748 CHEMISTRY OF RESPIRA TION. 
Tempered i'n\ — The frequency of respiration is greatly increased 
when the temperature of the body is raised above the normal by 
exposure to excessive heat, or by disease ; this is especially marked in 
the dog, for thereby a much greater loss of heat by evaporation of water 
from the respiratory tract is effected. Eichet has shown that this rapid 
breathing plays an essential part in the regulation of temperature in 
the dog. 1 
The volume of inspiration and expiration — Tidal air. — The 
earliest determinations of the volume of an ordinary inspiration in 
man appear to have been made by Borelli, 2 and by Jurin ; 3 the latter 
estimated the amount at 656 c.c, or 40 cubic inches. Since that time 
numerous determinations have been made with different methods. The 
following are some of the results : — 230 c.c., 4 656 c.c., 5 574 c.c., c 7 
492 c,c., s 278 c.c,, 328 c.c., 10 278 c.c., 11 197 c.c., 1 - 270 c.c. 13 
The causes of these variations are due to differences in the capacity 
of the chest of the different subjects of experiment, to individual 
differences in the breathing, and to imperfections in the methods 
employed. Vierordt 14 has collected the results of the older observers, 
and finds as the minimal capacity of a single inspiration 53 c.c, 
(Abilgaard), as the maximal 792 c.c. (Senebier). From his own 
numerous determinations Vierordt 15 obtained 446 c.c. as the mean 
volume of each inspiration, with a frequency of 11 -9 per minute, 
whereas Speck 10 with a frequency of 6 - 3 respirations per minute found 
a volume of 1195-1031 c.c. for each inspiration. 
Hutchinson 17 has collected the results of different observers, who 
found for the tidal air volumes varying from 49 to 1640 c.c. ; he himself 
made eighty determinations on different men, and obtained 114-196 c.c. 
during rest, and 262-360 c.c. during exercise ; in one case the tidal air 
was as high as 1202 c.c. 
Marcet 18 found, as the result of 210 experiments upon two men, a 
mean of 250 c.c, for the tidal air, when the rate of respiration was 
16 per minute. 
The discrepancy in the results given above is natural ; the cases are 
not comparable as regards the height, weight, age, sex, and development 
of the different subjects of experiment. It is useless, therefore, to 
attempt to give any figure which shall represent a true average, and it 
1 See " Animal Heat," this Text-book, vol. i. p. 856 ; Mathieu and Urbain, Compt. n nd. 
Acad. d. sc, Paris, 1872, tome Ixxiv. p. 190. 
2 " De Motii Animalium," p. 2, prop. 81. 
3 PhU. Trans., London, 1717-19, vol. xxx. pp. 7f>7, 758. 
4 Goodwyn, '•Connection of Life with Respiration," London, 1783, p. 28. 
5 Menzies, " On Respiration," Edinburgh, 1796, p. IS. 
I Richerand. " Physiology," trans, by De Lys, p. 206. 
'Font.ma. Phil, trans., London. 1779. vol. lxix. p. 349. 
8 Dalton, Mem. Lit. and PhU. Soc. Manchester, Ser, 2, vol. ii. p. 26. 
9 H. Davy, ''Researches,'' p. 433. 
10 Juriue, " Encye. Metropol.," art. "Medicine," vol. i. p. 494. 
11 Kite, "Essays," London, 1795, p. 47. 
12 Abernethy, "Essays," 1793, p. 142. 
13 Allen and Pepys, Phil. Trans., London, 1S0S. p. 256. 
14 Wagner's " Handwbrterbuch, " Bd. ii. S. S36. 
15 "Physiol, d. Athmens," Karlsruhe, 1S45, S. 255. 
16 " Untersuch. ueber Sauerstoffverbraueh u. Kohlensaureausathmung des Menschen," 
Cassel, 1871, S. 31 ; Arch. f. exper. Path. u. Pharmacol. Leipzig, Bd. xii. S. 19. 
"Article "Thorax." Todd's "Cyclopaedia of Anatomy and Phvsiologv," vol. iv. 
p. 1067. 
18 "Proc. Physiol. Soc," Journ. Physiol., Cambridge and London, 1S97, vol. xxi. 
