CO., 
■ °2 
= 
0-73 
)) 
>) 
)) 
) J 
068 
0-65 
0-66-0-68 
0-73-0-81 
A CTIVITY OF THE ALIMENTAR Y CANAL. 7 1 9 
fast the absorption of oxygen and the discharge of carbon dioxide were 
4 - 67 c.c. and 316 c.c. per kilo, and minute ; after this meal the 
figures were respectively 5 - 05 c.c. and 346 c.c. The effects of the fast 
and of food upon the respiratory quotient were as follows : — 
On last day of food, mixed diet 
On second day of fasting . 
On third day of fasting . 
During the remainder of the fast 
When food, mixed diet, was again taken 
Kegarding the influence of diet upon the respiratory quotient, it is 
only necessary here to state that an animal fed on a vegetable diet has a 
quotient closely approaching unity, for its chief food, the carbohydrates, 
contains enough oxygen to combine with the hydrogen to form water; 
that a carnivorous animal has a quotient about 0-74, and an omnivorous 
animal, such as man/ a somewhat higher quotient 1 ; and finally, that 
even a herbivorous animal has a low quotient during starvation, for it 
then lives upon its own tissues. 
The influence of activity of the alimentary canal upon the 
respiratory exchange. — It has already been shown that a meal 
increases the respiratory exchange, and this effect was originally attri- 
buted solely to the oxidation of the food material taken up by the 
blood. Speck,- however, in 1874, pointed out that this increase in 
metabolism followed the taking of food so rapidly that it appeared to be 
due, in the first place, to the augmented activity of the alimentary canal. 
The first experiments to support this view were those made by Mering 
and Zuntz, 3 who showed that food placed in the stomach increased the 
absorption of oxygen and the discharge of carbon dioxide, whereas sub- 
stances such as lactic acid, butyric acid, glycerin, sugar, egg albumin, and 
peptone, injected into the blood, increased the output of carbon dioxide, but 
had no marked effect upon the intake of oxygen. Rubner i and Fredericq 5 
also found increased metabolism after food, due apparently, in the first 
place, to the activity of the glands of the alimentary canal ; 6 and the 
observations made by Lehmann and Zuntz 7 upon the fasting-man 
Cetti showed that during the fast the respiratory exchange was 
constant, except on two days when Cetti suffered from colic; there 
was then an increase in the intake of oxygen and the output of carbon 
dioxide. These pieces of evidence have been followed up by Lbwy, 8 
who determined the respiratory exchange of fasting men before and 
after the activity of the alimentary canal had been increased by a dose 
of sodium sulphate, or a draught of cold water. Experiments made 
upon six men showed that the increased activity of the alimentary canal 
brought about in this way increased the intake of oxygen and the 
output of carbon dioxide by about 10 per cent, ; the greatest increase 
1 See tables on pp. 706-708. 
2 Arch./, exper. Path. u. Pliarm., Leipzig, 1874, Bel. ii. 
3 Arch.f. d. ges. Physiol., Bonn, 1877, Bd. xv. S. 634 : 1883, Bd. xxxii. S. 173. 
* Ztschr.f. Biol., Miinchen, 1883, Bd. xix. S. 330. 
5 Arch, tie biol., Gand, 1882, tome iv. p. 433. 
6 See also Slosse, Arch. f. Physiol., Leipzig, 1890, Suppl. Bd. S. 164; Tangl, ibid., 
189"4, S. 283. 
7 Perl klin. Wchnschr., 1887, S. 428. 
8 Arch. f. d. gcs. Physiol., Bonn, 1888, Bd. xliii. S. 515. 
