22 APRIL 1882, Page 20

A BOTANIST ON EVOLUTION.* THE unpretending little volume which we

would introduce to our readers, whatever may be said against it, is, at all events, not the result of superficial knowledge, or of interested study. Dr. Gray is, we believe, the first systematic botanist of our slay, and in addressing hearers or readers on any subject con- nected with science, claims at least the respect due to one who knows what science means. Of the narrowness characteristic of the mere physicist, on the other hand, the work before us shows no trace. It is addressed to human beings as human beings, assuming no more special qualification than that desire for harmony and simplicity in our intellectual conceptions

* Natural. Science and Religion. Two Lectnrcw, delivered to the Theological School of Yale College. By Asa Gray. New York : Chicle, Scribner's Sons. 1880.

which may surely be regarded as an equipment of the ordinary human being, and manifesting a reverence for the hierarchy of knowledge strangely divorced, in our own day, from an habitual interest in its lower phases. The book is one of a kind not uncommon among us, but the scien- tific acquirements of the writer, in combination with its aim, give it a distinct individuality. We know of no one so distin- guished as Professor Gray in the scientific world who retains any share in his conviction that all which we sum up in the name of science is but a part, and the least important part, of that which it imports us to treat as a reality; and if we must, allow that this conviction is not here set forth with all the dis- tinctness and force which characterise what is directly scientific, this is only saying in other words that the one lesson belongs to that region in which language is adequate, and the other to that in which it is no more than a finger-post, suggesting ideas which it does not follow up, or map out. If we

cannot discover here an entire triumph over this difficulty, we may recognise a kind of approach to it that is almost as rare, in a. complete sequence of conviction, bridging the gulf that severs

the seen from the unseen, and that peculiar temperance which belongs to knowledge in the face of a doubt which it compre-.

hends,—often the only contribution which can be brought by human wisdom to human perplexity. The little work is entirely popular in tone, and in extracting for the reader its main pur- port, we have only to copy a paragraph here and there, and translate the intermediate exposition into our own dialect.

The doctrine of Evolution, as we understand it, is no more than the systematic exhibition of the inherent unity of Nature. Nature was always regarded as in one sense a unity, — it was supposed to be the result of a single will. But the evolu- tional doctrine regards it as a unity within itself. We have no need, the evolutionist tells us, to turn to anything beyond nature, in order to learn that nature is one. It is a self-con- tained, coherent reality, developed from within. The mere study of its separate departments forces us to recognise that, however sharply contrasted are their extreme developments, their lower phases are indistinguishably blended. What can be more appar- ently diverse than the animal and the vegetable kingdoms? A moss and a crystal are far more similar than a man and a tree. Yet it is the general belief of scientific men that all the tests which were supposed to differentiate these two kingdoms of nature have disappeared, under the progress of research. "A new article," says Dr. Gray (p. 12), " has recently been added to the scientific creed,—the essential oneness of the two king. doms of organic nature." The boundary line which has been traced between them is subject to invasion from either side, and it would appear that the matter could not be compromised by changing the division line to a strip of neutral territory, as Haeckel has proposed, for we have thereby only exchanged one difficulty for two, the distinction of this tertiurn quid from plant, on the one hand, and animal, on the other, being the original difficulty doubled. We cannot imagine these relations to be described in clearer or more rememberable language than the following :—

" The former conviction that these two kingdoms were wholly different in structure, in function, and in kind of life, was not seriously disturbed by the difficulties which the naturalist encoun- tered when he undertook to define them. It was always understood that plants and animals, though completely contrasted in their higher representatives, approached each other very closely in their lower and simpler forms. But they were believed not to blend. It was implicitly supposed that every living thing was distinctively plant or animal ; that there were real and profound differences between the two, if only they could be seized ; and that increased powers of in- vestigation—microscopical and chemical—might be expected to dis- cover them. This expectation has not been fulfilled. It is true that the ambiguities of a hundred years ago are settled now. The zoophytes are all remanded to their proper places, though the animal kingdom at first claimed more than belonged to it. Bat other, more recondite and insurmountable, difficulties rose in their places. The best, I am disposed to say the settled, opinion now is, that there are multitudinous forms which are not sufficiently differentiated to be distinctively either plant or animal ; while, as respects ordinary plants and animals, the difficulty of laying down a definition has be- come far greater than ever before. In short, the animal and veget- able lines, diverging widely above, join below in a loop." (pp. 10.11.)

