238 FROM THE GREEKS TO DARWIN 



factors and nature of the evolution of life, which 

 he first expressed in the Philosophie Zoologique 

 of 1809 and fully formulated later in the His- 

 toire Naturelle (1815-22) into the four well- 

 known propositions: 



Premiere loi. — La vie, par ses propres forces, 

 tend continuellement a accroitre le volume de 

 tout corps qui la possede, et a etendre les dimen- 

 sions de ses parties, jusqu'a un terme qu'elle 

 amene elle-meme. (Life by its own forces tends 

 continually to increase the volume of every body 

 that possesses it, as well as to increase the size of 

 all the parts of the body up to a limit which it 

 brings about. ) 



JDeuxieme loi, — La production d'un nouvel 

 organe dans un corps animal, resulte d'un nou- 

 veau besoin survenu qui continue de se faire sen- 

 tir, et d'un nouveau mouvement que ce besoin 

 fait naitre et entretient. (The production of a 

 new organ or part results from a new need or 

 want, which continues to be felt, and from the 

 new movement which this need initiates and 

 causes to continue. [This is the psychical factor 

 in his theory, which Cope later termed Archses- 

 thetism.]) 



Troisieme loi. — Le developpement des organes 

 et leur force d 'action sont constamment en raison 

 de I'emploi de ces organes. (The development of 

 organs and their force or power of action are 



