LAW OF COMPENSATION 73 



organisation of mammals, there is only a single animal 

 modified by the inverse reciprocal variation of all or some of 

 its parts. Now, from the fact that there is only one 

 single general animal, it follows that for each section of its 

 components or for each of its organs there is available only 

 a given quantity of formative materials. Now suppose that 

 the distribution of these materials has not been made in 

 such a way as to ensure an exact equilibrium between all the 

 parts concerned, one organ will get more than its share, 

 another less. My law of the compensation of organs is 

 founded on these principles" (i., Lecon 16, p. 12). "The 

 atrophy of one organ turns to the profit of another ; and the 

 reason why this cannot be otherwise is simple, it is because 

 there is not an unlimited supply of the substance required for 

 each special purpose." 1 The nutritive material available 

 is limited for each species; if one part gets more than its 

 share the other parts must get less that is all the law 

 means. As an example, take the minuteness of the 

 episternals and xiphisternals in birds, as contrasted with the 

 huge size of the entosternal. " The minuteness of the 

 episternals and xiphisternals might be imputed to this 

 gigantic piece diverting to its own profit the nutritive fluid, 

 since the bigger it is the smaller these are." - 



One has constantly to remember in dealing with 

 Geoffroy's theories that he was not an evolutionist, but 

 purely a morphologist. It is therefore, perhaps, to ask too 

 much to require of him an explanation of the causes of 

 diversity. The morphologist describes, classifies, generalises ; 

 he does not seek for causes. But we must leave this 

 question aside in order to discuss how far Geoffroy's theory 

 of the unity of plan and composition fits the facts. As 

 Geoffroy himself admitted on several occasions, his theory 

 was an a priori one, a theory hit upon by hasty induction, 

 then erected into a principle and imposed upon the facts. 

 No more than Goethe did he extract his principle from a 

 sufficient mass of data. 



Now he found his theory to be in its pure form un- 

 workable ; he found, for example, that the skeleton of fishes 



1 Phil, anat., i., 450, f.n. Cf. Aristotle (supra, p. i i). 



2 Loc. cit., p. 136. 



