ON THE ORIGIN OF GENERA. 123 



in other words, that while nature's series have been projected in 

 accordance with the hiw of acceleration and retardation, they have 

 been limited, modified, and terminated by the law of natural se- 

 lection, which may itself have operated in part by the same law. 



III. The processes of development of specific and generic, char- 

 acters have not proceeded pari passu, transitions of the one kind 

 not being synchronous with transitions of the other ; and that, 

 therefore, species may be transferred from one genus to another 

 without losing their specific characters, and genera from order to 

 order without losing their generic characters. 



IV. And as the heterologous terms of the peculiar homologous 

 groups present an ^^ inexact parallelism" with each other; and 

 as types related by inexact parallelism are each among themselves 

 exact parallels in separate series, whose earliest members present 

 *^ exact parallelisms " with each other, it follows — 



Y. That the heterologous terms or genera in the later series 

 are modified descendants of those of the earlier series ; in other 

 words, that certain groups higher than genera are produced from 

 others of similar high value by "descent with modification." 



YI. That the result of such successional metamorphoses will 

 be expressed in geologic history by more or less abrupt transitions 

 or expression-points, rather than by uniformly gradual succes- 

 sions. 



Of course, under the conclusion stated in Proposition II, the 

 genus Homo has been developed by the modification of some pre- 

 existent genus. All his traits which are merely functional have, 

 as a consequence, been produced during the process. Those traits 

 which are not functional, but spiritual, are of course amenable to 

 a different class of laws, which belong to the province of religion. 



