or devil-fish belongs to a widely different class of animals from a true fish, and yet its eye, in general appearance, looks wonderfully like the eye of a true fish. Now, Mr. Mivart pointed to this fact as a great difficulty in the way of the theory of evolution by natural selection, because it must clearly be a most improbable thing that so complicated a structure as the eye of a fish should happen to be arrived at through each of two totally different lines of descent. And this difficulty would, indeed, be almost fatal to the theory of evolution by natural selection, if the apparent similarity were a real one. Unfortunately for the objection, however, Mr. Darwin clearly showed, in his reply, that in no one anatomical feature of typical importance do the two structures resemble one another; so that in point of fact the two organs do not resemble one another in any particular further than it is necessary that they should, if both are to serve as organs of

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sight. But now, suppose that this had not been the case, and that the two structures, besides presenting the necessary superficial resemblance, had also presented an anatomical resemblance; with what tremendous force might it have then been urged, "Your hypothesis of hereditary descent with progressive modification being here excluded, by the fact that the animals compared belong to two widely different branches of the tree of life, how are we to explain the identity of type manifested by these two complicated organs of vision? The only hypothesis open to us is intelligent adherence to an ideal type." But as this cannot now be urged in any one case throughout the whole organic world, we may, on the other hand, present it as a most significant fact, that, while within the limits of the same large branch of the tree of life we constantly find the same typical structures modified so as to perform very different functions, we never find any vestige of

these particular types of structure in other large divisions of that tree. In other words, we never find typical structures appearing except in cases where their presence may be explained by the hypothesis of hereditary descent; while in thousands of such cases we find these structures undergoing every conceivable variety of adaptive modification.

Consequently, special creationists must fall back upon another position and say,-"Well, but it may have pleased the Deity to form a certain number of ideal types, and never to allow the structures occuring in the one type to appear in any of the others." I answer, undoubtedly it may have done so; but if. it did, it is a most unfortunate thing for your theory; for the fact implies that the Deity has planned His types in such a way as to suggest the counter-theory of descent. For instance, it would seem to me a most capricious thing in

the Deity to make the eyes of an innumerable number of fish on exactly the same ideal type, and then to make the eye of the octopus so exactly like these other eyes in superficial appearance as to deceive so accomplished a naturalist as Mr. Mivart, and yet to take scrupulous care that in no one ideal particular should this solitary eye resemble all the host of other eyes. However, adopting for the sake of argument this gigantic assumption, let us suppose that God laid down these arbitrary rules for His own guidance in creation, and let us see to what it leads. If, as is assumed, the Deity formed a certain number of ideal types, and determined that on no account should He allow any part of one type to appear in any part of another, surely we should expect that within the limits of the same type the same typical structures should always be present. Thus, remember what desperate efforts, so to

speak, there have been made to maintain the uniformity of type in the case of the arm, and should we not expect that in other and similar cases similar efforts should be made? Yet we repeatedly find that this is not the case. Even in the whale, as we have seen, the hind-limbs are not apparent; and it is impossible to see in what respect the hind-limbs are of any less ideal value than the fore-limbs, which, as we have also seen, are so carefully preserved in nearly all vertebrated animals except the snakes, where again we meet in this particular with a sudden and sublime indifference to the maintenance of a typical structure. Now I say that if the theory of ideal types is true, we have in these facts evidence of the most unreasonable inconsistency; for no explanation can be assigned why so much care should have been taken to maintain the type in some cases, while such reckless indifference should have been displayed