Characters as Adaptive and Specific. 229 



variations that are not inherited. And the same 

 remark applies to all the other cases which have been 

 adduced to show the generality and extent of climatic 

 variation, both in other animals and also in plants. 

 Why, then, it will be asked, commit the absurdity of 

 adducing such cases in the present discussion ? Is it 

 not self-evident that however general, or however 

 considerable, such merely individual, or non-heritable, 

 variations may be, they cannot possibly have ever had 

 anything to do with the origin of species ? Therefore, is 

 it not simply preposterous to so much as mention 

 them in relation to the question touching the utility 

 of specific characters? 



Well, whether or not it is absurd and preposterous 

 to consider climatic variations in connexion with the 

 origin of species, will depend, and depend exclusively, 

 on what it is that we are to understand by a species. 

 Hitherto I have assumed, for the sake of argument, 

 that we all know what is meant by a species. But 

 the time has now come for showing that such is far 

 from being the case. And as it would be clearly 

 absurd and preposterous to conclude anything with 

 regard to specific characters before agreeing upon 

 what we mean by a character as specific, I will 

 begin by giving all the logically possible definitions 

 of a species. 



i . A group of individuals descended by way of natural 

 generation from an originally and specially created type. 



This definition may be taken as virtually obsolete. 



Q,. A group of individuals which, while fully fertile 

 inter se, are sterile with all other individuals or, at 

 any rate, do not generate fully fertile hybrids. 



This purely physiological definition is not nowadays 



