REVERSION, NOT A LAW, SUI GENERIS. 119 



ance of improvements) is also identical with the other 

 . powers of returning to the perfect type : 



"No # doubt the power of reparation, though not 

 always quite perfect, is an admirable provision, ready 

 for various emergencies, even for those which occur 

 only at long intervals of time" (p. 355, Vol. ii). 



In speaking of the power of reproduction of lost 

 members, he says : 



" This power of regrowth does not, however, always 

 act perfectly ; the reproduced tail of a lizard differs in 

 the forms of the scales from the normal tail " (p. 354, 

 Vol. ii). 



So, with the improvements, arising in animals and 

 plants under domestication ; this nisus formativus, this 

 reparative power, or Reversion, — as it is especially 

 so called, when it occurs in a generation following that 

 in which the injury was caused, or the characters were 

 lost, — does not always retrieve, in a complete or perfect 

 state, the characters which were lost by the species. 

 The conditions are not perfectly supplied. When they 

 are perfectly supplied, there will be perfect reparation, 

 perfect reversion, in those animals and plants, as well 

 as in the lizard. 



This "power is greater in animals, the lower they 

 are in the scales of organisms," says Darwin (p. 354, 

 Vol. ii, Animals and Plants, &c). 



The reason of this lessened reproductive power, in 

 the higher animals, is, that such animals are more 

 complex, the conditions of growth are correspondingly 

 more complex, and le.ss easily supplied ; and, therefore, 

 lost members are less likely to be supplied, when 



