REGULATORY PROCESSES IN ORGANISMS 191 
mining the character of the regulatory processes. In many 
cases, however, in both plants and animals, the action of the exter- 
nal factor is so indeterminate, or the external conditions are so 
complex that equilibration may occur in various ways under what 
seem to be, but are not actually similar conditions. Thus, as 
Jennings has pointed out, in the regulation of behavior the dis- 
turbance, the stimulus, may merely bring about reactions of an 
indeterminate character, which sooner or later, in one way or 
another lead to equilibration. Evidently then the relation between 
the character of the external change and the character of the regu- 
latory process differs very widely in different cases. 
The initiating factor in regulation is the external change, the 
disturbance of the preéxisting condition. This change brings about 
changes within the organism or the part and these in turn lead to 
changes in the correlative factors, and so to equilibration or to 
disruption and death, in case the external change is such that 
equilibration of the system as a whole is impossible. But so long 
as the energetic processes of life continue in the system, equilibra- 
tion of some sort must occur. To return to the analogy of the 
river, so long as the water flows, equilibration of some sort occurs, 
whatever the changes and whatever the obstacles. The river may 
alter its course, it may transform its banks and its channel! so that 
they bear little or no resemblance to those existing before the 
change, it may divide into a number of streams, each of which 
pursues its own course, according to the conditions under which it 
finds itself, and builds up its own structural characteristics. 
In all cases, however, unless the conditions are such as to stop the 
flow of the water, equilibration takes place in some manner. 
The range of regulatory capacity in the organism represents then 
merely the range of possibilities within which the flow of the cur- 
rent of energy which constitutes metabolism and which is the 
essential feature of life, is possible. Within these limits it is abso- 
lutely inconceivable that regulation or equilibration should not 
occur. The nature of the process depends upon the nature of the 
organism and the conditions which it meets. 
Equally inconceivable is the occurrence of regulation as a 
process of life under conditions which stop the metabolic current. 
