Chap. XIV. PREPOTENCY OF TRANSMISSION. 45 



that a purely-bred form of either sex, in all cases in which 

 prepotency does not run more strongly in one sex than the 

 other, will transmit its character with prej)otent force over 

 a mongrelised and already variable form.' 21 From several of 

 the above-given cases we may conclude that mere antiquity 

 of character does not by any means necessarily make it pre- 

 potent. In some cases prepotency apparently depends on the 

 same character being present and visible in one of the two 

 breeds which are crossed, and latent or invisible in the other 

 breed ; and in this case it is natural that the character which 

 is potentially present in both breeds should be prepotent. 

 Thus, we have reason to believe that there is a latent ten- 

 dency in all horses to be dun-coloured and striped ; and 

 when a horse of this kind is crossed with one of any other 

 colour, it is said that the offspring are almost sure to be 

 striped. Sheep have a similar latent tendency to become 

 dark-coloured, and we have seen with what prepotent force 

 a ram with a few black spots, when crossed with white sheep 

 of various breeds, coloured its offspring. All pigeons have a 

 latent tendency to become slaty-blue, with certain character- 

 istic marks, and it is known that, when a bird thus coloured 

 is crossed with one of any other colour, it is most difficult 

 afterwards to eradicate the blue tint. A nearly parallel case 

 is offered by those black bantams which, as they grow old, 

 develope a latent tendency to acquire red feathers. But 

 there are exceptions to the rule : hornless breeds of cattle 

 possess a latent capacity to reproduce horns, yet when crossed 

 with horned breeds they do not invariably produce offspring- 

 bearing horns. 



We meet with analogous cases with plants. Striped flowers, 

 though they can be propagated truly by seed, have a latent 

 tendency to become uniformly coloured, but when once crossed 

 by a uniformly coloured variety, they ever afterwards fail to 



21 See some remarks on this head between English and French sheep, 



with respect to sheep by Mr. Wilson, He found that he obtained the 



in ' Gardener's Chronicle,' 1863, p. 15. desired influence of the English breeds 



Many striking instances of this result by crossing intentionally mongrelised 



are given by M. Malingie-Nouel French breeds with pure English 



(' Journ. R. Agricult. Soc.,' vol. xiv. breeds. 

 1853, p. 220) with respect to crosses 



