our pictures; they can, however, generally find space for a picture if they want to hang it, and we assume with safety that there are no master-works by painters of the very highest rank for which no space has been available. Want of space will, indeed, prevent my quoting from more than one other paragraph of Mr. Darwin’s introduction; this paragraph, however, should alone suffice to show how inaccurate Mr. Allen is in saying that Mr. Darwin “laid no sort of claim to originality or proprietorship” in the theory of descent with modification, and this is the point with which we are immediately concerned. Mr. Darwin says:— “In considering the origin of species, it is quite conceivable that a naturalist, reflecting on the mutual affinities of organic beings, on their embryological relations, their geographical distribution, geological succession, and other such facts, might come to the conclusion that each species had not been independently created, but had descended like varieties from other species.” It will be observed that not only is no hint given here that descent with modification was a theory which, though unknown to the general public, had been occupying the attention of biologists for a hundred years and more, but it is distinctly implied that this was not the case. When Mr. Darwin said it was “conceivable that a naturalist might” arrive at the theory of descent, straightforward readers took him to mean that though this was conceivable, it had never, to Mr. Darwin’s knowledge, been done. If we had a notion that we had already vaguely heard of the theory that men and the lower animals were descended from common ancestors, we must have been wrong; it was not this that we had heard of, but something else, which, though doubtless a little like it, was all wrong, whereas this was obviously going to be all right. To follow the rest of the paragraph with the closeness that it merits would be a task at once so long and so unpleasant that I will omit further reference to any part of it except the last sentence. That sentence runs:— “In the case of the mistletoe, which draws its nourishment from certain trees, which has seeds that must be transported by certain birds, and which has flowers with separate sexes absolutely requiring the agency of certain insects to bring pollen from one flower to the other, it is equally preposterous to account for the structure of this parasite, with its relations to several distinct organic beings, by the effects of the external conditions, or of habit, or of the volition of the plant itself.”