear evidence in its embryology of it« own ancestry; in otJher words,'. the rabbit -;. ought to present some' stage in , which it resembles its more or less fish-like; ancestor.

It was evident that an extension of the - - few facts known at that time would add to, or detract from, tlie probability of the theory of evolution; and as a consequence the study of embryology was keenly pursued in Germany and in Great Britain. At . , Cambridge, indeed, a chair was founded fot the'purpose of encouraging the science. It , was occupied by tihe late I\ M. Balfour/ brother to the distinguished politician (and gfolfer). Balfour soon gathered round him a band of enthusiastic disciples—many; oi whom have left their mark in science, and are still pursuing biological research. Year by year,increasing attention was paid to this fascinating part oi biology, with a general confirmation of Darwin's views. One of the most notable results of •embryology has been the establishment of affinities between animals apparently widely separated; thus, the humble and ugly sea* squirt (ascidian) was soon shown Dy the Russian, Kowalevsky, to be provided, at one time of its lif&i with a notochord, the forerunner of the backbone, which is present in the embryo of all vertebrates. This notochord was later, by Harmer and by Bateson, found to exist in other equally unlikely creatures. On this account (and for other similar reasons) the ascidian and these other animals have been raised from their lowly position amongst invertebrate wormlike animals, to a rank not far removed from the ancestor of man himftlf. The life history off the ascidian illustrates a phenomenon which is too frequently overlooked by the popular exponent of viz., degeneration. It is frequently assumed' that "evolution by natural selection" implies a constantly perfecting or improvement of the organism. Such is by no means the case; degeneration is a not unfrequent phenomenon As a result of embryology, "comparative anatomy*' has been placed on a sure foundation. We know, now, what organs should be properly and profitably compared with one another. Wβ have learnt to dietingniflh "homology," or likeness in origin, from ~ "analogy, , * or likeness in function. • Improved methods of research, have enabled embryologLsts and histologiste , '•- =•■ amine in greater and greater detail toe pro* < cesses by. which, cells give rise fey division to other cells, and the changes oy which '""' these cells become differentiated to form tie- \ , such and organs. And the effort .has been continually made to trace to these cells, or rather to some constituent of their substance, the material which ia passed on from parent to. offspring,, and in which may be an explanation of heredity. The attempt was made, in a purely theoretical manner, by Darwin himself, but more' recently Weismann and others have endeavoured to identify certain concrete particles in the nucleus as the responsible agents of the process. And as a result of hie studies, Weismann put forward a theory of th» "Continuity o£ germ-plasm," in virtue of which he was ledj. , to deny the possibility of tha inheritance . : ol those onaraotera which are usually termed :

acqiin -J. He believed that each cell in an eji..cvu has its own special work to perform, *i.v fts oi»i' particular.fate laid down foi it. Hit - we know a given patch of cells give rise to tiu nervoub sysUia; another group oi cc la to muscle*, and w> forth. Each ot lt«. <c groups can be traced back to a single cell at an earlier sUige ot developments »nd t.K «■ icils still furtuer backwards to the «v.L,... i ergc r g cell. .Now, "/tiMuann believed tti.fi f'< ii' B Toup can only give rise to its *,().. lii tissue or organ and to noUiing else n< viji.'.:c of some \letennming" material, \. M.fi ijc trace* back to the nucleus of the lius hyp» thesis is capable of confirmatioJi (ji reir.Ulion, and us a consequence a series iif experiments on the developing o..ilii-\<> liive oceii carried out by Hertwig, Kiiu.v. l)iK'ich> and others, such as this — An i.ijiiiv is produced in a particular set ot ctil- (say tho»e destined to form the neiv>,i;> .system). According to this theory tin , embryo at « later stage should be without thia "system, but the contrary is found to Ijf the'result. Ur, again, by pressure upon the early embryo these piesumed jiei if f- nning cells are pushed out of place, i.ther cells come to occupy their position and give rise to the nervous system. By a series of such experiments —the details ot" which would be too technical to refer to here—it has been proved pretty conclusively (for there are discrepancies in the result- " that little or nothing of Weismann s 'gennplasin theory" ia true. Nevertheless, so well founded did it appear, so convincingly did its author put it torward, that before these experiments were made it was accepted as true. Its falsity is no real bai to its value, for it has produced a new and fertile method of investigation, from which important results have been already obtained as to the conditions favourable and unfavourable to development ; results which have a distinct value in every day life. But Darwin's theory, as well as that of his follower Weismann, lias led to othei experiments of a different character; but also with a view to test the question as to whether acquired characters are, or are not, inherited. Those of the late Dr. Romanes were unfortunately cut short by his death, but his contributions to the subject of Darwinism and to postDarwinian questions will rank alongside those of Darwin himself. His results, so far as they go, led him to take a directly contrary view in the matter to that taken by Weismann, in that he believed that these acquired characters are capable of being inherited. Another series of observations and experiments and accurate measurements have been undertaken with a view to testing the amount of variation which exists in nature. 'Darwin was able to record only a few instances, and those the experience of breeder? of pigeons, of horticulturists, and others on the matter.

