ANIMAL HEAT AND FEVER. 139 



tococcus of erysipelas) cannot live at a temperature above 41 C., 

 and cholera patients are much more likely to survive if the dis- 

 ease be accompanied by a moderate degree of fever. 



Heat stroke, or sun stroke, is due to an increase in body tem- 

 perature that is above the limits of safety. "When sweating and 

 the other processes by which heat is lost from the body are act- 

 ing properly it is remarkable how high an air temperature may 

 be borne without danger; for example, in dry air a man can sit 

 for some minutes in an oven at 100 C. while his dinner cooks 

 beside him (Leonard Hill). But if anything should interfere 

 with heat loss, or if heat production be excessive, as during mus- 

 cular exercise, there is always danger of heat stroke. Free move- 

 ment of the air is probably the most important way for safe- 

 guarding against deficient heat loss. It is almost certainly on 

 account of the absence of such air movement, coupled with a 

 high relative humidity, that discomfort is experienced in hot, 

 stuffy atmospheres, for the faulty heat loss causes a slight rise 

 in body temperature. This slight degree of hyperpyraxia low- 

 ers the resistance of the organism to infection. 



