CHAPTER III. 



SPECIES, LINNEONS, GENERA AND OTHER „HIGHER 

 GROUPS" AND EVOLUTION. 



The problem of Evolution is not, primarily, as is al- 

 most generally believed, the problem of the origin of 

 species, but is the problem of the origin of all those in- 

 dividuals of different constitution, which people the 

 earth. 



Of some of these individuals we can make clear-cut 

 definable groups, by uniting those monogametic indi- 

 viduals which are constitutionally identical, to groups 

 which we may call species, and explain how such spe- 

 cies can arise. 



But when we find, as we do, that such species are 

 very rare in nature, we recognize that the problem set 

 to the evolutionist is not limited to the origin of these 

 pure species which are but rarely or never met with 

 in nature, but embraces the problem of that vastly 

 greater number of impure individuals by which the 

 earth is peopled. , •; 



The problem of the species and of its origin is conse- 

 quently comparable to that of the pure chemical substance 

 and its origin, the problem of the heterozygotes of diffe- 

 rent constitutions which we find in nature and of their 

 origin is comparable to the problem of the ores found in 

 nature and their origin. Now to gain a good insight 

 in the first part which we might call the chemical side 



