34 CUVIER 



organism, is the fundamental one at the base of all Cuvier's 

 work. Before him men had recognised more or less clearly 

 the harmony of structure and function, and had based much 

 of their work upon this unanalysed assumption. Cuvier 

 was the first naturalist to raise this thought to the level of 

 a principle peculiar to natural history. " It is on this mutual 

 dependence of the functions and the assistance which they 

 lend one to another that are founded the laws that deter- 

 mine the relations of their organs ; these laws are as inevit- 

 able as the laws of metaphysics and mathematics, for it is 

 evident that a proper harmony between organs that act one 

 upon another is a necessary condition of the existence of the 

 being to which they belong." y 



This rational principle, peculiar to natural history, Cuvier 

 calls the principle of the conditions of existence, for the 

 following reason : " Since nothing can exist that does not 

 fulfil the conditions which render its existence possible, the 

 different parts of each being must be co-ordinated in such a 

 way as to render possible the existence of the being as a 

 whole, not only in itself, but also in its relations with other 

 beings, and the analysis of these conditions often leads to 

 general laws which are as certain as those which are derived 

 from calculation or from experiment." 



By "conditions of existence" he means something quite 

 different from what is now commonly understood. The 

 idea of the external conditions of existence, the environment, 

 enters very little into his thought. He is intent on the 

 adaptations of function and organ within the living creature 

 a point of view rather neglected nowadays, but essential for 

 the understanding of living things. The very condition of 

 existence of a living thing, and part of the essential definition 

 of it, is that its parts work together for the good of the whole. 



The principle of the adaptedness of parts ma}- be 

 used as an explanatory principle, enabling the naturalist 

 to trace out in detail the interdependence of functions 

 and their organs. When you have discovered how one 

 organ is adapted to another and to the whole, you have 

 gone a certain way towards understanding it. That is 



1 Lemons d 1 Anatomic Compares, i., p. 47. 

 '-' I.e Rt^nc Animal, i., p. 6, 1817. 



