REGULATORY PROCESSES IN ORGANISMS 1 4S 
garded as superfluous. The further my own investigations in ~ 
this field proceed, the more completely I am convinced that those 
phenomena, which we are accustomed to call regulations are 
among the most characteristic, perhaps it is not too much to say, 
the most characteristic phenomena of life. 
The views of different authors concerning the relation between 
regulatory and ‘normal’ or ‘typical’ phenomena are very different. 
Roux (95, II, pp. 843-4), for example, makes a sharp distinction 
between typical and regulatory development, though he admits 
that the distinction is analytical rather than practical. For 
Driesch regulation is areturn approach to the normal condition, after 
this condition has been disturbed by some external factor. Many 
physiologists, on the other hand, have used the term ‘regulation’ 
in a much broader sense, as applying not only to the extra-normal 
or extra-typical but at least to many of the most typical phe- 
nomena of life. 
Because there is no general agreement concerning the real basis 
and nature of these processes, and because the regulations are of 
great importance for any interpretation of life, it seems worth 
while to undertake a brief analysis of them and particularly of the 
regulations which involve form and structure to a large extent. 
The present paper is concerned with such an analysis. 
THE ORGANISM AS A PHYSICO-CHEMICAL SYSTEM 
1. The relation between metabolism and structure 
The structural basis of living organisms consists primarily of 
colloids. These colloids, together with water, make up the greater 
portion of what we are accustomed to call protoplasm and in this 
protoplasm the various reactions and processes which character- 
ize life occur. The universal association of colloids with life 
suggests that these substances play an important part in some 
manner in determining some of the characteristic features of 
life. 
Metabolism has been commonly conceived in the past as con- 
sisting, on the one hand, of the synthesis of an exceedingly complex 