This blending of the two kingdoms on the side of the animal kingdom is not altogether a new thing. We have all been told, as children, that zoophytes were animals so low in the scale as to be indistinguishable from the plant world, though this inde- finiteness, as Dr. Gray reminds us, was always supposed to be the result rather of our inadequate power of investigation than of a mixed character in its objects. To recognise this tendency to blend in any other direction than at the point of junction be- tween the two kinds of being, on the other hand, is something altogether new. The botanical research of our own day has revealed to us animal characteristics in the distinctly vegetable kingdom, has shown us that not only do animals sink into vegetative life, but that plants, in certain directions, may be said to rise into animal life. The facts have, indeed, been long familiar, but the curious habit of regarding them as exceptional —mere lusns naturae—" as if," says Dr. Gray, "the play of Nature were different from her work," blinded naturalists, in the pre-Darwinian era, to their true scope. We will here again copy, instead of summarising, our author :—

" Is there not an independent movement, in response to an external impression, and in reference to an end, when the two sides of the trap of Diona33 suddenly enclose an alighted fly, cross their fringe of marginal bristles over the only avenue of escape, remain quiescent in this position long enough to give a small fly full opportunity to crawl out, soon open if this happens, but after due interval shut down firmly upon one of greater size which cannot get out, then pour out digestive juices, and in due time reabsorb the whole ? So, when the free end of a twining stem, or the whole length of a tendril, out- reaches horizontally and makes circular sweeps, and secures thereby a support, to which it clings by coiling, so bringing the next tendril nearer the support ; when a free, revolving tendril avoids winding np itself uselessly around the stem it belongs to, and in the only prac- ticable way, namely, by changing from the horizontal to the vertical position, until it passes by it, and then rapidly resumes its horizontal sweep, to result in reaching a distant support,—is it possible to think that these are not movements in reference to ends ?"

And this selective movement with reference to ends may surely be described as one of the chief characteristics of animal life.

While, then, at one end of the scale the largest genera of natural objects lose the exclusive unity which has been ascribed to them ; at the other end, those smaller unities which we know as species exhibit a like uncertainty in their boundary line. The field of botany is one on which this uncertainty is brought forcibly home to the observer, and if it filled the domain of natural history, we can hardly imagine that the theory of the immuta- bility of species could ever have existed. Every one who has ever tried to name a newly-found wild flower, knows how hard it is to make any floral characteristic the absolute test of species. -" The patient and plodding botanist," says Dr. Gray (p. 40), " spends much of his time in the endeavour to draw specific lines between the parts of a series, the extremes of which are patently different When he is addressed by the popular argument—' if one form and one species have been derived from another, show us the intermediate forms which prove it'—be can only ejaculate his wish that this ideal vegetable kingdom were the one he had to do with." The one with which he is conver- sant exhibits, we may almost say, little except intermediate forms. Dr. Gray says he feels towards species somewhat as the unbeliever in ghosts, who said he had seen too many to believe in them. He has " been at the making and unmaking of too many, to retain any overweening confidence in their definiteness and stability." And, indeed, one would think it must always have required the strongest theoretical propensities in any observer of the vegetable kingdom to feel anything else. The very concep- tion of individuality, says Dr. Gray—taken as it is, primarily from our own consciousness—becomes vague and shadowy in plants, and as we descend in the scale, we find ourselves in that region, fully realised only in the mineral kingdom, where there is no question of many or few, but only of more and less. Nothing is more instructive with regard to the true character of species than this intermediate position of the vegetable world between the' istinctness of animal life and the continuity of mineral existence, Less than any other student of nature, is the botan- ist able to forget that he follows at a long distance behind the subtility of Nature, forcing her delicate variations into rough compartments, of which the artificial character is revealed by the fact that he is obliged to be constantly changing them. The views of the new and the old science may be compared respec- tively to the musical knowledge of a learner who should know only the common chord, and that of one who should recognise this as a succession of stages in the sequence of semitones which we know as the chromatic scale. Nature strikes the chord for our ear, she does not allow us to follow the gradual progres- sion by which she passes from key-note to third, to fifth, and to octave. But a fine ear catches an intermediate note now and again, and recognises the audible part of the scale as a series, differing only in degree. Even so, the ohange from plant to animal—and a fortiori, from one species of either domain to another—was accomplished, we may be well assured, by delicate gradations of which Nature allows us a glimpse here and there, but refuses to exhibit in their completeness. It is only those who know her through books who can imagine, whatever they may believe, that the framework in which we have arranged her productions is anything but a human invention.

