Temperature: Metabolic Aspects and Perception 



353 



3.2 gm. of water, which absorbed 2000 cal.'--' Heat loss by conduction and 

 radiation is low, compared with loss by vaporization. Aquatic amphibia are 

 at the same temperature as the water; in air they approach wet-bulb tempera- 

 ture, heat loss by vaporization always exceeding heat production. 



Thermoreception. The skin of the frog contains receptors for both heat and 

 cold, spinal reflexes being elicited when the heat receptors are stimulated at 

 39 to 43° and the cold receptors at 10°.'-" These receptors are clearly distinct 



c 



47° - 



46< 



45 



44' 



43' 



SL 42' 



41' 



4o' 



390. 



38 



PEDICULUS HUMANUS 



LUCILIA SERICATA 



XENOPSYLLA CHEOPIS (ADULTS) 



XENOPSYLLA CHEOPIS (LARVAE) 



To 



To 



-116' 



-113° 



llo« 



lo7' 



lo4« 



-]ov 

 To% 



Relative humidity 



Fig. 88. The highest temperature at which the insects stated can survive exposures 

 of 1 hour under conditions of controlled atmospheric humidity. From Mellanby.'"' 



from touch and pressure receptors, and are probably distinct from pain recep- 

 tors, although the impulses from both thermal and pain receptors probably 

 travel in very small fibers. 



Poikilotherms in Dry Air. Insects and reptiles are poikilotherms which 

 show rudiments of temperature regulation. 



Body Temperature of Insects. Insects show wide variability with respect to 

 loss of heat by vaporization and absorption of heat by radiation. Accurate 

 temperature measurements of several large insects QBlatta and Periplaneta,^-^ 



