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the calyx (s) or outer and green part of the flower; or, according to some botanists, by the calyx alone, whose green leaves become thickened, red, and glistening as the summer passes into the autumn, and come to enclose the true fruit (fr) in the form of the little "carpels " similar in nature to those on the outside of the Strawberry. So that the difference, in one botanical theory at least, between the "hip" of the Rose and the Strawberry, simply consists in the fact that the Rose flowerstalk is hollow and has the fruits inside, whilst the end of the Strawberry flower-stalk is solid, and has its fruits outside. The Apple and Pear likewise exhibit much the same arrangement as the Rose and Strawberry in respect of their fruits. If we suppose the hip of the Rose to have its walls extremely thickened and fleshy, we should FIG. 69.-ROSE FRUIT. convert it into a form of fruit resembling the Apple

or Pear. No less interesting is the nature of the Fig, which, to be properly understood, should be examined as it grows in the hothouse. Slice your fig longwise (Fig. 70 a), and you will see in its interior, not seeds, but "flowers"; some with stamens (b) alone, others (c) with pistils alone. The Fig appears before us as another example of the hollowing of the flower-stalk, with this important difference, that not merely the fruits but the flowers are contained in its interior.

It only remains for us to sum up the results and general conclusions to which our brief study of the science of likenesses may be said legitimately to lead us. Turning

[graphic]
[graphic]

FIG. 70.-SECTION OF FIG.

firstly to the features we have just been discussing, we have noted, for instance, that the leaf was the type of the whole plant, and that as the leaf became modified to form the "flower," so that flower and its parts, still representing leaves, became further altered to form the "fruit" under all its varied aspects and forms. From a simple structure-the leaf-we thus discover, by the aid of the science of likenesses, complex and elaborate organs and parts to be developed. What lessons do such examples teach us concerning the order of Nature at large? Do these lessons argue in favour of evolution or against that theory of Nature? The answer is not for a single moment doubtful. If, as our inquiry shows, it is the way of Nature to produce many and varied structures by the modification of one simple organ or part, surely there is no greater wonder involved in the idea, that by the same process of development she has woven from simple forms, the

whole complex warp and woof of the living world. When we see Nature in her abnormal methods of development revealing to us, under the guise of her sports and freaks amidst the flowers, the true composition of the pistil and stamens, or altering the same structure to form the varied fruits; when we discover that the complex skull has apparently been built up through slow and gradual modifications from skulls of simpler type, which vanish away, in the lowest confines of the vertebrate animals, and disappear in the barely defined skulless "cord" of the lowest fish, we may not esteem it an impossibility that all organic forms have been evolved under like conditions of development.

Nor must we omit to think of another important point involved in the study of homologies. If Nature is, as we have shown, liable to modify and alter continually the work of her hands, can such a practice be held to favour the origin of new species by the way which evolution points out? When the flower returns to the leaf-type, or when it exhibits variations from its usual form and structure, is Nature going back or reverting to former conditions? or is she initiating paths which lead to new species? The answer to both of these queries may be given in the affirmative. When the flower grows into its leaves, that is a "reversion," a stepping backward to the primitive and simple type. When, on the other hand, the plant shows a tendency towards complexity, instead of simplicity-to alter in favour of increased development-then is seen the tendency to progression and elaboration of the type. Both tendencies hold sway in Nature, and the one is as inexplicable as the other, save on the theory of Evolution. From the monstrosity of the flower a new "variety" springs, and in time the variety becomes a "race," and the race in turn a new "species." Thus, whilst the course of Nature before our eyes runs not smoothly but in an apparent irregularity, the deeper faith in a law-governed universe, not as yet fully comprehended or known, convinces us that with the higher knowledge of to-morrow, the irregularities of to-day will resolve themselves into parts of an ordered system. It is not without good reason for believing in the reality of the convictions which nature-studies inspire respecting the government of this world's order, that we find Professor Parker maintaining that "the study of animal morphology leads to continually grander and more reverential views of creation and of a Creator. Each fresh advance shows us further fields for conquest, and at the same time deepens the conviction, that, while results and secondary operations may be discoverable by human intelligence, 'no man can find out the work that God maketh from the beginning to the end.' We live as in a twilight of knowledge, charged with revelations of order and beauty; we steadfastly look for a perfect light which shall reveal perfect order and beauty."

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VIII.

THE EVIDENCE FROM MISSING LINKS.

WHEN the Darwinian theory of the origin of living species and other theories of evolution were yet in their infancy, the subjectmatters of the present paper had attained notoriety, if not fame. The early critics of the hypotheses of evolution were not slow to fix upon "missing links" and their nature, their assumed absence, and the impossibility of supplying them, as weapons of satisfactory kind and lasting strength, against such ideas of the order in which the living universe had been formed. Especially has the phrase found favour in the eyes of critics of an unscientific cast of mind-those "old ladies of both sexes," to use Huxley's words, who consider the "Origin of Species" "a decidedly dangerous book," and who regard most contributions to the literature of evolution as works of darkness in the most literal sense of the term. Persons who would have been puzzled had they been asked to mention a single example of a case where "missing links" were required, nevertheless were found ready with much unction to declare that Mr. Darwin could never be expected to fill the gaps in question; and the argument as against evolution, in the early days of which we are speaking, was frequently supposed to be clenched with the triumphant query, "Where are the missing links?" A feature of Darwinism and evolution, not to speak of natural history at large, so apparently familiar as the subject before us, deserves some detailed examination. It is not too much to say, that even with the lapse of years, and with the better understanding by cultured persons at large of evolution, its weaknesses and its strength, the nature of "missing links " is often imperfectly understood. Apart from the necessity for some clear understanding of what is demanded by the opponents of evolution, and of what evolutionists and naturalists are able to present in reply to these demands, the present topic may be said to have grown in importance with the most recent discoveries in geological science. Its true nature, and its attitude to the existing phases of evolution, are therefore matters for careful inquiry; since their investigation may powerfully aid the solution of the great problem which evolution endeavours in one phase to solve-the how and why of living Nature and her ways.

