240 THE ORIGIN AND EVOLUTION OF LIFE 



some of the hypotheses regarding animal structure and evolu- 

 tion which have been entertained since the first analyses of 

 animal form were made by Cuvier at the beginning of the last 

 century. The independent adaptation of each character group 

 to its own particular function proves that there is no such essen- 

 tial correlation between the structure of the teeth and the struc- 

 ture of the feet as Cuvier claimed in what was perhaps his 

 most famous generalization, namely, his "Law of Correlation."^ 



Again this principle, of twofold, threefold, or manifold adap- 

 tation, is fatal to any form of belief in an internal perfecting 

 tendency which may drive animal evolution in any particular 

 direction or directions. Finally, it is fatal to Darwin's original 

 natural-selection hypothesis, which would imply that the teeth, 

 limbs, and feet are varying fortuitously rather than evolving 

 under certain definite although still unknown laws. 



The adaptations which arise in the search of many varieties 

 of food and in overcoming the mechanical problems of loco- 

 motion, offense, and defense in the twelve different habitat 

 zones are not fortuitous. On the contrary, observations on 

 successive members of families of mammals in process either 

 of direct, of reversed, or of alternate adaptation admit of but 

 one interpretation, namely, that the evolution of characters is 

 in definite directions toward adaptive ends; nor is this definite 

 direction limited by the ancestral constitution of the heredity- 

 chromatin as conceived in the logical mind of Huxley. The 

 passage in which Huxley expressed this conception is as follows : 



"The importance of natural selection will not be impaired 

 even if further inquiries should prove that variability is definite, 

 and is determined in certain directions rather than in others, by 



1 Cuvier's law of correlation has been restated by Osborn. There is a fundamental 

 correlation, coordination, and cooperation of all parts of the organism, but not of the 

 kind conceived by Cuvier, who was at heart a special creationist. Contrary to Cuvier's 

 claim, it is impossible to predict from the structure of the teeth what the structure of 

 the feet may prove to be. 