To the naturalist, therefore—even if he were also an earnest Theist—the publication of Mr. Darwin's first scientific work (we would carefully thus limit our assertion), came as a welcome deliverance from a confusing entanglement with notions which it was impossible he should ever have really incorporated with his scientific creed, and which had no vital connection with any other. In the pre-Darwinian era, that large and varied circle of catalogued observation known as natural history, which, for so many, forms the most interesting region accessible to the explorer of the kingdom of Science, was a mere outlying pro- vince, paying rich tribute, but hardly incorporated with the imperial government ; and still retaining a certain amount of hostile allegiance with which it was dangerous to intermeddle. While you might not venture to deny that the difference be- tween a primrose and a cowslip was supernatural, you could hardly consider yourself the inhabitant of a domain loyal to the single authority of the laws of Nature. This uncertain tenure of valuable territory was for ever ended by the publica- tion of the Origin of Species by Natural Selection. Mr. Darwin then justified the title, up to that time so inap- propriate, which we might fancy had been bestowed on botany and zoology by a sort of prophetic instinct ; —he made natural history historical. He changed a series of clumsy guesses to a genealogy. And the sudden fame of his work measures not only its own value, though that is much, but also the large amount of craving for some such intelligible scheme of organic existence, ready to precipitate itself as opinion at the first opportunity. Here was a coherent, intelligible scheme of things bringing order into confusion, and demanding, in its original form (and very little in the form in which Dr. Gray accepts it), absolutely no concession that any one can help making who uses his eyes and ears, and who is not prepared to assert that a sickly creature is likely to live as long as a strong one, and other absurdities of that kind. For part of this scheme was, we are here happily reminded, as little open to question as the assertion "that round stones will roll down hill further than flat ones," and though it is with some reserve that Dr. Gray accepts what is truly hypothetical in it—he believes, if we have not misunderstood him, that the gradual process of variation is at the production of a new species quickened by some high tide of creative power, perfectly natural, but hitherto mysterious, much as individual life is thus quickened—we know not that Mr. Darwin would consider that this modification interferes with his argument, and we are certain that, from a logical point of view, the theory is left untouched, in its main features, by any similar change. Now, what, from a theological point of view, had to be given up, to accept this P Nothing, on the one band, that might not be accepted by a de- vout Theist, and nothing, on the other hand, that had any hold on the intellectual world. We think Dr. Gray a little underrates, and that it is the fashion somewhat to under- rate, a concession not included in these words. So far as Christianity was committed to any theory of the his- toric origin of human society, Christianity and Darwinism could not both be true. But it was a small minority of think- ing Christians who believed that Christianity was thus com- mitted, and the only narrative to which such persons clung with anything that could be called conviction—the history of Christ —stands apart from the scheme endangered by Darwinism to an extent that would surprise many who either have never ventured, or never cared to examine their connection. The notion that Mr. Darwin's hypothesis is antagonistic to Christianity in the sense that on logical ground it provides some rival for a Creator, is wholly baseless. Natural selection cannot be invoked as the cause of that on which it operates. Probably nobody ever said it could, certainly Mr. Darwin never did. But much of what is vaguely called Darwinism demands some such assumption, and it is by no means superfluous to point out, as Dr. Gray does, that all which is in the new philosophy to take the place of Creation remains just as inexplicable as it ever was. Natural selection does not explain why there are various forms of living organisms, it only explains why there are not more. It is of itself a mere source of destruction, the origination comes from elsewhere.

Still, we have to confront the unquestionable fact that almost every thinker of eminence who has accepted Darwinism, has rejected Christianity, and even Theism ; and that the new science has, beyond all doubt, given a strong stimulus to the dominant materialism. We wish that Dr. Gray had justi- fied his avoidance of any attempt to explain this fact by dis- tinguishing the so-called philosophy of Evolution from the hypothesis of Darwinism, as clearly as he has distinguished the hypothesis of Darwinism from the facts of natural selection. We must not here attempt to fill the hiatus, but we may point out that the true issue, as it lies be- tween Materialism and a belief in the Unseen, may be thus stated. Supposing natural variation, under the sifting influence of natural selection, to be fully adequate to account for the difference between a man and a jelly-fish, still, it may be asked, —Is the fact which you call variation, ultimate, in the same sense in which the fact of creation is ultimate ? Unquestionably, it is familiar. It is a true cause, working under our eyes. Whether it has done all or not, it must undoubtedly have done much. But let us not confuse familiarity and ultimateness. I come into my room, and find that some papers of great value, which I had carelessly left on the table, are smouldering on the hearth. The window being open, I have no difficulty in believing that a sudden gust has destroyed what I rained. I see papers blown about by the wind often enough. But it is no more an ultimate fact that air should move than that paper should move. Suppose me to be told, on the other hand, that at the moment I was endeavouring to save the remnant of my papers, a vindic- tive and unscrupulous enemy was seen hurrying from the house, an explanation of their destruction is suggested to me which is an explanation in a different sense from the first. The purpose of destruction does not simply add another link to the chain of cause and effect, but brings it in contact with some- thing more original. Supposing that it became a fact because it was first an aim, it is explained in the fullest sense in which any fact can be explained. Change in the outward world is ex- plained, when it is construed as purpose in the inner world; here we attain something ultimate, and the mind is satisfied, and seeks no further regress.

