HOW HEAT IS LOST 141 



The production of heat (thermogenesis) is lessened in 



various ways : The use of cold water, chiefly in the form 

 of cold bath or cold packing, diminishes abnormal thermo- 

 genesis. Water absorbs and parts with heat quickly ; it 

 is capable of application locally or generally, continuously 

 or intermittently. Cold water taken into the system, by 

 whatever channel, increases the activity of healthy vital 

 processes, notably metabolism, elimination, and leucocy- 

 tosis, and thus both lessens abnormal heat formation and 

 increases heat loss. 



Quinine and its allies lessen metabolism in the tissues, 

 prevent the oxidation of protoplasm, and the movement of 

 leucocytes, and so prevent the formation of heat. Thus 

 experiments show that these agents will still lower tempera- 

 ture if loss of heat by radiation from the skin is prevented 

 by clothing and rugs. Alcohol probably acts to some extent 

 in the same way. 



Aconite also, and other agents which depress the circula- 

 tion, lower abnormal temperature by preventing the forma- 

 tion of heat. 



The loss of heat (thermolysis) is increased, as set forth in 

 the above table, chiefly in the following ways : 



(1) By the antipyretics of the coal tar series of hydro- 

 carbons. These agents are experimentally found to act on 

 the thermotaxic or heat-regulating centre in the brain. In 

 health heat formation and heat loss balance one another in 

 such a way that the normal temperature of the animal is 

 preserved, and these drugs have little or no reducing effect 

 on this normal temperature. In fever the regulating centre 

 is still acting, but now its mean point has been raised to an 

 abnormal level. Thus exertion causes a fevered animal to 

 sweat and lose heat, but this does not result in lowering of 

 the temperature, for metabolism and heat formation go on to 

 an extent sufficient to keep up the temperature to its former 

 abnormal level. In other words, the centre now aims at 

 keeping the temperature at the suitable temperature for the 

 particular disease, and appears to have been geared up to 

 work at that level. The antipyretics such as phenazone 

 (antipyrine), and acetanilide (antifebrin), act on the centre 

 and bring it down again to its normal level. As a conse- 



