XXIV GENERAL INTRODUCTION. 



as he devoted his attention chiefly to the coloration of 

 the species. It seems to me to be very probable, how- 

 ever, from several of his statements, that this was also 

 essentially a mere case of reversion as regards the colora- 

 tion of the plumage. . . . The other racial characteristics 

 do not at any rate exclude the possibility of a blue colora- 

 tion ; and thus, on the other hand, reversion to the 

 blue colour is not necessarily accompanied by a reversion 

 to all the other characters of the ancestral form."* I 

 think, though Darwin does not definitely make the asser- 

 tion, almost complete reversion in his barb-fantail-spot 

 cross is implied. Had this cross in its beak or legs, or 

 length of wings, differed decidedly from the wild rock 

 standard, the fact would most probably have been men- 

 tioned. 



Whatever uncertainty remains as to the extent of re- 

 version in pigeons should, however, be dispelled. It is 

 partly with this object in view, and partly to throw new 

 light on inbreeding and prepotency, that I have recently 

 been experimenting with pigeons. Darwin, when dis- 

 cussing prepotency in the pigeon group, says, " In making 

 reciprocal crosses between pouters and fantail pigeons 

 [i. e. crossing them both ways] the pouter race seemed to 

 be prepotent through both sexes over the fantail. But 

 this is probably due to weak power in the fantail, rather 

 than unusually strong power in the pouter ; for I have 

 observed that barbs also preponderate over fantails.^'t 

 But not only are some varieties said to be more prepotent 

 than others, it is generally assumed that certain colours 

 and markings are latent, and ever ready when there is 

 any disturbance of the balance to reassert themselves. 

 To use Mr. Wicking's words, " when a blue or a black 

 and chequered bird, having black wing bars, once appears 

 in any race and is allowed to breed, these characters are 

 so strongly transmitted that it is extremely difficult to 

 eradicate them." J 



* ' Germ-plasm,' pp. 323, 324. 

 •j- ' Animals and Plants,' vol. ii, p. 41. 

 ■ + Ibid.,' vol. i, p. 210. 



