(D) I will let the question of Use-Inheritance in relation to seemingly Passive Organs, go by default against me, as it is rather a side issue and would need much writing to discuss. The same applies to your remarks on Teleology. As regards both points I agree with your observations. (E) Touching varieties as found in different areas from parent types, I suppose you heard how carefully Nägeli has gone into the subject, with the result that after making allowances for defects of isolation, change of environment, &c., only about _five per cent. of species of plants seem to have originated on distant areas_, while Wallace has shown that some such proportion applies to animals. (F) As regards plants having been brought under cultivation, and yielding variations that prove heredity, I knew there were innumerable cases where artificial selection had been brought into play. But of course they are all out of court until the question on which you are engaged has been decided in your favour, _i.e._ until you have succeeded in _disproving natural selection_ as analogous or parallel to artificial. It was for this reason I mentioned the case of parsnips, where the hereditary variations seem to have taken place in the _first generation_ after transplanting, and therefore without leaving time for selection of any kind to have come into play. Hôtel Costebelle, Hyères: March 29. Dear Mr. Henslow,--I am still terribly ill and cannot write much. We must have a talk. Could you come to Oxford any day you like and be our guest? I think we might derive mutual benefit. I shall be there from the middle of April till I do not know when. Why not come on May 2, to hear Weismann give his lecture in the afternoon? I much wish you would save seed of any fixed local varieties of plants you may find to be in seed, while you are in Malta (or bulbs), in order to see whether plants grown from them in England will or will not prove fully fertile. This is in relation to my own theory of physiological selection, according to which isolation produces segregation of type; in the same way as it does that of a language--viz. by prevention of intercourse with the parent type and consequently with an independent history of variation. Where the isolation is due to physical barriers (as at Malta) there is no need for any sexual differentiation to originate a species. But on common areas, sexual differentiation is the only means of securing the isolation. Therefore (I say) we can see why Jordan's French varieties all prove sterile with their parent forms, and I should expect your Malta varieties to prove fertile with _theirs_ elsewhere. G. J. R. Costebelle: April 15, 1894.