REGULATORY PROCESSES IN ORGANISMS 207 
Very probably various ‘sports’ and mutations can be placed under 
this head, perhaps also certain of the neoplasms, more specific- 
ally the malignant tumors, though this is by no means certain. 
But whatever the categories which we may establish for the dif- 
ferent regulatory processes, the important point is that we should 
at least make the attempt to find a physico-chemical basis for our 
analysis. If we do this we cannot separate structure and function 
since both are merely different aspects of the same process-com- 
plex and are dependent upon and determine each other. Doubt- 
less we shall still find it convenient to speak of form regulation as 
distinguished from functional regulation, but we must remember 
that the distinction is not a real one and that every regulation in 
the organism is undoubtedly a regulation of both form and func- 
tion, of both structure and reactions. Furthermore, we must 
regard our experiments on regulation as means of analyzing the 
factors of the process. With the proper care in experiment we can 
do much toward determining the nature and action of various 
correlative factors in regulation, and every step in this direction is 
a step in advance in our knowledge of the system which constitutes 
the organism. 
THE NATURE OF RECONSTITUTION * 
1. Restitution or reconstitution ? 
When an organism ‘restores’ a missing part or in general when a 
part of an organism forms a whole, the process seems at first 
glance to be so obviously a restoration in which something re- 
moved is replaced, that the term ‘restitution’ has found very 
general favor. Although I have used this term to a large extent, 
it has always seemed inadequate, for the reason that the proc- 
ess is not simply one of restoration but something more. There 
is no case of so-called restitution known in which the changes 
following the removal of a part are limited to the formation of a 
new similar part. In every case changes of one kind or another, 
quantitative or qualitative, or both, occur in other parts, some- 
times limited chiefly to parts adjoining the part removed, some- 
times extending throughout the system. The removal of a part 
