HEAT 319 



method is possible of doing away with the environment, the organ- 

 ism's provisions for dealing with heat loads are, I believe, mani- 

 fested most clearly when the environment is uniform throughout 

 one series of tests. In a more extensive inquiry, many quantita- 

 tive relations would be established for one organism recovering in 

 each of many environments. In daily life the organism is continu- 

 ally shifting its rates of heat exchange to cope with complicating 

 circumstances as they ari^e. 



Most organisms (poikilothermic) attain temperatures approxi- 

 mating those of the environment or parallel to them, and often they 

 show curves of cooling or warming partially similar to those of 

 inanimate objects (fig. 152). In others (homeothermic) the net 

 exchanges are sometimes opposite in direction to that toward cus- 

 tomary inorganic equilibrium. In poikilothermic species rates of 

 heat exchanges are still of consequence in maintaining a gradient 

 of heat. 



Terroine and Trautmann ('27) ascertained the relations be- 

 tween rates of heat production and air temperatures in each of 12 

 homeothermic species. Each showed a minimal rate at some inter- 

 mediate (''neutral") temperature. The rates could now be re- 

 lated to heat loads if data upon mean body temperatures had also 

 been obtained. Each of those 12 species has its own relation be- 

 tween augmentation of heat production and increment of tempera- 

 ture, some species being more responsive than others to equal heat 

 increments. That might be a basis for visualizing a phylogenetic 

 gradation of regulations. 



Maximal rates of heat production in heat loads divided by 

 minimal rates are ratios of modification. Under the name of 

 "metabolisme du sommet," they were found by Giaja ('25a) to be 

 3.2 to 4.2 in the mouse and four other species, but by Herrington 

 ( '40) only about 2.2. Even in monotremes, in which the heat con- 

 tents are irregular, augmentations of that order are found in low 

 air temperatures (Martin, '02). It may be said that the mono- 

 tremes' inexact maintenances of body temperature are not the out- 

 come of mere inability to modify their heat productions. 



Portions of further equilibration diagrams might be established 

 for other species, particularly the dog (Wada et al., '35 ; Heming- 

 way, '38; Shelley and Hemingway, '40) and the mouse. The latter 

 species recovers from temperature deficits more rapidly than 

 larger mammals (fig. 152). During recovery, heat is produced by 



