Chap. VII. REVERSION AND ANALOGOUS VARIATION. 239 



not quite overlook, though we must not exaggerate, the import- 

 ance of the test of fertility. Most of our domestic breeds have 

 been so often crossed, and their mongrels so largely kept, that 

 it is almost certain, if any degree of infertility had existed 

 between them, it would have been detected. On the other 

 hand, the four known species of Gallus when crossed with each 

 other, or when crossed, with the exception of G. banhiva, with the 

 domestic fowl, produce infertile hybrids. 



Finally, we have not such good evidence with fowls as with 

 pigeons, of all the breeds having descended from a single primi- 

 tive stock. In both cases the argument of fertility must go for 

 something; in both we have the improbability of man having 

 succeeded in ancient times in thoroughly domesticating several 

 supposed species, — most of these supposed species being ex- 

 tremely abnormal as compared with their natural allies, — 

 all being now either unknown or extinct, though the parent- 

 form of scarcely any other domesticated bird has been lost. 

 But in searching for the supposed parent-stocks of the various 

 breeds of the pigeon, we were enabled to confine our search 

 to species having peculiar habits of life ; whilst with fowls there 

 is nothing in their habits in any marked manner distinct from 

 those of other. gallinaceous birds. In the case of pigeons, I have 

 shown that purely-bred birds of every race and the crossed 

 offspring of distinct races frequently resemble, or revert to, the 

 wild rock-pigeon in general colour and in each characteristic 

 mark. With fowls we have facts of a similar nature, but less 

 strongly pronounced, which we will now discuss. 



Reversion and Analogous Variation.— Purely-bred Game, Malay, 

 Cochin, Dorking, Bantam, and, as I hear from Mr. Tegetmeier, 

 Silk fowls, may frequently or occasionally be met with, which 

 are almost identical in plumage with the wild G, banhiva. This 

 is a fact well deserving attention, when we reflect that these 

 breeds rank amongst the most distinct. Fowls thus coloured 

 are called by amateurs black-breasted reds. Hamburghs pro- 

 perly have a very different plumage; nevertheless, as Mr. 

 Tegetmeier informs me, " the great difficulty in breeding cocks 

 of the golden-spangled variety is their tendency to have black 

 breasts and red backs." The males of white Bantams and 



