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, 

 and inquiries into the nature of fermentation 

 and the role of microorganisms are examples 

 of the older tendencies. Such interests have, 

 it 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 

 point 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, 

 plus ou moins complique, dont la direction est constante, 

 et qui entrafne toujours des molecules de memes sortes, mais 

 ou les molecules individuelles entrent et d'ou elles sortent 

 continuellement, de maniere que la forme du corps vivant 

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

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

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

 ties sont dans un tourbillon continue!, qui est une condition 

 essentielle du phenomene, et que nous ne pouvons suspendre 

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

 simples de l'histoire naturclle participent deja a cette compli- 



