384 PRINCIPLES OF ANIMAL NUTRITION. 
Food, Cais. | Metgbolim. | eee 
3 893 644 1.12 
Experiments on man ....... § 1855 +331 3113 
Ce ee 1250 +278 1.53 
7 2902 +1847 2.99 
AVETAZE 00... cece eeey A ere lista o arianavencbalone 2.19 
Chiefly Carbohydrates : 
2121 +1081 10.89 
Experiments on dog........ 4|]- 2226 +1094 7.19 
i 999 +8 8.91 
Average seacsceavsneeeae ck [sawiewies seme |e eae enees 8.99 
Proteids : 
: 338 —692 16.57 
Experiments on dog......... 943 —20 12.30 
1520 +461 16.05 
IAVOTORG i256 354 ARRAS ee [BHROR ORES ew SE ETRE 14.97 
Mized Diet : 
Experiments on man ......... 4193 +2171 11.76 
It is clear that proteids caused the greatest increase in the 
metabolism and fat the least, while the carbohydrates occupied an 
intermediate position. In the case of fat the increase in the heat 
production seems to show a slight tendency to become greater 
with amounts of food largely in excess of the fasting metabolism, 
but with the carbohydrates and proteids no distinct effect of this 
sort is apparent. 
These results, particularly those on proteids, afford a good illus- 
tration of the fact that the increase in the heat production caused 
by the ingestion of food is not due solely to the increased muscular 
work involved, since if we were to suppose the latter to be the case 
it is not apparent why the proteids, which are digested pretty 
promptly and with comparative ease, should cause seven times as 
much work as the fats. “The results certainly suggest strongly that 
a large part of the heat production in the former case arises from 
the considerable chemical cleavage which the proteids undergo in 
digestion and still more from the stimulative effect of food proteids 
