ANIMAL HEAT AND FORCE 397 



much closer if the indirect estimates are adopted. It therefore seems 

 more in accordance with ascertained facts to adopt the indirect esti- 

 mates, although this can not be done without reserve. The heat pro- 

 duced, then, is probably equal to about 2.5 heat-units (pound-degrees) 

 per hour per pound-weight of the body (nearly 1.4 kilo-degree C. per 

 kilogram). This is equal to about 8400 heat-units, or about 2120 kilo- 

 degrees C., in twenty -four hours; which is equal to about 6,500,000 

 foot-pounds, or about 900,000 kilogrammeters. 



The normal variations in the production of heat are not absolutely 

 and definitely represented by variations in the actual temperature of 

 the body and by the consumption of oxygen. Muscular work may 

 increase the production of heat sixty per cent (Him) while it increases 

 the consumption of oxygen about 4^ times, a large part of the oxidation 

 being expended in the form of work. The production of heat is dimin- 

 ished in fasting animals (dogs) by nearly forty-five per cent (Senator), 

 after deprivation of food for two days. In old age and in infancy 

 there is less heat produced than in adult life. The production of heat 

 is less in females than in males and is less during the night than during 

 the day. These points will be touched upon again, in connection with 

 the normal variations in the temperature of the body. 



Limits of Variation in the Normal Temperature in Man. One of 

 the most common methods of taking the general temperature has been 

 to introduce a registering thermometer into the axilla, reading off the 

 degrees after the mercury has become stationary. Nearly all observa- 

 tions made in this way agree with the results obtained by Gavarret, 

 who estimated that the temperature in the axilla, in a perfectly healthy 

 adult man, in a temperate climate, ranges between 97.7 and 99.5 Fahr. 

 (36.5 and 37.5 C.). Davy, from a large number of observations on 

 the temperature under the tongue, fixed the standard, in a temperate 

 climate, at 98 Fahr. (36.67 C.). The axilla and the tongue, however, 

 being more or less exposed to external influences, do not exactly repre- 

 sent the general heat of the organism; but these are the situations, 

 particularly the axilla, in which the temperature is most frequently 

 taken. As a standard for comparison, it may be assumed that the most 

 common temperature in these situations is 98 Fahr. (36.67 C.) subject 

 to variations, within the limits of health, of about 0.5 Fahr. (0.27 C.) 

 below and 1.5 Fahr. (0.82 C.) above. 



Variations with External Temperature. The general temperature 

 of the body varies, though within restricted limits, with extreme changes 

 in climate. The results obtained by Davy, in a large number of obser- 

 vations in temperate and hot climates, show an elevation in the tropics 

 of 0.5 to 3 Fahr. (0.27 to 1.65 C.). It is well known, also, that the 



