38 OLANDS IN HEALTH AND DISEASE 



its temperature is but slightly higher than that of 

 its environment, and its metabolism, therefore, 

 varies considerably from winter to summer. 



Surface area. Though for a long time the metab- 

 olism (measured in calories) of man and warm- 

 blooded animals was taken to be proportional to 

 their weight, Eubner, of the University of Berlin, 

 has shown that a closer relationship is obtained if 

 instead of the weight we substitute the surface area 

 of the man or animal that is to say, the area of 

 the surface exposed. Then we get such figures as 

 the following: 



Calories produced 



A 



Per square 



Per kilo meter of 

 surface 



Weight in kilograms 

 (1 kilo equals 2% pounds) 



Horse 441 11.3 948 



Pig 128 19.1 1078 



Man 64.3 32.8 1042 



Dog 15.2 51.5 1039 



Goose 3.5 66.7 969 



Mouse 0.018 212.0 1188 



(A calorie is the amount of heat necessary to raise one kilo of 

 water one degree centigrade. A meter is a little over a yard.) 



Making allowances for experimental difficulties 

 and inaccuracies, the last column of figures is fairly 

 constant, unlike the second, which varies consider- 

 ably. We may say then that there is an evenness of 

 heat production per unit of body surface. 



The difficulty in referring to surface area is a 



