CALORIFIC REQUIREMENT AND THE SURFACE-LAW 587 



nuts, advocated because some of our arboreal ancestors were perforce 

 accustomed to partake of these indigestible delicacies rather freely. 



The physician, of course, will find it imperative from time to time 

 to impose quite severe restrictions upon the dietary of certain types of 

 patient, of diabetics, for example, or of persons afflicted with nephritis, 

 or with certain types of indigestion, and often he will achieve very great 

 success by this simple means. His very success, however, constitutes 

 in certain cases a positive danger to other people, through the possible 

 conversion of his patient into a dietary propagandist seeking to pro- 

 mulgate a "system" arising out of the measures which were found 

 effective in bringing about the recovery of his own health. A brief 

 but clear and simple statement by the physician of the precise object 

 of the dietary imposed, and its limited applicability, might, not infre- 

 quently, suffice to stifle a dietetic fad at its birth. 



THE CALORIFIC REQUIREMENT AND THE " SURF ACE-LAW." 



The average Starvation-metabolism of a vigorous man engaged in 

 light work and weighing 70 kilos is about 2240 calories or 32 calories 

 per kilo. To maintain calorific equilibrium this heat- value must be 

 contained in the food, and a certain excess to compensate for the 

 stimulation of metabolism or Specific Dynamic Action of foodstuffs. 

 On a normal mixed diet this amounts to from 11.1 to 14.4 per cent, 

 of the starvation-minimum (Rubner). This would indicate calorific 

 equilibrium on an intake of from 2488 to 2562 or, in round numbers, 

 2500 calories or 36 calories per kilo of body-weight. 



The total metabolism varies very greatly in different species of 

 animals, the metabolism per kilo being much higher in small animals 

 than in large. This may be inferred from the relative consumption 

 of Oxygen per hour and kilo body-weight by different species. The 

 following results are cited after Rubner: 



Grams of oxygen 



Weight, consumed per kilo 



Species. kilos. per hour. 



Calf 115. 0.481 



Sheep 66. 0.490 



Turkey , . . 6.2 0.702 



Dog 5.6 0.902 



Goose 4.6 0.677 



Rabbit 3.43 0.735 



Hen 1.51 0.846 



Duck 1.22 1.382 



Finch 0.025 13.000 



Sparrow 0.022 9.595 



The greater metabolism of the smaller animals arises, according to 

 Rubner and Richet, from the greater area of external surface in pro- 

 portion to their volume which they present. If the linear dimensions 

 of a solid are increased in the proportion of 1 : 2 the surface is increased 

 in the proportion of 1:4, but the volume in the proportion of 1:8, 

 so that the ratio of surface to volume falls to one-half. The surface of 



