BODY HEAT 69 



fever, for in that case the rise of temperature of the body 

 would be steady and progressive. It is probable, how- 

 ever, that diminished loss plays a large part in the 

 production of liyperpyrexia in which the rise of tempera- 

 ture is marked by those very characters. We may 

 conclude, then, on physiological grounds alone, apart 

 from the evidence of pathology, that in most cases fever 

 is due to a disturbance of the normal balance between 

 manufacture and loss of heat, or, in other words, to 

 a disorder of the internal heat-regulating mechanism. 

 What the nature of this disorder may be is uncertain, but 

 it has been suggested that the poisons which produce 

 fever lower the sensitiveness of the internal heat-regulat- 

 ing mechanism, so that (to compare it with a thermo- 

 stat) it is ' set ' for a higher temperature than in health. 

 It is further of importance, in considering fever, to 

 distinguish between the mere temperature of the body 

 and the total amount of heat which it contains. The 

 'specific heat ' of the human body is high; i.e., it takes 

 a considerable amount of heat to raise its temperature, 

 and the larger the mass of the body, the greater is the 

 amount of heat required. Other things being equal, 

 therefore, a given rise of temperature signifies a greater 

 amount of heat production in a large body than in a 

 small one. There is also every reason to believe that 

 the specific heat of the body rises with an increase of its 

 temperature, or, in other words, the hotter the body 

 becomes, the greater is the amount of heat required 

 to heat it still more. It follows from this that a rise of 

 temperature from 104 to 105 F. is of relatively graver 

 significance than a rise from 99 to 100 F. 



