76 Trans. Acad. Sci. of St. Louis. 



binomial system this was entirely obviated. The first name, 

 usually a noun, denotes the genus; the second, usually an 

 adjective, the species. Thus, Canis familtaria, Canis lupus 

 and Canis vulpes indicate the dog, the wolf and the fox 

 respectively, and moreover, that they all belong to a common 

 genus of dog-like animals, though representing different 

 species within the genus. He further grouped his genera 

 into orders and the orders into classes, and into these four 

 divisions, classes, orders, genera and species he arranged the 

 entire animal kingdom, like the subdivisions of an army, 

 the greater group containing several of the lesser. Although 

 Linnaeus treated of a far larger number of animals than 

 any of his predecessors, nevertheless, his classification as 

 a whole was a retrogression from Aristotle's. He divided 

 animals into six classes ; namely. Mammalia, Aves, Amphibia, 

 Pisces, Insecta and Vermes. The first four correspond to 

 Aristotle's haqxa^ or blood-containing animals, the Insecta and 

 Vermes to the avai[ia^ or bloodless animals ; but among the 

 latter he does not recognize as many distinct groups as did 

 Aristotle, and hence, we may regard the classification as a 

 backward step. 



Linnaeus adopted Ray's conception of species, regarding it 

 as a fixed, permanent, objective reality, and maintaining that 

 species were created as such in the beginning by the Infinite 

 Being, and that just as many species are present as have been 

 from the first. This erroneous conception of species was 

 destined to last for over a century, and only disappeared 

 finally when the acceptance of the descent-theory became 

 general. 



Great as was the service rendered by Linnaeus' reform in 

 classification, it nevertheless contained the germ of a one- 

 sided development, for there soon arose a great array of 

 systematists who, in their zeal and enthusiasm for naming 

 and classifying animals and plants, made this the end and 

 aim of the study of zoology, and failed to appreciate the ob- 

 vious truth that the work of classification is merely an aid to 

 the investigation of the fundamental problems and not a goal 

 in itself. The ultimate purpose of the science, namely, the 

 investigation of the nature and causes of living things, was 



