THE EVOLUTION OF LIVING BEINGS. 43 



of the problem, it was highly desirable to make groups 

 of indentical individuals and to name these groups: 

 species, because by so reducing the number of cases 

 with which we have to deal, we simplified matters 

 without impairing the exactness of the investigation 

 in the least. 



The question becomes different, when we proceed to 

 unite the impure forms found in nature, to groups of 

 similar, but not identical individuals because, by 

 doing this, we only seem to simplify the problem while, 

 in fact, we complicate it and impair seriously the exact- 

 ness of our investigation. 



We impair the exactness of our investgation becau- 

 se we form groups which are undefinable, and in so 

 doing, open the door to different opinions, as to which 

 individuals should be received into such groups. That- 

 as everybody knows causes great trouble in fixing the 

 limits of such groups as Linneons, Genera, Families, 

 Classes etc. But what is far worse, forgetting the nature 

 of these divisions, we are unconsciously and gradually 

 led to believe — as generally is believed — that such 

 groups, which we call higher groups 1 ), have necessa- 

 rily as real an existence as species have, and that con- 

 sequently, their origin must be explained as an origin 

 of entities also, while, in fact, they may have no real 

 existence at all, but exist in our imagination only. 



Sixty years ago already, Jordan has, in a discussion 

 with de Candolle, laid stress on the basic difference 

 between a species as an entity and a Linneon (which he 



*) It were better to speak of larger groups. 



