HIGHLY VARIABLE. 145 



manner and degree, and by the continued rejection of those 

 tending to revert to a former and less modified condition. 



SPECIFIC CHARACTERS MORE VARIABLE THAN" GENERIC 

 CHARACTERS. 



The principle discussed under the last heading may be 

 applied to our present subject. It is notorious that spe- 

 cific characters are more variable than generic. To ex- 

 plain by a simple example what is meant: if in a large 

 genus of plants some species had blue flowers and some 

 had red, the color would be only a specific character, atid 

 no one would be surprised at one of the blue species vary- 

 ing into red, or conversely; but if all the species had blue 

 flowers, the color would become a generic character, and 

 its variation would be a more unusual circumstance. I 

 have chosen this example because the explanation which 

 most naturalists would advance is not here applicable, 

 namely, that specific characters are more variable than gen- 

 eric, because they are taken from parts of less physiological 

 importance than those commonly used for classing genera. 

 I believe this explanation is partly, yet only indirectly, 

 true; I shall, however, have to return to this point in the 

 chapter on Classification. It would be almost superfluous 

 to adduce evidence in support of the statement, that ordi- 

 nary specific characters are more variable than generic: 

 but with respect to important characters, I have repeatedly 

 noticed in works on natural history, that when an author 

 remarks with surprise that some important organ or part, 

 which is generally very constant throughout a large group 

 of species, differs considerably in closely allied species, it is 

 often variable in the individuals of the same species. And 

 this fact shows that a character, which is generally of gen- 

 eric value, when it sinks in value and becomes only of spe- 

 cific value, often becomes variable, though its physiological 

 importance may remain the same. Something of the same 

 kind applies to monstrosities: at least Is. Geoffroy St. 

 Hilaire apparently entertains no doubt, that the more an 

 organ normally difi'ers in the different species of the same 

 group, the more subject it is to anomalies in the individ- 

 uals. 



On the ordinary view of each species having been inde- 



