FITNESS 23 



Until very recent times, however, the 

 main interest has centered upon morpho- 

 logical problems and upon the processes of 

 growth and development. The ancient con- 

 troversies regarding types and homologous 

 parts, the question of spontaneous genera- 

 tion and the whole science of embryology, 

 an J inquiries into the nature of fermentation 

 and i he role of microorganisms are examples 

 of the older tendencies. Such interests have, 

 , need hardly be said, lost none of their im- 

 portance, but they scarcely touch the physico- 

 chemical problem of the nature of living 

 things. Yet there is in these subjects one 

 pom! of view, a favorite of Cuvier's, now, 

 though still familiar, less often emphasized, 

 which states a most important characteristic 

 of life in terms of matter and energy, space 

 and time. 1 Living things preserve, or tend 



1 ' La vie est done un tourbillon plus ou moins rapide, 



i ou moins complique, dont la direction est constante, 



.i entraine toujours des molecules de memes sortes, mais 



ou les molecules individuelles entrent et d'ou elles sortent 



Linuellement, de maniere que la forme du corps vivant 



lui est plus essentielle que la matiere." ("Regne animal," 



13, etc.) "II vient sans cesse des elements du dehors en 



,ns : il s'en echappe du dedans en dehors : toutes les par- 



-■ont dans un tourbillon continuel, qui est une condition 



W tielle du phenomene, et que nous ne pouvons suspendre 



longtemps sans l'arreter pour jamais. Les branches les plus 



pies de l'histoire naturelle participent deja a cette compli- 