We have chosen a case of human destruction to set side by side with the theory of the Divine Creation, because human pur- pose is, unhappily, so much more often exhibited in that form ; but our object is now simply to make the issue clear, as inter- preters of Dr. Gray's views upon it. Natural selection, which was supposed to obliterate purpose, affects the argument for it, he considers, only in lengthening the chain of preliminary event, before it reaches that act of initial will beyond which there is no regress. We think that this weighty truth would be clearer, if he had recognised explicitly, as he does implicitly, the distinct. ness.of the two questions,—Does the theory of natural selec- tion leave the argument for design unimpaired and—Does this theory add any new perplexity to Theism ? The second is not a mere restatement of the first in a different dialect, and we, at least, should answer them differently. Dr. Gray in one place does the like, but the truth is, we should imagine, that it is not easy for him to represent to himself clearly and steadily the mental condition of one who supposes that belief or disbelief in God depends on any speculations as to the origin of things. Purpose in the outer world, we should say—and we imagine he would agree with us—has always been discernible to him, and. to him alone, who discerns purpose in the inner. If the moral law witnesses to a lawgiver, the Creation will witness to a Creator. But there are different degrees of non-demonstrative evidence, and we believe that the change introduced by Dar- winism makes the dependence of the outward on the inward testimony very much closer. Perhaps Dr. Gray means much the same in conceding that though Darwinism has not originated any new difficulty, it has brought into pro- minence those which were already existing. But his mean- ing would have been more distinct, here and elsewhere, if he had remembered that in saying Darwinism has brought in no new difficulty, he is not answering those who consider that it has weakened evidence which they could fall back upon in confronting old difficulties. We have always thought, for our own part, that such books as Paley's Natural Theology raised as many difficulties as they solved. But those who felt the argument there set forth a prop of their faith in creative will, cannot but have found their faith affected by a theory which would not accommodate itself to that argument, all difficulties, meanwhile, remaining what they were.

However, the interest of this little book—and to us, it is a very

profound and vital interest—is not that it puts in a new light the perplexities which our time has evoked from comparative. shadow, but that it forces us to feel that one who has spent! a lifetime in the studies which emphasize and illustrate those; perplexities still finds them insignificant, in comparison with all that bears witness to an abiding order, far below the ebb and, flow of visible things which for a time conceals it. To know the seen order, and discern the unseen, is a distinction in our time wonderfully rare. It has not always been so, and the time will doubtless come when it will cease to be so ; but for the present, there can be no doubt, as a matter of fact, that the students of the visible order are led away from all belief in the Invisible,—a fact forced upon us, if by nothing else; at least by the numerous attempts at mediation between Science and Faith; which almost rival, in their prominence, the separate utterances. of either. We believe that what is demanded of those „who would approach such a difficulty is less that they should solve it, than that they should recognise it. What renders so many attempts to deal with doubt futile is not that the faith which meets it is too weak, but that it is too blind ; it cannot discern those hindrances which hide its.object from the sight of othersi. and is therefore powerless—we do not say to remove them, that is rarely within the scope of any human power—but to give those who see nothing else the confidence that it is possible to see them, and also to see something larger. We pay a high but not extravagant compliment to Dr. Gray, in saying that he May be cited as an exception to this rule.

The best contribution that can be brought towards the healing of the long strife is that one who knows each antagonist should declare that he finds a common element in their message, even if he be unable to translate it. And this weighty contribution to a remedy for the great disaster of our day is what we find in the little work—slight and unpretending as it is—the main purport of which we have in the preceding remarks attempted to set before the reader.