318 



PHYSIOLOGICAL KEGULATIONS 



of exchanges are more fully known, and extreme deficits of heat 

 have been examined. Heat regulations are acquired after birth in 

 the rabbit, neither gain nor loss being subject to effective self- 

 modification at birth. 



§ 116. Comparisons among species 



The properties of the equilibration diagram for heat in man 

 and rabbit having been established, a few quantitative diversities 

 in other species and a few general features may be mentioned. In 



Hours 



Fig. 152. Course of heat load during recovery, in various species of vertebrates. 

 Eecovery began at zero time, after heating or cooling by various means. Heat load = 

 ° C. difference from control x 0.83. Turtle, Gopherus, 2.4 kg., new data. Snake, Boa, 

 6 kg., data of Benedict ('32, p. 68). Lizard, Heloderma, (Gila monster), 1.2 kg., new 

 data. Man D, Homo, 77 kg. from figure 143. Man P, 77 kg. new data. Mouse 122, 

 0.040 kg., and Mouse 118, 0.023 kg., Mus; data of Chevillard ('35, p. 1046). Eabbit, 

 Lepus, data of Gasnier and Mayer ( '35) ; cf. figure 149. 



the actual tests an individual during loading accumulates heat or 

 cold faster or slower than usual ; thereafter initial or control con- 

 ditions are restored, allowing heat exchanges to proceed as they 

 will (fig. 152). The selection of control conditions by experi- 

 menters is arbitrary ; tests which allow the animal to select its envi- 

 ronment from among a number available (Fraenkel and Gunn, '40) 

 are to be recommended. Certainly environmental conditions 

 affect heat exchange, just as they do water exchange. Since no 



