VARIATIONS, DUE TO REVERSION. 49 



tions, or improvements, may go on forever, or indefi- 

 nitely; and shows that there exists a limit, within each 

 species, to the amount of improvement of which its 

 individuals are susceptible. 



Darwin, in treating of this law of reversion, ascribes 

 to it the appearance of nearly every improvement under 

 domestication. Almost every character, and organ, 

 which has been developed, under man's care, and 

 ■ those which have arisen induced only by the presence 

 of favorable conditions of growth, he says, were once 

 in some period past, in a perfect state, and fully devel- 

 oped in some remote ancestor; that, owing to adverse 

 conditions, under nature, those characters and organs 

 had become either wholly lost, or partially reduced; 

 that those characters and organs lay latent, during the 

 long interval, ready ever to be evolved again, whenever 

 the favorable conditions, essential to their growth, were 

 restored; and that their reappearance, under domesti- 

 cation, is due to this capacity of reversion, which resides 

 in every individual whose structure has been impaired. 

 Almost every feature, which has appeared under domes- 

 tication, he, in detail, ascribes to the mere reappearance 

 of some character, once lost by an ancient progenitor. 

 So widespread, he asserts, has been the degeneration 

 under nature, that there exists scarcely a single species 

 which has not lost some organs or features. He asserts 

 that characters which have been lost, may lie in the 

 organisms, either in a rudimentary state, or with not a 

 trace of them discernible; and do so lie, for thousands 

 and millions of generations, with their power of rever- 

 sion, or of re-development, undiminished; that, when 

 5* 



