constructed on the ideal pattern that was devised for the cuttle-fish? Of course it may be answered that perhaps there was some hidden reason why the design should never have allowed an adaptation which it had devised for one division of organic nature to appear in another--even in cases where the new design necessitated the closest possible resemblance in everything else, save in the matter of anatomical homology. Undoubtedly such may have been the case--or rather such _must_ have been the case--if the theory of special design is true. But where the question is as to the truth of this theory, I think there can be no doubt that its rival gains an enormous advantage by being able to _explain_ why the facts are such as they are instead of being obliged to take refuge in hypothetical possibilities of a confessedly unsubstantiated and apparently unsubstantial kind. Therefore, as far as this objection to the theory of natural selection is concerned--or the allegation that homologous structures occur in different divisions of organic nature--not only does it fall to the ground, but positively becomes itself converted into one of the strongest arguments in favour of the theory. As soon as the allegation is found to be baseless, the very fact that it cannot be brought to bear upon any one of all the millions of adaptive structures in organic nature becomes a fact of vast significance on the opposite side. * * * * * The next difficulty to which I shall allude is that of explaining by the theory of natural selection the preservation of the first beginnings of structures which are then useless, though afterwards, when more fully developed, they become useful. For it belongs to the very essence of the theory of natural selection, that a structure must be supposed already useful before it can come under the influence of natural selection: therefore the theory seems incapable of explaining the origin and conservation of _incipient_ organs, or organs which are not yet sufficiently developed to be of any service to the organisms presenting them. This objection is one that has been advanced by all the critics of Darwinism; but has been presented with most ability and force by the Duke of Argyll. I will therefore state it in his words.