MODERN BIOLOGY 335 



boldt gives in his early work mentioned above: we observe a state that hin- 

 ders the ordinary physical and chemical forces in their efforts to dissolve 

 the body into its simple components: this is called life, and its maintenance 

 requires a constant renewal of chemical components; fresh components are 

 absorbed by the body at the same time as others already existing in it are 

 given off. Finally this process ceases, whereupon death ensues, accompanied 

 by that dissolution of the components of the body which life had prevented. 

 And this life can be produced only by previous life, but the problem of the 

 production of life is as much beyond our grasp as is that of life itself. Cuvier 

 therefore does not accept the principle of spontaneous generation. Next, he 

 gives an account of the various components of the body — their composi- 

 tion and function. His account shows that he had mastered contemporary 

 chemistry, as developed by Lavoisier and his successors; he emphasizes the 

 part played by oxygen in respiration, which is expressly compared with a 

 process of combustion; he enumerates the simple components of the body — 

 carbon, hydrogen, oxygen, and nitrogen — pointing out the importance of 

 the last-named element in the animal organism as opposed to the vegetable 

 organism. It is hardly necessary to lay stress on the vast difference between 

 this substantiated and critical exposition of life-phenomena and their basic 

 structure, and Lamarck's fantastic speculations upon life. The one predeces- 

 sor whom Cuvier most recalls in this early work of his is without doubt 

 Vicq d'Azyr. But in contrast to him there stands out at once Cuvier's origi- 

 nality, chiefly in his conception of the object of anatomy and the consequent 

 arrangement of the details of his exposition; whereas in Vicq d'Azyr the 

 function of the organs is the essential, and the basis on which the work 

 rests is therefore physiological, Cuvier thrusts the form of the organs into 

 the foreground. He holds that respiration, whose role in the renewal of sub- 

 stance is the same throughout the entire animal kingdom, is performed 

 within the separate animal classes by means of organs which are so unlike 

 one another that no comparison is possible between them. And this is also 

 the case with the organs of motion. 



His correlation theory 

 On the other hand, in similar animals there takes place a co-operation be- 

 tween the organs that makes them, as far as regards their form, entirely 

 dependent upon one another; the correlation between the separate organs 

 in the same body, which Vicq d'Azyr had already described in its main fea- 

 tures, is studied in detail by Cuvier and to him represents the very basis of 

 his conception both of animals' habits of life in nature and of their system- 

 atic classification. He points out that a carnivorous animal, while having a 

 digestive canal intended to absorb this kind of food, must also possess sharp 

 teeth for tearing the meat, jaws adapted to these teeth, claws for clutching 

 its prey, power of rapid motion, and good visual organs; a beast of prey 



