No. 582] SIGXIFICAXCE OF IXTFHXAL ( OX DITIOXS 



directly from the muscle as compared with arterial blood. 



The distribution of heat is accomplished by the circu- 

 lating fluids of the body, and particularly by the blood. 

 When the heat loss by radiation from the surface of the 

 body becomes too rapid, the contraction of the walls of the 

 peripheral blood vessels cuts down the quantity of blood 

 going to the surface and, hence, the loss of heat as well. 

 The constriction of the peripheral blood vessels and the 

 contraction of the muscles tend to restrict the lower limit 

 to which the body temperature may fall. The lower 

 the external temperature, the greater the supply of 

 heat from internal combustion needed to maintain the 

 usual temperature of the body unless the radiation be 

 checked by clothing or by artificial heat. It is generally 

 stated that the temperature of the unclothed human body 

 at rest may be maintained until the external temperature 

 falls to 27° C. (Senator). This statement, as will be 

 shown in a later paper, may be open to question. "When 

 the external temperature falls below this point, shivering 

 or other involuntary muscular movement begins. This 

 relation between temperature and metabolism accounts in 

 large measure for the large amounts of food sometimes 

 consumed by Eskimos. A young vigorous Eskimo may 

 eat as much as four kilograms (nine pounds) of meat in 

 a day. 22 



K. E. Ranke gives another illustration of the effect of 

 climate upon diet in Germany and in Brazil. Allowing 

 himself a free choice of food, the controlling influence 

 being his appetite, his food requirements were 3,300 to 

 3,500 calories a day, when the external temperature range 

 was from 15° C. to 22° C. In a dry atmosphere at 25° C, 

 the fuel value of the diet fell to 2,800 calories. In an at- 

 mosphere with a temperature of 25° C. to 28° C. and a hu- 

 midity of eighty-three per cent., the heat value of the diet 

 fell to 1,970 calories in a day. This diet was insufficient 



22Bi'nk, cited by Lusk, "Fundamental Knsis of Nutrition," New Haven. 

 1914, p. 28. 



