LINN^US AND NATURAL HISTORY 132 



being founded upon an analysis of structure, was important. 

 It was directly at variance with the idea of scale of being, and 

 overthrew that doctrine. 



Cuvier first expressed these views in a pamphlet published 

 in 1795, and later in a better-known paper read before the 

 French Academy in 181 2, but for the full development of 

 his type-theory we look to his great volume on the animal 

 kingdom published in 1 816. The central idea of his arrange- 

 ment is contained in the secondary title of his book, "The 

 Animal Kingdom Arranged According to its Organization " 

 (Le Regne Animal Distribue d'apres son Organisation, 1816). 

 The expression "arranged according to its organization" 

 embraces the feature in which this analysis of animals differs 

 from all previous attempts. 



Correlation of Parts. — An important idea, first clearly 

 expressed by Cuvier, was that of correlation of parts. The 

 view that the different parts of an animal are so correlated 

 that a change in one, brought about through changes in use, 

 involves a change in another. For illustration, the cleft hoof 

 is always associated with certain forms of teeth and with the 

 stomach of a ruminant. The sharp claws of flesh-eating 

 animals are associated with sharp, cutting teeth for tearing 

 the flesh of the victims, and with an alimentary tube adapted 

 to the digestion of a fleshy diet. Further account of Cuvier 

 is reserved for the chapter on the Rise of Comparative Anat- 

 omy, of which he was the founder. 



Von Baer. — The next notable advance affecting natural 

 history came through the work of Von Baer, who, in 1828, 

 founded the science of development of animal forms. He 

 arrived at substantially the same conclusions as Cuvier. 

 Thus the system founded upon comparative anatomy by 

 Cuvier came to have the support of Von Baers studies in 

 embryology. 



The contributions of these men proved to be a turning- 



