xii PREFACE 



service, and I have made use of this method in a number 

 of instances. For example, the transmission of the 

 effects of stimulation in nerve and other irritable forms 

 of protoplasm resembles closely certain types of chemical 

 transmission or distance-action in metal-electrolyte 

 combinations; many biocatalytic reactions are identical 

 with those induced by colloidal platinum or charcoal; 

 there are also instructive analogies between organic 

 growth and certain types of inorganic growth. Many 

 fundamental physical processes which play an important 

 part in protoplasm are independent of the special 

 chemical composition of the material; thus the influence 

 of radiation and electricity on living matter is a special 

 case of the general influence which these agents exercise 

 under appropriate conditions upon all chemical reactions. 

 The detailed nature of the conditions in protoplasm can 

 be determined only by special investigation. 



The more special sections of this book have reference 

 to the two fundamental problems above defined. The 

 structural and physico-chemical organization of living 

 matter, the modifiability of its rate of reaction under 

 varying conditions (irritability), and its transmissive 

 property (so highly developed in nervous tissues) are 

 considered in some detail; and their probable relation 

 to the pol>^hasic and film-partitioned character of the 

 protoplasmic system is indicated. 



