BODY HEAT 61 



of the body is quite marked. Jurgensen, for instance, 

 found that the work involved in sawing wood for six 

 hours raises the temperature of a healthy man 1'2 C. 

 above normal. Davy showed that walking for two or 

 three hours raised the temperature of the urine 0*8 C. 

 Clifford Allbutt found that Alpine climbing raised the 

 temperature of the mouth half a degree. Hobday has 

 taken the rectal temperature of omnibus horses, and 

 found that it is raised about 2 C. by hard work.* 

 These effects, however, are quite temporary, and in 

 about a quarter of an hour after the exercise has termi- 

 nated the temperature has again fallen to normal, but 

 they will serve to show what a valuable source of heat 

 muscular metabolism is. 



When the body is exposed to cold, this source of heat 

 supply is drawn upon by throwing the muscles into 

 activity partly voluntarily (e.g., by moving about, stamp- 

 ing the feet, swinging the arms, etc.), and partly in 

 a semi- in voluntary way by the act of shivering. The 

 nerve mechanism which is made use of in throwing the 

 heat-generating apparatus into action will be described 

 immediately. 



The amount of heat which can be produced in this 

 way is very well seen in the table on page 62, which shows 

 the results which Rubner obtained from individuals 

 immersed in a cold bath. 



The bath lasted one hour. For half an hour one 

 must halve the increased heat production. 



Roughly it may be said that every fall of 1 C. in 



* These examples are taken from Hale White's Croonian Lectures 

 for 1897. 



