Dear Darwin,—Will you tell me where are Fleeming Jenkin's arguments on the importance of single variation? Because I at present hold most strongly the contrary opinion, that it is the individual differences or general variability of species that enables them to become modified and adapted to new conditions.
Variations or "sports" may be important in modifying an animal in one direction, as in colour for instance, but how it can possibly work in changes requiring co-ordination of many parts, as in Orchids for example, I cannot conceive. And as all the more important structural modifications of animals and plants imply much co-ordination, it appears to me that the chances are millions to one against individual variations ever coinciding so as to render the required modification possible. However, let me read first what has convinced you.
You may tell Mrs. Darwin that I have now a daughter.
Give my kind regards to her and all your family.—Very truly yours,
ALFRED R. WALLACE.
Down, Bromley, Kent, S.E. February 2, 1869.
My dear Wallace,—I must have expressed myself atrociously; I meant to say exactly the reverse of what you have understood. F. Jenkin argued in the North British Review[77] against single variations ever being perpetuated, and has convinced me, though not in quite so broad a manner as here put. I always thought individual differences more important, but I was blind and thought that single variations might be preserved much oftener than I now see is possible or probable. I mentioned this in my former note merely because I believed that you had come to similar [pg 235]conclusions, and I like much to be in accord with you. I believe I was mainly deceived by single variations offering such simple illustrations, as when man selects.
We heartily congratulate you on the birth of your little daughter.—Yours very sincerely,
C. DARWIN.