1 86 RALPH S. LILLIE. 



assigned to their proper physico-chemical classes. The similar- 

 ities between the phenomena described in this paper and many 

 of the most characteristic peculiarities of the growth-process in 

 organisms seem to me to be too detailed not to signify an identity 

 in some essential underlying condition. The need of a physico- 

 chemical analysis of the growth-process is clear; growth is un- 

 questionably the most fundamental of vital activities, and any 

 adequate theory of growth would be equivalent to a theory of 

 the vital process itself. 



