FERTILITY BETWEEN DOMESTIC RACES 83 



to speak or write on the broader aspects of biological 

 inquiry. 1 



Darwin also considered that there was something in 

 the very conditions of domestication which tended to 

 promote fertility between races and even between distinct 

 species. Thus he followed Pallas in believing that the 

 domestic dog has been derived from more than one wild 

 species, although he did not trace existing differences to 

 this cause but to Artificial Selection. 2 However, as re- 

 gards the origin of the dog, ' the evidence is, and must 

 be, very doubtful,' as he wrote to Lyell, August 11, 

 [i860]. The fact which Darwin 'considered the most 

 remarkable as yet recorded with respect to the fertility 

 of hybrids ' was the fertility of the offspring of the 

 Common and Chinese Goose, originally described by 

 Eyton, and confirmed by Goodacre and by Darwin 

 himself. ' The two species of goose now shown to 

 be fertile inter se are so distinct that they have 

 been placed by some authorities in distinct genera or 

 sub-genera.' 3 



Another interesting and exceedingly difficult experi- 

 ment in hybridization has been carried through by the 

 Rev. P. St. M. Podmore, F.Z.S., who in September, 

 1899, after numerous failures, succeeded in rearing a 

 healthy male hybrid between the Ring Dove (Columba 

 palumbtcs) and the domestic pigeon. On May 27, 1903, 



1 For several instances see Poulton's Charles Darwin and the Theory 

 of Natural Selection, Lond. 1896, pp. 124-41. 



• ' Though I believe that our domestic dogs have descended from 

 several wild forms, and though I must think that the sterility, which they 

 would probably have evinced, if crossed before being domesticated, has 

 been eliminated, yet I go but a very little way with Pallas & Co. in 

 their belief in the importance of the crossing and blending of the 

 aboriginal stocks. . . . Although the hound, greyhound, and bull-dog may 

 possibly have descended from three distinct stocks, I am convinced that 

 their present great amount of difference is mainly due to the same causes 

 [Artificial Selection] which have made the breeds of pigeons so different 

 from each other, though these breeds of pigeons have all descended from 

 one wild stock ; so that the Pallasian doctrine I look at as but of quite 

 secondary importance.' More Letters, vol. i, pp. 127, 128, Letter 80, 

 to Lyell, October 31, [1859]. 



3 Life and Letters, vol. iii, p. 240. 



G 2 