The various methods by which animals .are aided in the struggle for existence, suoh as mimicry, protective resemblance, warning colouration and the like, upon which Darwin laid some stress as illustrating the directions in which natural selection may act, 'have received considerable attention during the last few years. Although these ■übjects have afforded material for many a popular lecture, and may therefore appear slight and trivial, yet to the naturalist, these terms are important as being categories under which may be placed the various types of colouration: the brilliant colouration of one animal, the dull tint ot another: which con be shown, with the utmost probability at least, to be useful to the animal, and to be acted upon by natural selection

The utility of such specific characters, as the tubercles or notches in the carapace of a crab, has often been questioned: but careful experiment has proved that they are of the utmost value to the animal during that all-important process of Indeed, the various phenomena which Darwin relied upon as a support, for the theory, or us being explained by it, have each and all received careful examination, and have been subject to experiment. At the present time there is a renewal of activity in that line of research, of which Darwin himself was so conspicuous an example, viz., "Natural History." But natural history treated in a proper scientific spirit. It is of interest to note that whereas the theory of the "Naturalist" Darwin gave an impetus, at first to pure "laboratory, work of a more or less abstruse character; the subsidiary theory of the more modern "laboratory worker" (or zootomist) Weismann hae directly led to a revival of "Natural History." Among the most fruitful results of Darwin's influence on research was the desire to investigate the fauna and flora of deep ■eaa to ascertain whether in the abysses ol the ocean or elsewhere out of the general track of scientific work, there might perchance be some surviving remnant of "bygone fauna and Hera." I'his led to that magnificent expedition of H.M.iS. Challengei, the examination of the gatherings, and the publication of the results of which were only completed last year—seme twenty years, since fhe voyage took place. Here in the thirty and more quarto volumes are to be found scores and Hundreds of interesting illustrations of and evidences for Darwin's theory. For example, sea lilies and sea urchins belonging to gi<mps previously regarded at extinct were feund; fishes, living in great depths, of evidently archaic structure, like Chlamydoaelache; others, offering examples of the very varied methods of obtaining food in these dark regions, and showing the keenness of tkt struggle by the modification of one organ or another, e.g., enormous eyes or their total absence ; tflie development of phosphorescent or lightproducing organs; enormous mouths and distensible st&mp.chs, so that a, small fish can swallow one some three or four times its size.

The exueditien of tfhe Challenger has been followed by similar expeditions, carried out in a less complete manner, by other countries. Not only has the sea been thus more or less systematically explored fox organic life, but the character of the «eabotttom has aiforded material for geologists, whe have been, able to form an opinion af to the relative fixity of the great continental areas. Altogether new ideas as to the tempenvtura of tihe gieat depths, as to limit oi lift and light, and as to the depth of the sea, have also been accumulated.

Further, with the increased attention to animals, in iheir natural envirSument, and with the necessity fcr accurate experiments on the spot, biological stations have been established in all parts of the world, usually on the seashore: one important commercial aspect of which is the attention paid to all kinds of questions connected with fish. The biologist is now able to make a careful study of the feeding grounds of fish: the life history of the fishes used as food: the spawning grounds: the character and migrations of the young fish, and so forth. He is able further to experiment as to the most profitable time, place, and methods of catching the various fish: the size at which they become adult, and therefore the minimum size that should be caught: hence he is led to a consideration as to the mesh of the net: and many other matters of the utmost importance to the fishery business.

Both zoological gardens and museums have become accessories to biology. The former are no longer the resort merely of sightseers and children, but afford opportunity to the student oi Nature of studying in the life, the largei, or otherwise interesting animals which are foreign to the country. Thus, Romanes was able to study and to teach the chimpanzee "Sally" who lived for years in the London "Zoo," and thereby was able to add considerably to our knowledge of the mental capacity of this anthropoid ape.

Tile museums, too, are no longer mere store rooms: they no longer confine themselves to the exhibition of row* of stuffed specimens of mamals and birds, but endeavour, so far as space, money, and assistance are available, to make the exhibition a visible and tangible illustration of Darwinism. Thus groups of animals illustraing protective colouration: or mimicry: or variation and so forth, vary the monotony of the simple classificatory series. The effect on anthropology is as great as on other departments of biology; and, indeed, the study of man, his orte/religions, languages, aad histories, has only become a science in the true sense of the word, as a direct eoosequenw of Darwin's theory. This i* plainly seen vi more recent text books. in every subdivision of the subject, and is beginning to bi felt, and observed, in a few PitPft??/ 0 *"*?, museum8 ' especially in the Pitt Rivers collection at Oxford. Thero. Instead oi a Uttrogeneom collection of

"enrios" from this or from that country, piled up and mixed in a more or less picturesque confusion, we now find the different arts treated comparatively, so as to illustrate the gradual evolution, from its earliest known invention, of the perfect article, be it a Lee-Metford rifle, a Broadwood grand piano, an exquisite piece of pottery, or an elaborate geometrical design. For this purpose specimens are obtained one from one part of the world, another from some other part, and specimens in use at various periods of time are all arranged so as to make the series as complete as possible, from the first beginning up to the final product. In thia way an anthropological museum becomes both interesting and instructing; which cannot always be said of a mere ethnological collection.

In this brief and superficial sketch I have endeavoured to indicate rather the direction of the influence of Darwinism than the amount of that influence, which cannot, indeed, be estimated. Its influence, it may be added, is not by any means limited to biology ; there is no department of learning that has not felt its effects, as even the d-jilv Press shows.

Darwin's theory, in fact, remains as firmly established as it was thirty years ago ; nay, it is much more so, for in spite of various side issues that have been raised from time to time—some of them only to be demolished—research in biology has only gone to confirm to the full the theory that evolution has proceeded as a result of natural selection, although it is quite possible that other factors have shared in the process.