PIONEER INVESTIGATIONS 
to produce this effect; if prolonged so as to induce fatigue, the quantity was 
diminished. On the contrary, violent exercise seemed to lessen the quantity, 
even from the first, or if it increased the amount of carbon dioxide excreted, the 
effect was very trifling. Following violent exercise, the percentage was always 
much less. 
Table 1. — Percentages of carbon dioxide in expired air as cited by Valentin. 
Investigators. 
! 
Carbon dioxide. Investigators. Carbon dioxide. 
Valentin and Brunner . . 
M. Doyere 
p. ct. 
f 4.380 
{4.160 
14.050 
4.334 
4.400 
! Berthollet 
Fyfe 
' Jurine 
H. Davy (one isolated 
p.cL 
3.500 
5.000 
5.530 to 13.000 
6.200 to 6.500 
8.000 to 8.500 
10.000 
10.500 
H. Davy 
Prout 
Apjohn 
3.950 to 4.500 
3.300 to 4.600 
3.720 
3.600 
Since, as we now know, the percentage of carbon dioxide in the expired 
air is greatly influenced by the total ventilation of the lungs, it is obvious that 
these conclusions of Prout throw very little light upon the actual carbon- 
dioxide increment, although the fact that there was not a noticeable decrease 
in the carbon-dioxide percentage would of itself point to the fact that there 
must have been in all cases a considerably increased production — a fact that 
was many times unappreciated by the experimenters. 
Later, Valentin ° and Vierordt b showed, as did Prout, that movement 
increased the proportion of carbon dioxide contained in the gases expired. 
Vierordt was not able to make measurements of the carbon dioxide during 
work inasmuch as his method of testing required that the subject should be 
quiet; he emphasized the fact, however, that he could rely upon bis pulse 
and respiration observations during the work, and upon the carbon-dioxide 
content of the air expired after the work for solving the problems of the effect 
of activity upon the metabolism. After a brisk walk he found a great increase 
in the carbon-dioxide excretion, corresponding to 80 c.c. of carbon dioxide 
per minute. His observations on the after-effect of work are also of interest. 
He shows that this is considerable, stating: "Es ist folglich die korperliche 
Bewegung von sehr grossem und nachhaltendem Einflusse auf die Aus- 
scheidung der Kohlensaure." e 
Scharling d also studied the influence of muscular work on the carbon- 
dioxide output, the work performed being the raising and lowering of a heavy 
iron bar. A marked increase in the carbon dioxide excreted was observed. 
The influence of exercise on respiration was likewise studied by Las- 
saigne, 6 who made some very interesting observations on horses. The first 
horse exhaled per hour before exercise 341.69 grams of carbon dioxide; after 
exercising 15 minutes, he exhaled 745.90 grams of carbon dioxide. The second 
horse exhaled per hour before exercise 658.38 grams of carbon dioxide; after 
exercise, the amount of carbon dioxide exhaled was 754.88 grams. He found, 
however, that exercise had no effect on the amount of carbon dioxide excreted 
a Valentin, toe. cit. 
6 Vierordt, Physiologie des Athmens, Karlsruhe, 1845, p. 98. 
< Vierordt, toe. cit., p. 100. 
& Scharlin?, Liebig's Ann. Chem. u. Pharm., 1843, 45, p. 214. 
e Lassaigne, Joum. chim. m6dicale, 1849, 6, p. 253. 
