Chap. XIII. REVERSION. 25 



author on the tendency to reversion in all hybrids. The con- 

 clusion that the condition of the parent-species, as affected by 

 culture, is one of the proximate causes leading to reversion, 

 agrees well with the converse case of domesticated animals and 

 cultivated plants being liable to reversion when they become 

 feral ; for in both cases the organisation or constitution must 

 be disturbed, though in a very different way. 53 



Finally, we have seen that characters often reappear in 

 purely-bred" races without our being able to assign any 

 proximate cause ; but when they become feral this is either 

 indirectly or directly induced by the change in their condi- 

 tions of life. With crossed breeds, the act of crossing in 

 itself certainly leads to the recovery of long-lost characters, 

 as well as of those derived from either parent-form. Changed 

 conditions, consequent on cultivation, and the relative position 

 of buds, flowers, and seeds on the plant, all apparently aid in 

 giving this same tendency. Eeversion may occur either 

 through seminal or bud generation, generally at birth, but 

 sometimes only with an advance of age. Segments or portions 

 of the individual may aloue be thus affected. That a being 

 should be born resembling in certain characters an ancestor 

 removed by two or three, and in some cases by hundreds or 

 even thousands of generations, is assuredly a wonderful fact. 

 In these cases the child is commonly said to inherit such 

 characters directly from its grandparent, or more remote 

 ancestors. But this view is hardly conceivable. If, however, 

 we suppose that every character is derived exclusively from 

 the father or mother, but that many characters lie latent or 

 dormant in both parents during a long succession of genera- 

 tions, the foregoing facts are intelligible. In what manner 

 characters may be conceived to lie latent, will be considered 

 in a future chapter to which I have lately alluded. 



Latent Characters. — But I must explain what is meant by 



53 Prof. Weismann, in his very elusion, namely, that any cause which 



curious essay on the different forms disturbs the organisation, such as the 



produced by the same species of exposure of the cocoons to heat or 



butterfly at different seasons (' Saison- even to much shaking, gives a 



Dimorphismus der Schmetterlinge,' pp. tendency to reversion. 

 27, 28), has come to a similar con- 