The widespread recognition, even in the popular mind, of the importance of the discovery of "missing links" between existing

species of animals, in so far as the welfare of evolution-theories is concerned, is not difficult to trace or account for. Taking for granted the very reasonable and obvious admission that any theory of evolution must rest upon the idea of the production of new species by the modification of the old, it follows that in our examination of living nature we should expect to find evidence of the connection between the varied forms of life in existence. From the monad up to man, the evolutionist postulates an unbroken series-not, indeed, as many suppose, in one straight undeviating line, but rather after the idea of a great tree with countless branches, offshoots, and diverging twigs, which, however, unite in their lower limits in a common stem. Now, is it possible, when we look around at the varied forms of animal and plant life, to trace this unbroken sequence, this continuity of structure, and this connected relationship? The common observation of nature, not to speak of even an elementary acquaintance with popular zoology, forbids the idea, and at once negatives the supposition. The forms of life, animals and plants, fall into groups and divisions of varying extent and different rank in the scale of creation. In each large group we include a number of lesser divisions, the members of which are united by certain common characters. But even in the smallest of our classes or orders, the gaps betwixt the included forms are many and wide; and Nature, as we observe her processes, does not appear to supply the "missing links," in the existing order of affairs at least. In that great sub-kingdom of the animal world which zoologists have parcelled out as the Vertebrata,-or the territory wherein man and quadrupeds reign as the aristocrats, birds and reptiles as the middle classes with their varied estates and ranks, and frogs, toads, and fishes as the lower orders and substrata of vertebrate society, the gaps existing between the various classes are very patent and clear to the merest tyro in natural history. Not even the proverbial old lady with a marked partiality to a belief in the marvellous in natural history, or towards a literal interpretation of the compound zoological character of certain wondrous beasts mentioned in ancient fables, could be brought to entertain seriously the idea of the existence of an animal half-reptile, half-bird. Still less easy is it for the popular mind to conceive the existence of a creature midway as to structure between the bird and the quadruped. Whilst certain small jokers-a race happily becoming, as regards scientific matters, well-nigh extinct-might be perfectly safe in challenging zoologists at large to produce the "missing links" between man and his nearest animal relations; or to show on Lord Monboddo's hypothesis, the various stages in the decline of man's caudal appendage, upon the disappearance of which that witty savant is presumed to have founded a large part of man's physical and moral supremacy. Amongst lower forms of life the gaps are equally apparent, and the

continued distinctness of each species would seem to argue powerfully at once in favour of the "special creation" of the varied kinds of animals and plants, and against the evolution of new species from the old, and against the hereditary connection of species one with another. The argument derived from the visible gaps between even nearly related kinds of animals, was therefore too apparent to be overlooked by popular critics of evolution, and it was also too important to be made light of by evolutionists themselves. "Distinct now, distinct always," was the opinion which was duly expressed regarding the nature of species, in the early days of the historical controversy concerning their origin. We may not be surprised, therefore, to find Mr. Darwin, in speaking of this subject, saying that one objection to his theory, "namely, the distinctness of specific forms, and their not being blended together by innumerable transitional links, is a very obvious difficulty;" and again, "Why is not all nature in confusion, instead of the species being, as we see them, well defined?" Alike grave, then, to evolutionists and their opponents is the question of "missing links." Let us endeavour to examine this question in the light of recent research, with the view of determining to which side the balance of evidence, duly weighed, will lead us.

Amongst the procedures commonly witnessed in our courts of law there is one which I believe is styled, in legal parlance, "taking an objection to the relevancy of the record or indictment." The essential feature of that procedure consists in one of the interested parties showing that certain parts of the statement of facts made by the opposing side involve items which may be absolutely untrue or incorrect, and which therefore require to be expunged from the list of matters involving litigation. In this way the details of a lawsuit become simplified, and the chariot-wheels of justice are enabled to roll easily onwards in that glorious ease and uncertainty of movement which is one of the most ancient if also unsatisfactory characteristics of legal science and practice. The contention before us at present in one respect admits of its issues being amended through an objection to their relevancy. The chief points for discussion are those concerning the need for "missing links" according to the theory of evolution, and the ability or inability of the evolutionist to supply them. Let us suppose, however, that counsel for the evolutionist moves the relevancy of these points. The following will be his line of argument :-" It is demanded that we produce the missing links,' or transitional forms between existing species. Unquestionably the demand is a just one; and in furnishing its reply, it is clear we must point out such links either in the existing world, or in the fossils found in rock formations, as representing the life-systems of the past. We shall be able presently to demonstrate that whatever evidence geology has to show is all in our favour, and that where a

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