PHYSIOLOGICAL KEGULATIONS 441 



esses of regulation, nor of anatomical structures, except as they 

 also define the living units studied. Chemical constitutions may 

 be used to define certain components; tests and instruments to 

 define others. For each component the various latitudes, compen- 

 satory rates, and other correlatives may be listed as characteristic 

 of the organisms tested. 



(2) Regulations by equilibration may be grouped according to 

 the nature and sign of the exchanges aroused at every increment 

 of content. The feature named in each group is an element in the 

 patterns distinguished earlier (§72 and §142). Among many 

 components, one organism (dog) exhibits : 



(a) Indifference. Rate of exchange is independent of load 

 within limits; e.g., deficit of the element lead. This is a lack of 

 compensation. 



(b) Avoidance. Exchange is minimized by diminishing the 

 gain; e.g., water excess (fig. 14). 



(c) Conservation. Exchange is minimized by diminishing the 

 loss; e.g., water deficit (fig. 14). 



(d) Dissipation. Loss appears where none was present in bal- 

 ance; e.g., carbon monoxide excess (table 41). 



(e) Faster dissipation. Loss is hastened over that in balance ; 

 e.g., water excess (fig. 14). 



(f ) Accretion. Gain appears where none was present in bal- 

 ance; e.g., deficit of skin (fig. 179). 



(g) Faster accretion. Gain is hastened over that in balance; 

 e.g., water deficit (fig. 14). 



Each of these categories recognizes a direction of exchange 

 (gain or loss) and a change in rate (increase or decrease). In 

 very many loads two of these activities proceed simultaneously. 

 Where only net exchanges are known, this classification is of no 

 avail. 



An example indicating the sorts of modification concerned in 

 recoveries is heat in man (fig. 145). It was formerly supposed 

 that heat deficits are corrected by increased heat production in 

 oxidations, some or all of the increase being related to muscular 

 movements of shivering. Under many circumstances both in- 

 creased production and decreased loss are indeed realized. But 

 under the conditions of the present test no augmentation of heat 

 production is found ; net heat is solely gained by decreased rate of 

 heat loss. 



