Russel Wallace : Alfred Russell Wallace (sic)
The point at issue is, whether "individual differences" (in other words, fluctuating variations) or "single variations" (the equivalent of "sports" or "mutations") are the main, or even exclusive, factors in the origin of species. Darwin and myself held the former; the mutationists and Professor Hubrecht hold the latter.
Darwin wrote in 1869 (after having been elaborating his theory for thirty years): "I have always thought individual differences more important than single variations." And in his "Animals and Plants under Domestication" (Vol. II., p. 192), published in 1868, before the correspondence with myself on the subject, he says--speaking of the power of Selection, whether by man or nature--"Slight individual differences, however, suffice for the work, and are probably the sole differences which are effective in the production of new species."
Yet in face of these two positive statements (noting especially the words I have italicised) Professor Hubrecht has the boldness to declare that "if Darwin in his later years allowed himself to side with Wallace and others to an increasing extent, this does not diminish the right of modern biologists to stick to Darwin's earlier views."
What are these "earlier views" and where are they to be found? In the "Origin of Species" are numerous references to the same point, though often less definitely expressed. Thus, at p. 47 of the 4th edition, published before Fleming Jenkin's criticism, he says: "It may be doubted whether sudden and great variations . . . are ever permanently propagated in a state of nature"; and the whole succeeding section on "Individual Differences" is to the same [[p. 717]] purport. Again, at p. 93 of the same edition, referring to slow physical and organic changes of the environment, he says: "In such cases, every slight modification which in any way favoured the individuals of any of the species . . . would tend to be preserved." And again, at p. 95: "It may metaphorically be said that natural selection is daily and hourly scrutinising, throughout the world, every variation, even the slightest; rejecting that which is bad, preserving and adding up all that is good."
These passages are sufficient to show that there had been no "earlier views" from which Darwin later on diverged in consequence of Fleming Jenkin's review and my altogether imaginary influence, except that, latterly, from supposing that "single variations" might occasionally serve to initiate new species, he came to see that this was so improbable as to be a negligible factor in natural selection--he had been before, as he says, "blind" to the difficulties. During the whole of Darwin's life I can safely say that there was absolutely no difference whatever between Darwin's views and my own on this subject. It is only the immense accumulation of facts during the last quarter of a century, both as to the amount and universality of "individual variations," and as to the extreme rigidity of "natural selection," that has led most Darwinians as well as myself to go one step farther than Darwin was able to do, and to doubt whether "single variations" ever originated a natural "species."
I leave Professor Hubrecht to bring forward the evidence of those "earlier views" of Darwin's which he has claimed to exist, or, failing that, to make such an apology as seems to him proper for having so prominently asserted an antagonism between Darwin and myself which had no existence whatever.