COMPOSITION OF THE AIR DURING RESPIRATION. 755 
a given time, net l.y ;i calculation based upon the alteration in the com- 
position of the air of several expirations, multiplied by the average 
quantity of expired air and the average number of respirations in a 
given time. 
Breathing. 
Volu 
Expired 
Air < 1 " r 
Uinute). 
ntage 
ol ( txygen 
in Expired 
Air. 
Quantity 
of Oxygen 
Absorbed 
(per 
Minute). 
Percent- 
Carbon 
Dioxide in 
Expired 
Air. 
1 it y 
ol < larbon 
Dioxide Dis- Observer. 
charged (per 
.Minute). 
Normal 
Very shallow 
Very deep . 
Normal. J, 
Work 
Hard work . 
Normal 
Normal 
c.c. 
7,527 
5,833 
17. ''.47 
>;.ir.> 
16,191 
24,323 
1,644 
3,419 
16-29 
15-50 
18-29 
17-00 
17-29 
16-96 
16-16 
16-96 
C.C. 
358 
330 
437 
240 
587 
964 
222-9 
136-8 
4-21 
4-63 
3-17 
3-56 
3-65 
4-08 
4-36 
3-44 
C.C. 
318 ) 
269 Speck. 1 
560 1 
218 1 
593 -Speck. 2 
993 1 
202-7 \ T - 3 
ii7-6 j L,,w r- 
Vierordt 4 concluded from his experiments that the percentage of 
carbon dioxide in the expired air diminished, but the total discharge 
increased when the respiration was voluntarily quickened, the depth of 
breathing remaining the same, 500 c.c. ; similar effects were produced by 
breathing more deeply but with the same frequency. The drawback to 
these observations is that they were for periods only lasting two or 
three minutes, and thus they are no exact measure of changes of meta- 
bolism. Even the extended observations of Lossen and Berg have been 
the subject of much discussion and criticism between Ptiiiger 5 and 
Voit. 6 It is impossible here to go fully into the causes of some of the 
contradictory results, but Ptiiiger appears to have shown that the 
variations in the breathing have no influence upon the respiratory 
metabolism beyond this, that when the respiratory muscles are more 
active, an extra amount of metabolism, due to this activity, will occur. 
Pfliiger takes the mean of the conflicting results and obtains the 
following suggestive figures : — 
Carbon dioxide discharged in fifteen minutes — 
Authority. 
Five Respirations 
per Minute. 
Sixty Respirations 
per Minute. 
Lossen . 
Berg . 
7 "96 grms. 
7-712 ,, 
15-672 ,, 
Mean . 7 "836 ,, 
6-63 grms. 
9-106 ,, 
15-736 ,, 
Mean . 7'S68 ,, 
1 Arch. d. Ver.f. wissenseh. Hdlk., Leipzig, 1S67, Bd. iii. S. 317. 
2 " Physiologie des menschlichen Athmens," Leipzig, 1892 ; Arch. f. Physiol., Leipzig, 
1896, S. 465. 
3 Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xliii. S. 523, et scq. 
* Hesse, Arch. f. Hyg., fttiinchen u. Leipzig, 1884, Bd. ii. S. 381; "Physiol, d. 
Athmens." Karlsruhe, 1845, S. 116, 134. 
5 Arch. f. d. ges. Physiol., Bonn, 1S77, Bd. xiv. S. 1, 630. 
6 Ztschr. f. Biol., Munchen, 1S78, Bd. xiv. S. 95. 
