748 CHEMISTRY OF RESPIRATION. 



Temperature. 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 nmde with different methods. The 

 following are some of the results : 230 c.c., 4 656 c.c., 5 574 c.c., 6 7 

 492 c.c, 8 278 c.c., 9 328 c.c, 10 278 c.c, 11 197 c.c, 12 270 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 u 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 16 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 114196 c.c. 

 during rest, and 262-360 c.c. during exercise; in one case the tidal air 

 was as high as 1262 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. rend. 

 Acad. d. sc., Paris, 1872, tome Ixxiv. p. 190. 



2 " De Motu Animalium," p. 2, prop. 81. 



3 Phil. Trans., London, 1717-19, vol. xxx. pp. 757, 758. 



4 Goodwyn, "Connection of Life with Respiration," London, 1788, p. 28. 



5 Menzies, " On Respiration," Edinburgh, 1796, p. 18. 



6 Richerand, "Physiology," trans, by De Lys, p. 206. 



7 Fontana, Phil. Trans., London, 1779, vol. Ixix. p. 349. 



8 Dalton, Mem. Lit. and Phil. Soc. Manchester, Se*r. 2, vol. ii. p. 26. 



9 H. Davy, "Researches," p. 433. 



10 Jurine, " Encyc. 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, 1808, p. 256. 



14 Wagner's " Handworterbuch, " Bd. ii. S. 836. 



15 "Physiol. d. Athmens," Karlsruhe, 1845, S. 255. 



16 " Untersuch. ueber Sauerstoffverbrauch u. Kohlensaureausathmung des Menschen," 

 Cassel, 1871, S. 31 ; Arch. f. exper. Path. u. Pharmakol., Leipzig, Bd. xii. S. 19. 



17 Article "Thorax," Todd's "Cyclopaedia of Anatomy and Physiology," vol. iv. 

 p. 1067. 



is p roc . Physiol. Soc," Journ. Physiol., Cambridge and London, 1897, vol. xxi. 



