164 ORIGIN OF SPECIES 



cease; and that the most abnormally developed organs may 

 be made constant, I see no reason to doubt. Hence, when 

 an organ, however abnormal it may be, has been transmitted 

 in approximately the same condition to many modified de- 

 scendants, as in the case of the wing of the bat, it must have 

 existed, according to our theory, for an immense period in 

 nearly the same state; and thus it has come not to be more 

 variable than any other structure. It is only in those cases 

 in which the modification has been comparatively recent and 

 extraordinarily great that we ought to find the generative 

 variability, as it may be called, still present in a high degree. 

 For in this case the variability will seldom as yet have been 

 fixed by the continued selection of the individuals varying 

 in the required 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 specific 

 characters are more variable than generic. To explain by a 

 simple example what is meant: if in a large genus of plants 

 some species had blue flowers and some had red, the colour 

 would be only a specific character, and no one would be sur- 

 prised at one of the blue species varying into red, or con- 

 versely; but if all the species had blue flowers, the colour 

 would become a generic character, and its variation would 

 be a more unusual circumstance. I have chosen this exam- 

 ple because the explanation which most naturalists would 

 advance is not here applicable, namely, that specific charac- 

 ters are more variable than generic, because they are taken 

 from parts of less physiological importance than those com- 

 monly 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 ordinary specific characters are more variable 

 than generic; but with respect to important characters, I 



