CELLULAR ORGANIZATION OF LIVING MATTER 19 



structure determines, in a quite special way, the character 

 of the protoplasmic processes; i.e., has its own definite 

 causative and controlling influence. The metabolic and 

 other cell processes can be shown to be profoundly 

 influenced by changes in the physical and other state 

 of cell structures. For example, there is evidence that 

 in most cells irritability depends primarily upon the 

 special properties of the external protoplasmic layer 

 or plasma membrane; the contractile, secretory, and 

 similar mechanisms are cell structures; the special 

 relation of the nucleus to constructive metabolism 

 has already been mentioned. In general we may say 

 that physiological activity in all higher organisms is 

 intimately bound up with the special features of 

 structure, chemical organization, and activity peculiar 

 to cells. 



A universal peculiarity of living matter, considered 

 simply as a chemical reaction- system, is that its principal 

 chemical reactions, especially the specific constructive 

 group, occur under the control of structural conditions. 

 If protoplasmic structure is destroyed, mechanically or 

 otherwise, these essential vital reactions at once cease. 

 New structure as it arises in growth or development 

 must therefore have a modifying influence on the meta- 

 bolic processes and the other physiological processes 

 dependent upon these. The structural characters pecu- 

 liar to cells cannot fail to influence profoundly the 

 chemical activity of all living systems having the cellular 

 type of organization. One of the fundamental problems 

 of general physiology has reference to the special nature 

 of the relations existing between cellular structure and 

 the chemical processes of the cell protoplasm. 



