Chap. XIV. 



PREPOTENCY OF TRANSMISSION, 



69 



mitted in an unmodified state from either parent-form ; I refer to this 

 fact here because it is sometimes accompanied on the one side by prepotency, 

 which thus acquires the false appearance of unusual strength. In the 

 same chapter I shall show that the rate at which a species or breed absorbs 

 and obliterates another by repeated crosses, depends in chief part on pre- 

 potency in transmission. 



In conclusion, some of the cases above given, — for instance, 

 that of the trumpeter pigeon, — prove that there is a wide dif- 

 ference between mere inheritance and prepotency. This latter 

 power seems to us, in our ignorance, to act in most cases quite 

 capriciously. The very same character, even though it be 

 an abnormal or monstrous one, such as silky feathers, may be 

 transmitted by different species, when crossed, either with 

 prepotent force or singular feebleness. It is obvious, 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 prepotent force over a mongrelized 

 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 prepotent. In 

 some cases prepotency apparently depends on the same cha- 

 racter 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 poten- 

 tially present in both should be prepotent. Thus, we have 

 reason to believe that there is a latent tendency 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 off- 

 spring 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 

 characteristic marks, and it is known that, when a bird thus 

 coloured is crossed with one of any other colour, it is most diffi- 

 cult afterwards to eradicate the blue tint. A nearly parallel 

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



21 See some remarks on this head with respect to sheep bv Mr Wilson «« 

 ' Gardner's Chronicle,' 1863, p. 15. ' ' 



