94 EVOLUTION AND DOGMA. 



Definition of Species. 



We come now to the definition of the term spe- 

 cies, the critical point in the controversy between 

 creationists and evolutionists. Aristotle's concep- 

 tion of species was, as we have seen, far from being 

 precise. With his followers, for more than two thou- 

 sand years, the idea of a physiological species was 

 vague and nebulous in the extreme. It was usually 

 nothing more than a metaphysical concept, and was 

 of little or no value to the working naturalist. In- 

 deed, strange as it may seem, no definition of the 

 term species, as it is now used, was given until the 

 latter part of the seventeenth century. One of the 

 first definitions found is in the " Historia Plantarum " 

 of the noted English botanist Ray, although Yung, of 

 Hamburg, and Tournefort, the distinguished French 

 botanist, contemporaries of Ray, appear to have an- 

 ticipated the English naturalist in arriving at a true 

 conception of physiological species. According to 

 Ray, " specific characters rested not only on close 

 and constant resemblance in outward form, but also 

 on the likeness of offspring to parent, a considerable 

 measure of variability being, however, recognized." 

 Ray's definition of species and Linnaeus' binomial 

 system of nomenclature, which so greatly facilitated 

 classification, contributed immensely towards estab- 

 lishing order where chaos had so long reigned su- 

 preme. 



It would be a mistake, however, to suppose that, 

 after the labors of Ray, Linnaeus, Cuvier, and their 

 collaborators, there was perfect unanimity respect- 



