FLOWER-TRAPS.
AS far as we can gather, the years which have followed Mr. Darwin's announcement and verification of the great principle of "natural selection" as an efficient cause of changes of type in the various species of plants and animals, have tended in the minds of the greatest living naturalists to prove that, though a very powerful cause, it is not by any means the only cause which has been at work in effecting those changes, and that it will not be possible ultimately to explain many of the curiosities of organic life by the service which those organic modifications have even at any time rendered to the species to which they belonged. An illustration of the tendency to diverge from Mr. Darwin, not, of course, in relation to the great influence which the principle he has discovered has had in altering organic types, but as to the extent of the principle, is afforded by a very interesting lecture of Mr. Lawson Tait's, delivered at Bir- mingham on Tuesday, on "Insectivorous Plants," that is, on those curious flower-traps to which so much attention has lately been drawn,—flowers in which insects are not only caughtand killed, but in some cases at least digested. Mr. Lawson Tait, however, holds that there are species of plants which catch insects without digesting them, and that even when they digest the insects caught, this di- gestion is not followed by any such direct advantage to the plant as we derive from nutrition, i.e., from the assimilation of our food. "It must not be supposed," he writes, "that every fly-trap is a fly- digester, still less must it be taken for granted, as it has been too readily in the case of the sarracenia, that fly-digestion must neces- sarily mean absorption of the products. In fact, direct absorption of the products by the leaves is so hypothetical, that I am inclined to disregard [? disbelieve] it altogether. I know Mr. Darwin is in- clined to accept it, but I do not know his grounds." And he added at the end of the lecture, "What becomes of the products of digestion is a problem still unsolved, and on this point Mr. Darwin and I differ. Mr. Darwin is of opinion that the leaves absorb the products of digestion. I thought so at first, but I have failed to find any evidence of absorption by the surface of the leaves. On the other hand, my experi- ments tend to show that the products of digestion run down the leaf-stalk to the roots, and are there absorbed as manure is." Of course, if that be so, the roots may assimilate a portion of the fluid in which the insect has been digested, though much of it may be wasted in the soil, but even if the manuring of the roots by these digested insects is useful to the growth of the plant, it can hardly be of the same importance to it as it would be if the whole products of digestion were, as Mr. Darwin supposed, absorbed by the leaves. And in the cases mentioned by Mr. Lawson Tait, in which the flower-traps catch the insects Without digesting them at all, it is still less likely that the trap is essen-
tial to the health and growth of the plant, and therefore that it has been gradually elaborated by the process of natural selection through the benefit it has thus conferred. Indeed the cases are not few in which it is admitted to be, in the present state of our knowledge, impossible to ascribe particular organic modifications to the prin- ciple of natural selection. In his first treatise on the subject, Mr. Darwin himself, if we remember rightly, admitted very candidly that there were many cases in which natural selection could hardly be supposed to account for the elaboration of a particular organic structure, for the very simple reason that, as in the case of the quadruped's tail which is of service in flapping away insects, it would not be useful at all till it had already attained a certain completeness and magnitude, so that the initial stages of growth could not be ascribed to the advantages it bestowed. And the same may be said in relation to these flower-traps, even if they do contribute to the food of the plant. Till the trap was perfect enough to catch an insect, it could be of no use in catching in- sects, and a perfect trap could not be elaborated all at once. Indeed if Mr. Lawson Tait is right, it would seem that the in- sect-catching plants are not always insectivorous plants, and that even the insectivorous plants often appropriate only a certain pro- portion, if any, of the products of the insects thus digested.
We do not know, indeed, why there should be any disposition at all to believe that in the natural world the only ultimate cause of faculty is the utility of that faculty. That usefulness is one cause, and a most important cause, of the growth of useful characteristics Mr. Darwin has admirably shown. But is there the least a priori presumption that this may be the only cause ? If we were to discover for certain that there are flower-traps which get no sort of advantage out of their insect-prey, would it be at all more surprising than the fact that there are so many human traps in the shape of longings and desires,—for instance, according to most physiologists, the appetite for fermented liquors,—which bring no advantage, but almost pure mischief, to the creatures whose natures contain these traps, and who take such pains to bait them skilfully? There are flower-traps which are fatal enough to men, as well as the flower-traps which are so fatal to insects, and traps of which it would not be difficult to show that the victims are never either digested or absorbed by the living trap which catches them. Avarice,—the love of money for its own sake, and not for the sake of the advantages which it brings,—is certainly such a trap, though not of the most flowery kind, and one which closes on its prey without bringing anything but harm to the subject of the passion. Almost all the occupations which most absorb men and devour their hearts, the love of gambling, the delight in mere intellectual dexterity,—such as is shown, for instance, in the passion for billiards or chess,—nay, the love of music itself, is more or less of this nature. We do not doubt that many of them are harmless, and that some of them, like the love of music, are ennobling, but few of them indeed are of a kind to give any great advantage to their devotees in the conflict for existence' with other men, while many of them are a distinct deduction from the efficiency of the races of men in whom they are most h ighly developed. Indeed, the effect of culture in developing a very high sort of devo- tion to useless intellectual amusements in the higher races, is one of the most remarkable proofs conceivable that all which grows up in this universe is by no means to be accounted for, either in the present or in ages long gone by, by the advantages it brought to human beings in the conflict for existence. The love of play in children is, of course, explained now-a-days by the necessity for rest from useful occupations ; but why, on the hypothesis that utility has been the great efficient cause of all organic changes, was there not some race in which all the rest which is usually gained by play was found in varieties of useful work,—so that every moment of a child's life should be utilised and economised for the purpose of fitting it for the conflict of life ? The only possible answer, as it seems to us, is that the nature of man is so made as to crave the pursuit of other ends besides utility ; but this is really admitting that other ends besides utility have always existed and always will exist in the ground-plan, as it were, of the universe. For you cannot reply that a creature which lives for a variety of ends is necessarily more prosperous than one which lives only for the sake of life, without conceding the very point,—namely, that before you can calculate what is useful to any being, you must have already before you a constitution in which there are a variety of wants and functions independent of utility, so that utility must be reckoned in reference to the satisfaction of those wants and the development of those functions, and could not be reckoned at all without them.
As far as can be seen, it is as true of the natural world-as it is of the human world, that the growth of a great deal in it
can be referred to the use which it served. But the growth of a great deal else must be referred to ultimate diversities of end in the constitution of the universe, which cannot be shown, or even reasonably conjectured, to have been useful to the natures in which those diversities existed. We suspect that the more time naturalists give to the causes which have been at work in nature, the more they will see that the principle of natural selection, powerful as it is, is a limited one. Indeed, will it not be found that a good many of the varieties of the lower orders of species are mere anticipations of and preparations for the varieties of the higher orders of species which are to be developed out of them? And as there can be no question that amongst men the principle of competition or conflict, though a very active one, is by no means the only one at work, we are not surprised to find traces in the lower orders of creation of other principles which seem simply unintelligible where they are, but which, when they reappear in a new form as elements in a being -of so composite and yet so clearly moral a nature as man, have -their meaning and value, if only as affording opportunities for discipline and occasions for self-control.
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