372 PRINCIPLES OF ANIMAL NUTRITION. 
ments, on the contrary, since the heat production decreased along 
with the decrease of nitrogenous tissue, we see the regulation of 
body temperature effected by a diminution in the rate of emission 
of heat, which, however, was in most cases less marked than in the 
instance just cited. Either we must conclude that the abnormal 
condition arising from fasting enables the animal to diminish the 
rate of emission of heat to an extent not possible to the well- 
nourished one, or we may suppose that in the latter case the stimu- 
lation of the metabolism by the abstraction of heat begins before 
the possibilities of “physical” regulation have been exhausted; 
that, in other words, the domains of “chemical” and “ physical” 
regulation overlap. Obviously the latter conclusion is entirely in 
harmony with v. Hésslin’s views as stated on pp. 367-8. 
§ 3. The Expenditure of Energy in Digestion and Assimilation. 
General Conception. 
Foop Increases Metasoiism.—That the consumption of food 
increases the metabolism and consequent heat production in the 
body has been known since the time of Lavoisier, who observed 
the oxygen consumption of man to increase materially (about 37 
per cent.) after a meal. Regnault & Reiset * also, among their 
respiration experiments on animals, report the following results 
for the oxygen consumption of two rabbits while fasting and after 
eating: 
ee 
DN oss gs dite Ses 2.518 3.124 
Bag exe negaes 2.731 3.590 
Subsequent investigations by Vierodt, Smith, Speck, Fredericq, 
v. Mehring & Zuntz, Wolfers, Potthast, Hanriot & Richet,t Magnus- 
Levy, Zuntz & Hagemann, Laulanié, and others, some of which will 
be considered more specifically in subsequent paragraphs, have fully 
confirmed these earlier results, so that the fact of an increased met- 
abolism consequent upon the ingestion of food is undisputed. 
* Ann, de Chim. et de Phys. (3), 26, 414. 
t Ibid, (6), 22, 520. 
