NET AVAILABLE ENERGY—MAINTENANCE. 437 
Estimated 
Carbon dioxide | Water-vapor 
per Day, per Day, 
Grms. Grms. 
Before shearing (4 experiments). . . 719.6 1939 
After “(4 aa, Heh 725.1 434 
The total metabolism, as indicated by the excretion of carbon 
dioxide, shows scarcely any increase as a result of the shearing, and 
if we accept Pfeiffer’s suggestion that the result for the first of the 
four days (736 grams) may have been slightly affected by the stimu- 
lation of movement above noted, the difference becomes still less. 
On the other hand, the difference in the amount of water-vapor 
given off is very striking and apparently admits of but one con- 
clusion, viz., that drawn by Pfeiffer, that the unshorn animals upon 
a maintenance ration produced an excess of heat which was gotten 
rid of by evaporation of water, while the shorn animals, instead of 
meeting the greater refrigerating effect of their surroundings by an 
increased metabolism, simply evaporated less water and thus com- 
pensated for the increased loss of heat by radiation and conduction. 
Even in the case of man, where the digestive work is much 
less than in the herbivora, the heat production on a mainte- 
nance ration may be in excess, and even largely in excess, of the 
minimum requirement, it being simply a question of clothing, 
temperature, etc. This has been most strikingly demonstrated 
by Ranke,* who shows that with relatively high temperature and 
humidity the heat production on a maintenance ration may be so- 
great as to even produce pathological effects and that under such 
circumstances the consumption of food is instinctively reduced 
below the maintenance requirement. 
Sanborn,{ in experiments upon the maintenance ration of swine, 
found the amount of middlings required, per hundred pounds of live 
weight, to be as tabulated on the next page. The second summer 
experiment is not comparable with the others, since the smaller 
animal would require a relatively greater maintenance ration. 
The remaining experiments seem to show a lower requirement for 
maintenance in winter than in summer. 
* Einfluss des Tropenklimas auf die Ernéhrung des Menschen, and Zeit. 
f. Biol., 40, 288. 
+ Mo. State Agr. Coll., Bull. 28, pp. 5 and 6. 
