24 THE THEORIES OF EVOLUTION 



We can say that the revival of natural sciences 

 dates from the seventeenth century, when the micro- 

 scope was invented and the circulation of the blood 

 was accepted as a fact. The eighteenth century wit- 

 nessed a considerable advance in embryological re- 

 search as well as in the study of other special subjects; 

 records of observations on many special cases became 

 more and more numerous. The time had come when 

 that store of descriptive literature was to be put in 

 order. 



This was accomplished by Linnaeus, who through 

 his classification, systematic and practical though ar- 

 tificial, rendered science a service whose value has 

 been to this day unanimously recognised by natural- 

 ists. 



He delimited the boundaries of species, divided 

 animals and plants into classes, classes into orders, 

 orders into genera and genera into species. He gave 

 every individual two names, the first one designating 

 the genus, the other the species within the genus. 

 $uch is the origin of the binomial Latin nomenclature 

 used at present in zoology and botany. 



The idea of species assumed a considerable impor- 

 tance, and Linnaeus, influenced by the current concep- 

 tions of the time, stated his thesis as follows: "There 

 are as many different species as there were different 

 forms created in the beginning by the Supreme 

 Being." 



