THE THEORY OF MUTATIONS 95 



get a stage or two further and try to separate the 

 various members of the families Rubus or Salix 

 from one another, we find ourselves in what seems 

 to be inextricable confusion, unless perchance 

 one is gifted with the peculiar kind of mind be- 

 longing to the person sometimes unkindly called 

 a " species-monger." At any rate botanists, at 

 least, seem to have arrived at the opinion that 

 amongst the groups commonly called " varieties " 

 there are groups which resemble in many ways 

 the groups of species in other forms, since they 

 breed true to their kind, even under changed 

 conditions. They have been recognized as " smaller 

 species " by a number of botanists.* " Elementary 

 species " is the name given by de Vries, and he 

 points out that " we must recognize two sorts of 

 species. The systematic species are the practical 

 units of the systematists and florists, and all 

 friends of wild nature should do their utmost to 

 preserve them as Linnaeus has proposed them. 

 These units, however, are not really existing 

 entities ; they have as little claim to be regarded 

 as such as the genera and families have. The real 

 units are the elementary species " (p. 12). And 

 again : " Linnaeus himself knew that in some cases 

 all subdivisions of a species are of equal rank, to- 

 gether constituting the group called species. No 

 one of them outranks the others ; it is not a species 

 with varieties, but a group consisting only of 

 varieties. A closer inquiry into the cases treated 

 in this manner by the great master of systematic 

 science shows that here his varieties were exactly 



* Morgan, p. 33. 



