48 INHERITANCE. 



Chap. XIII. 



proper character of trie variety, or its reversion to a former 

 state. 



We have seen in the last section that when two races or 

 species are crossed there is the strongest tendency to the re- 

 appearance in the offspring of long-lost characters, possessed by 

 neither parent nor immediate progenitor. When two white, or 

 red, or black pigeons, of well-established breeds, are united, the 

 offspring are almost sure to inherit the same colours ; but when 

 differently-coloured birds are crossed, the opposed forces of 

 inheritance apparently counteract each other, and the tendency 

 which is inherent in both parents to produce slaty-blue offspring 

 becomes predominant. So it is in several other cases. But 

 when, for instance, the ass is crossed with A. Indicus or with 

 the horse, — animals which have not striped legs, — and the hybrids 

 have conspicuous stripes on their legs and even on their faces, 

 all that can be said is, that an inherent tendency to reversion 

 is evolved through some disturbance in the organisation caused 

 by the act of crossing. 



Another form of reversion is far commoner, indeed is almost 

 universal with the offspring from a cross, namely, to the cha- 

 racters proper to either pure parent-form. As a general rule, 

 crossed offspring in the first generation are nearly intermediate 

 between their parents, but the grandchildren and succeeding 

 generations continually revert, in a greater or lesser degree, 

 to one or both of their progenitors. Several authors have main- 

 tained that hybrids and mongrels include all the characters of 

 both parents, not fused together, but merely mingled in different 

 proportions in different parts of the body; or, as Naudin 48 has 

 expressed it, a hybrid is a living mosaic-work, in which the eye 

 cannot distinguish the discordant elements, so completely are 

 they intermingled. We can hardly doubt that, in a certain sense, 

 this is true, as when we behold in a hybrid the elements of both 

 species segregating themselves into segments in the same flower 

 or fruit, by a process of self-attraction or self-affinity ; this 

 segregation taking place either by seminal or by bud-propagation. 

 Naudin further believes that the segregation of the two specific 

 elements or essences is eminently liable to occur in the male 

 and female reproductive matter ; and he thus explains the almost 

 48 ' Nouvelles Archives du Museum,' torn. i. p. 151. 



