REGULATORY PROCESSES IN ORGANISMS 203 
example the part a dominates the other parts, or if the change 
in a is so great that the correlative factors resulting from it 
become dominant, then an increment in a may bring about an 
incremental compensation, a decrement in a a decremental com- 
pensation. On the other hand, if the parts b, c, d—n, or certain of 
them, dominate a, then they may inhibit or reverse the incremen- 
tal or decremental change in a and reversional compensation 
results. And finally, alterative compensations occur whenever 
changes in one part induce correlatively changes in the opposite 
direction in others. 
An incremental compensation occurs when increased metabo- 
lism and growth follow the ingestion of food, a decremental com- 
pensation, when decreased activity of a sense organ or a muscle 
induces a correlative decrease in activity and perhaps atrophy in 
parts with which it is connected, e. g., the center in the case of the 
sense organ, the tendon, or even the bone in the case of a muscle. 
In various temperature regulations in warm-blooded animals we 
have reversional compensations, and finally, in many cases of 
regeneration and probably also often in normal development, al- 
terative compensations occur, e. g., when increased growth of one 
part retards correlatively the growth of another or perhaps induces 
reduction in it. — 
The chemical substances which arise in the course of metabo- 
lism in certain parts very often produce compensations of various 
kinds in other parts. A good example is the correlative effect of 
increase in the carbon dioxide in the blood through the nervous 
system upon the rate of respiration. The recent work of Bayliss 
and Starling and others on ‘hormones’ gives us some insight into 
various other cases of compensation and other regulatory reactions ; 
the distribution of nutritive substances in the starving animal and 
under various other conditions also constitutes compensations of 
various kinds; the correlative changes in so-called functional 
structure are in many cases very characteristic compensations. 
Incidentally it may, be pointed out that the view of the relation 
between metabolism and structure suggested above affords a 
basis for interpretation to a certain extent of the processes of 
functional hypertrophy and atrophy from disuse. 
JOURNAL OF MORPHOLOGY, VOL. 22, NO. 2 
