Chapter XIV 

 HEAT 



'^ 111. Introduction 



The investigation pursued thus far has presented, both in detail 

 and in general, the physiological relations of water and of certain 

 volumes. The relations are such as are known to be implicated in 

 the maintenances of water content and exchanges in living units. 

 The patterns found might be peculiar to water, or else some 

 features might be common to many components. To find which, 

 it is necessary to study other physiological components, and in con- 

 siderable variety. To this end, the term component is not limited 

 to chemical entities, but is extended to include all sorts of quantita- 

 tive properties of living units. Perhaps anything that can be 

 measured in the organism may be treated in a fashion analogous 

 to that in which water and volume were treated. That too can be 

 ascertained only by trying. 



The investigation now becomes an inquiry into maintenance and 

 recovery of various functions of organisms, and ultimately of the 

 interrelations among maintenances. The components chosen for 

 intensive study (chapter XV) may or may not turn out to be a ran- 

 dom sample of the very large number that can ultimately be stud- 

 ied. Even though future physiology may discover types of regu- 

 lation not yet observed, the relations described herewith prevail in 

 the situations named. 



Certain choices could be exercised among the data available. 

 All the components might be selected for one species (dog), or for 

 one type of production of increments (exercise by running), or for 

 one path of exchange (urinary). Instead I propose to utilize data 

 that seem to me most adequate, distributed quite at random in 

 these and other respects. In the end the study yields a partial 

 picture of a block of physiological patterns that operate together 

 in one individual. 



Heat is the first component to be considered, and the species 

 chiefly studied are man and rabbit. How are heat exchanges and 

 other properties modified when a man is warmer or cooler than 

 usual? What is usual? 



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