Yours very truly,
G. J. Romanes.
Geanies, Ross-shire, N.B.: November 11, 1889.
My dear Poulton,—Although I spent more time and trouble than I like to acknowledge (even to myself) in trying to prove Pangenesis between '73 and '80, I never obtained any positive results, and did not care to publish negative. Therefore there are no papers of mine on the subject, although I may fairly believe that no other human being has tried so many experiments upon it. No doubt you will think that I ought to regard this fact as so much negative evidence in favour of the new theory; and, up to a certain point, I do, only the issue between Pangenesis and Germ-plasm is not really or nearly so well defined as Weismann represents, where the matter of experiments is concerned; e.g. it is not the case that any crucial test is furnished by the non-transmissibility of mutilations; Darwin did not set much store by them, though Eimer and others have done so since. In fact all the Germans on both sides, and all the Englishmen on Weismann's side, seem to me unjust to Darwin in this respect.
Regarding the cessation of selection, the motive that prompted my question to you was not the paltry one of claiming priority in the enunciation of an exceedingly obvious idea. My motive was to assure myself that this idea is exactly the same as Weismann's Panmixia; for, although I could see no difference, I thought perhaps he and you did (from absence of allusion to my paper, while priority is acknowledged as regards a later one); and, if this were so, I wanted to know where the difference lay. And the reason I wanted to know this was because when my paper was published, and Darwin accepted the idea with enthusiasm, I put it to him in conversation whether this idea might not supersede Lamarckian principles altogether. (By carefully reading between the lines of the paper itself, you will see how much this question was occupying my mind at the time, though I did not dare to challenge Lamarck's principles in toto without much more full inquiry.) Then it was that Darwin dissuaded me from going on to this point, on the ground that there was abundant evidence of Lamarck's principles apart from use and disuse of structures—e.g. instincts—and also on the ground of his theory of Pangenesis. Therefore I abandoned the matter, and still retain what may thus be now a prejudice against exactly the same line of thought as Darwin talked me out of in 1873. Weismann, of course, has greatly elaborated this line of thought; but what may be called the scientific axis of it (viz. possible non-inheritance of acquired characters) is identical, and all the more metaphysical part of it about the immortality, immutability, &c., of a hypothetical germ-plasm is the weakest part in my estimation.
Now, the point I am working up to is this. If there be no difference between Panmixia and Cessation of Selection, from what I have briefly sketched about it, it follows that, had Darwin lived till now, he would almost certainly have been opposed to Weismann. This is not a thing I should like to say in public, but one that I should like to feel practically assured about in my own mind.
Regarding the numerical calculations, I have not got a copy of the 'Nature' paper here, but, so far as I remember (and I think I am right), the idea was that 'Economy of Growth' would go on assisting Cessation of Selection till the degenerating organ became 'rudimentary.' In other words, reversal of selection would co-operate with cessation of it.
This, as I understand it, is now exactly Weismann's view; only he thinks that thus the rudimentary organ would finally become extinguished. Here, however, it seems to me evident he must be wrong. The reasons are obvious, as I am going to show this week to my Edinburgh class. Six lectures are to be devoted entirely to Weismann, and when they are published (as they will be this time next year), I think it will be seen that Weismannism is not such very plain sailing as Weismann himself seems to think. Vines has anticipated some of my points in his paper in 'Nature'; but I hope this may have the effect of letting me see what answers can be given before I shall have to publish.
Yours very truly,
G. J. Romanes.