340 



RESPIRATION. 



fifty males and twenty females*, with the view 

 of ascertaining the relation between the inti- 

 mate anatomical structure of the lungs, and 

 the functional capacity of these organs in the 

 two sexes, concludes that the volume of air 

 required by an individual in ordinary respira- 

 tion augments gradually with the age, being 

 least in youth (from 5 to 15 years), in conse- 

 quence of the extreme vascularity of the 

 lungs ; increased from 15 to 30 years of age, in 

 consequence of the proportional diminution 

 in the closeness of the pulmonary capillary 

 network of blood vessels ; and to a much 

 greater amount in old age, in consequence of 

 the more rapid diminution of the extent of 

 the respiratory membrane, which begins to 

 take place after the lungs have arrived at their 

 full development, or the age of 30. 



It is obvious that we are not yet in posses- 

 sion of data to enable us to venture upon an 

 estimate of the average quantity of air in- 

 spired and expired at an ordinary respiration, 

 when the body is at rest and the mind undis- 

 turbed, at different periods of life, in the two 

 sexes, and in different physical configurations 

 of body. It is equally apparent that this 

 is liable to considerable variation, and that 

 the different results obtained by most experi- 

 menters, setting aside those where an obvi- 

 ously faulty method was pursued, depends 

 as much upon the inherent differences in 

 the extent of the respiratory movements in 

 the individuals experimented upon, as upon 

 errors in the mode of experimenting, and that 

 the chief error committed by some of them 

 consists in deducing averages from the few 

 and insufficient experiments performed by 

 themselves, and casting doubts upon the 

 results obtained by others, simply because 



dividuals, and are therefore of little value in enabling 

 us to ascertain the average quantity of air taken into 

 the lungs and again expelled in ordinary respiration. 

 Besides, some of these experiments are liable to 

 obvious objections. Borelli (De Motu Animaliuin, 

 Pars Secuuda, p. 118. Lugdani, 1685) who appears 

 to have been the first who attempted to ascertain 

 this by experiment, estimates it at 1.5 cubic inches. 

 Turin (Diss. p. 41, 42, as quoted by Haller), from 

 experiments on his own person, at 40 cubic inches ; 

 and this is the estimate also formed by Menzies 

 (op. cit. p. 28,) from his experiments. Goodwyn (The 

 Connexion of Life with Respiration, &c., p. 36. 

 1788), from experiments on three individuals, esti- 

 mates the quantity inspired at 12 cubic inches, which 

 he supposes to be increased to 14 in the lungs by the 

 increase of temperature. Sir H. Davy (Researches 

 Chemical and Philosophical, &c., pi 433, 1800) 

 informs us that he threw out of his lungs at each 

 ordinary inspiration nearly 13 cubic inches; Mr, 

 Abernethy (Surgical and Physiological Essays, Part 

 II. p. 142, 1793), that he inspired 12 cubic inches; 

 Dalton (Memoirs of the Literary and Philosophi- 

 cal Society of Manchester, 2nd Series, vol. ii. p. 26), 

 also from experiments on his own person, esti- 

 mates an ordinary inspiration at 30 cubic inches ; 

 Allen and Pepys (London Phil. Trans, for 1808), 

 from experiments on one individual, at IGg cubic 

 inches; and Thomson (Animal Chemistry, p. 612. 

 1843) estimates his own inspirations at' 16 cubic 

 inches. 



* Arehiv. General, de Med. 4 e Serie, torn. i. p. 

 875, 1843, and Comptes Reudus, 23 Janvier, p. 182. 

 1843, 



they do not accord with their own. It also 

 necessarily follows that we are not in a posi- 

 tion to form an estimate of the average quan- 

 tity of air which passes out and in from the 

 lungs in twenty-four hours in ordinary respi- 

 ration. Vierordt*, from experiments on his 

 own person, calculates that he respires 6034 

 cub. cent. (368'074 English c. inches) of 

 atmospheric air in one minute, or 8,688,960 

 cub. cent. (530,026-560 Eng. c. in.) in the 

 twenty-four hours. As, however, the respi- 

 ration is rendered more energetic by speaking, 

 walking, &c., any estimate drawn, as this by 

 Vierordt is, from observations made when 

 the body was in a state of rest, will be, as he 

 was aware, too low ; and proceeding on some 

 of the results of Scharling's experiments, he 

 makes allowances for this increase, and esti- 

 mates the quantity of air respired in the 

 twenty-four hours at 624,087'401 English 

 cubic inches. Valentin -j* calculates that in 

 his own person, after making allowances for 

 temperature and watery vapour, he respires 

 469-9755 litres (28681 1948 English cubic 

 inches) in an hour, and 688,348-676 1 Eng. 

 cubic inches, or nearly 398.1 cubic feet of 

 atmospheric air in the twenty-four hours. J 



The quantity of air drawn into the lungs 

 during quickened or forced inspiration, and 

 again expelled during expiration, also varies 

 very considerably in different individuals of 

 the same age. Sir H. Davy, in many ex- 

 periments upon himself, ascertained that at a 

 temperature from 58 to 62 Fahr. he threw 

 out of his lungs by a full forced expiration, 



Cubic Inches. 



After a full voluntary inspiration, 



from 189 to 191 



After a natural inspiration, from 78 79 

 After a natural expiration, from 67 68 



So that, making corrections for temperature, 

 he calculates that his lungs, in a state of vo- 

 luntary or forced inspiration, contained about 

 254 cubic inches ; in a state of natural in- 



* Op. cit, pp. 856, 857. 



f Op. cit. p. 570. The effects of exercise, diges- 

 tion, &c., are included in this estimate. 



J Mr. Coathupe (London and Edinburgh Phil. 

 Magaz. vol. xiv. p. 401, 1839), from experiments 

 on his own person in a state of rest, estimates the 

 number of respirations at 20 in the minute, the 

 average bulk of each respiration at 16 cubic inches, 

 and the quantity of air that passes through the 

 lungs in 24 hours, at 460,800 cubic inches, or 266-66 

 cubic feet. Mr. Coathupe's estimate agrees pretty 

 closely with that of Dumas (Statique Chimique des 

 Etres" Organised, 3 e edit. p. 87), also formed from 

 experiments on his own person, in a state of rest. 



The estimate of the quantity of air that passes 

 through the lungs, given by Bostock (System of 

 Physiology, p. 321, 1836) is in all probability above 

 the average. He proceeds on the supposition that 

 in ordinary respiration a man respires 40 cubic 

 inches of air 20 times in a minute, so that he makes 

 the quantity respired in the 24 hours, 1,152,000 cubic 

 inches or about 666 cubic feet, It is probable that 

 between 25 and 30 cubic inches of air for each ordi- 

 nary inspiration will be found to be near the average 

 in an adult male when in a state of rest. 



Researches Chemical and Philosophical, &c., 

 p. 410. 1800. 



