54 HISTORY OF BOTANY 



and followed by students of botany for nearly a century 

 afterwards. 



In the Philosophic* Botanica, it is true, Linnaeus does 

 express the opinion that a satisfactory classification 

 cannot be founded on pre-determined marks, but on 

 natural affinities only. It is difficult for us in these 

 post-Darwinian days to grasp precisely what Linnaeus 

 meant by natural affinities. When we think of a natural 

 classification we mean a genealogical one a phylogenetic 

 tree, in short and by implication we assume that plants 

 with similar characteristics have descended from a 

 common stock. Linnaeus held no such views. In 

 Sachs's words, " he assumed that plants of the highest and 

 lowest groups of organisation were originally created at 

 the same time and alongside of one another ; no new 

 class plants were afterwards created, but from the mingling 

 together of the existing ones by the act of the Creator, 

 generically distinct forms were produced, and the natural 

 mingling of these give birth to species while varieties 

 were mere chance variations from species." ' There 

 are just so many species," Linnaeus himself writes, " as 

 in the beginning the Infinite Being created." 



Linnaeus's chief merits, then, lie in his masterly 

 powers of analysis, description, and diagnosis, and in his 

 vigorous and effective advocacy of the binomial nomen- 

 clature, but his name is invariably and primarily associated 

 with the so-called sexual system of classification. This 

 title is quite misleading, for the system is not sexual at 

 all in the true sense of the word. Linnaeus simply 

 employed the numbers of the stamens and carpels, or, 

 more accurately, styles as a convenient means of grouping 

 plants together. It would be sheer waste of time to 

 discuss the system in detail ; you will find it set forth in 

 nearly every textbook of systematic botany that treats 

 of the historical aspect of the subject ; but I must attempt 

 in a sentence or two to indicate its fundamental features. 



Linnaeus institutes 24 classes ; the first ten of these 



