Would it not be worth while to get also some mountain hares for observation at the Zoo? These, I think, I could get. Yours very truly, GEO. J. ROMANES. Geanies, Ross-shire, N.B.: October 15. Would you mind sending me the part of your MS. dealing with Sphex? I do not know that I quite caught your objection to my difficulty, and want to allude to it in lectures which I am now preparing for my Edinburgh class. Also, did I correctly understand you to say that you refused to acknowledge any fundamental identity between processes of reproduction and those of repair? For this identity is to my mind the most important of all objections to W.'s theory. G. J. ROMANES. 18 Cornwall Terrace, Regent's Park, N.W.: December 3, 1889. My dear Poulton,--I returned here a day or two ago, and now send you my copy of Perrier's remarks about the neuters of hymenopterous insects. But he said a good deal more in subsequent and private correspondence. His preface, however, will serve to show you the general tone of argument. With regard to Panmixia, it occurs to me that very likely you have not seen all that I wrote upon it, as the three papers were scattered over several months in 'Nature.' The following are the references: Vol. ix. pp. 361, 440; vol. x. p. 164. You will see that I took up a decided stand upon the principle of Panmixia not being able altogether to supersede that of disuse. This was for the reasons stated in my last letter; and I still see no further reason for changing the opinion that was then formed under the influence of Darwin's judgment. With reference to the difference that you alluded to--and which, as far as I can see, is the only difference between Weismann's presentation of the principle and my own--I enclose an extract from the lecture which I have just been giving in Edinburgh. From this extract I think you will see that the one point of difference does not redound to the credit of Weismann's logic. After reading the extract in conjunction with the papers in 'Nature,' perhaps you will let me know whether you now understand my view any better, or still believe that the cessation of selection _alone_ can reduce the average of a useless organ below fifty per cent, of its original size--so long, that is, as the force of heredity continues unimpaired. G. J. ROMANES. Some further letters to Mr. Thiselton-Dyer and to Mr. F. Darwin follow. _To Professor Thiselton-Dyer._ December 20, 1888. Dear Dyer,--Would you mind sending me on a postcard the name of the genus of plants the constituent species of which you alluded to in the train as being mutually fertile, and also separated from one another topographically? I want to get as many of such cases as I possibly can, so, if any others occur to you, please mention them likewise.