I am disposed to join issue with you on the question of Linnæus’ definition of species. I have long pondered your discussion of the subject in “Géographie Botanique,” and still think, on the supposition of the fixity of species (which Linnæus of course had in view), that between “community of descent” and “likeness,” the former and not the latter is the fundamental conception in the idea of species. We may test this by inquiring whether of the two can be derived from the other. The likeness, I suppose, is the consequence of the community of descent. But, then, as the likeness is a thing of degrees, and, according to present probabilities, species may have only a relative and temporary fixity, your view will after all have the advantage; and the question of species will come to be metaphysical or logical, rather than natural-historical. The worst of all is that there will remain no objective basis or standard; and species will be what each naturalist thinks best so to consider! I am pleased to know that the view of my article on the “Memoirs”[53] is well received by you. Readable articles are very needful, when they can be had, for a journal which, like Silliman’s, cannot exist without popular support. I promised an article of sixteen pages of this character; but I intended to enlarge more at the close upon the genius and influence of your father, and cite your parallel with Linnæus as portrayed by Fabricius. But I found that my pages were filled before I was aware of it, and I had to cut short, much too curtly. It left me with a somehow dissatisfied feeling. All your remarks about the difference between the profound and the prolific botanists, I agree to; and I think that both Linnæus and De Candolle had as much genius as Robert Brown.... Well, as to origin of species, you have now gone just about as far as I have, in Darwinian direction, and both of us have been led step by step by the facts and probabilities, and have not jumped at conclusions. I shall be curious to see Mme. Royer’s book; Darwin has spoken of her. Under my hearty congratulations of Darwin for his striking contributions to teleology, there is a vein of petite malice, from my knowing well that he rejects the idea of design, while all the while he is bringing out the neatest illustrations of it! Did time allow, I should like to write at large upon these enticing topics.... TO W. J. HOOKER. CAMBRIDGE, March 16, 1863. I received this morning a letter from William Short, announcing to me the death of his lamented father, our excellent friend, Dr. C. W. Short, of Louisville, Kentucky, one of our oldest botanists, and one of the best of men and kindest of friends. He died on the 7th inst., of a typhoid fever, supervening on a severe cold. I feel the loss very much. Although we never met, he was one of my most valued friends....