114 SPECIFIC CHARACTERS [CHAP. V. 



Specific CJiaracters more Variable titan 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 surprised at one of the blue 

 species varying into red, or conversely ; 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 example because the explanation which most natural- 

 ists would advance is not here applicable, namely, that specific 

 characters are more variable than generic, 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 

 ordinary specific characters are more variable than generic ; but 

 \vith 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 con- 

 siderably 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 generic value, when it sinks in 

 value and becomes only of specific value, often becomes variable, 

 though its physiological importance may remain the same. 

 Something of the same kind applies to monstrosities : at least 

 Is. Geoffrey St. Hilaire apparently entertains no doubt, that the 

 more an organ normally differs in the different species of the same 

 group, the more subject it is to anomalies in the individuals. 



On the ordinary view of each species having been independently 

 created, why should that part of the structure, which differs from 

 the same part in other independently -created species of the same 

 genus, be more variable than those parts which are closely alike 

 in the several species? I do not see that any explanation can be 

 given. But on the view that species are only strongly marked 

 and fixed varieties, we might expect often to find them still 

 continuing to vary in those parts of their structure which have 

 varied within a moderately recent period, and which have thus 

 come to differ. Or to state the case in another manner : the 

 points in which all the species of a genus resemble each other, 

 and in which they differ from allied genera, are called generic 

 characters ; and these characters may be attributed to inheritance 



