Dear Sir,--Darwin believed that all living things originated from "a few forms or from one"--as stated in the last sentence of his "Origin of Species." But privately I am sure he believed in the _one_ origin. Of course there is a possibility that there were several distinct origins from inorganic matter, but that is very improbable, because in that case we should expect to find some difference in the earliest forms of the germs of life. But there is no such difference, the primitive germ-cells of man, fish or oyster being almost indistinguishable, formed of identical matter and going through identical primitive changes. As to the humming-bird and hippopotamus, there is no doubt whatever of a common origin--if evolution is accepted at all; since both are vertebrates--a very high type of organism whose ancestral forms can be traced back to a simple type much earlier than the common origin of mammals, birds and reptiles.--Yours very truly, ALFRED R. WALLACE. * * * * * TO SIR FRANCIS DARWIN _Parkstone, Dorset. July 3, 1901._ Dear Mr. Darwin,--Thanks for the letter returned. I _do_ hold the opinion expressed in the last sentence of the article you refer to, and have reprinted it in my volume of Studies, etc. But the stress must be laid on the word _proof_. I intended it to enforce the somewhat similar opinion of your father, in the "Origin" (p. 424, 6th Edit.), where he says, "Analogy may be a deceitful guide." But I really do not go so far as he did. For he maintained that there was not any proof that the several great classes or kingdoms were descended from common ancestors. I maintain, on the contrary, that all without exception are now proved to have originated by "descent with modification," but that there is no proof, and no necessity, that the very same causes which have been sufficient to produce all the species of a genus or Order were those which initiated and developed the greater differences. At the same time I do _not_ say they were not sufficient. I merely urge that there is a difference between proof and probability.--Yours very truly, ALFRED R. WALLACE. * * * * * TO PROF. POULTON _Broadstone, Wimborne. August 5, 1904._ My dear Poulton,-- ... What a miserable abortion of a theory is "Mutation," which the Americans now seem to be taking up in place of Lamarckism, "superseded." Anything rather than Darwinism! I am glad Dr. F.A. Dixey shows it up so well in this week's _Nature_,[30] but too mildly!--Yours very truly, ALFRED R. WALLACE. * * * * * TO PROF. POULTON _Broadstone, Wimborne. April 3, 1905._