RESPIRATION. 



339 



a determinate ratio between the pulsations 

 and repirations ; however, in many indivi- 

 duals, and I am of the number, it is as 1 to 

 4." Dr. C. Hooker* informs us that, from 

 numerous careful observations, he has arrived 

 at the conclusion, that the numerical relation 

 between the beats of the heart and the respi- 

 rations (except in infancy) is as 1 to 4|, and 

 that any marked deviation from this relation 

 indicates some mechanical or structural impe- 

 diment to the free play of the lungs. Accord- 

 ing to Burdachf, the same circumstances 

 which diminish the frequency of one of these 

 movements acts equally upon the other ; but 

 it is proved by the recent observations of Dr. 

 Ciuy, that these valuations do not bear the 

 same proportion to each other. In Dr. Guy's 

 experiments J, the proportion between the 

 respirations and the pulse has varied from 1 : 

 2*60 to 1 : 5'23 ; and whereas the pulse be- 

 comes less frequent as the day advances, the 

 respiration increases in frequency, so that 

 there are 18 respirations in the evening for 17 

 in the morning. The chief cause of the varia- 

 tion in the ratio of the respirations and the 

 pulse "is the position of the body. Thus, for 

 a pulse of 64, the proportion standing was 

 1 : 2-95 ; sitting, 1 : 3'35 ; and lying, 1 : 4*97. 

 In the sitting posture, but from different fre- 

 quencies of the pulse, it has varied from 

 1 : 2'61 to 1 : 5"00. The proportions morn- 

 ing and evening for the same frequency of the 

 pulse are about 1 : 3'60 and 1 : 3-4.0. The 

 proportions which the respiration bears to the 

 pulse decreases as the pulse increases. Thus, 

 for a pulse of 54 the proportion was 1 I 3, for 

 a pulse of 72 it was 1 : 4." 



Quantity of air drawn into the lungs at each 

 inspiration, and expelled at each expiration ; 

 and the quantity of air in the lungs at different 

 times. During ordinary respiration in a 

 state of health, and when the body is at rest, 

 a small quantity only of the air which the 

 lungs can contain is exchanged by each act 

 of inspiration and expiration. The average 

 amount of air in the lungs in the state of 

 ordinary respiration, may be considerably in- 

 creased or diminished by forced inspirations 

 and expirations, but the whole air contained 

 in the lungs cannot be expelled by the most 

 powerful action of the muscles of expiration. 

 The quantity of air drawn into the lungs by 

 each inspiration and again expelled by expira- 

 tion, in the state of ordinary respiration, not 

 only varies in different individuals, but in the 

 same individual in different conditions of the 

 body, so that the results obtained by physio- 

 logists on this point must necessarily be dis- 

 similar, and the more especially as the greater 

 number of these have experimented only upon 

 a single, or a very limited number of indivi- 

 duals. The difficulty of ascertaining the ave- 

 rage quantity of air exhaled at an ordinary 



* Boston Medical and Surgical Journal for 1838. 

 Vide also British and Foreign Medical Review, vol. 

 vii. p. 263. 



f Op. cit. p. 39. 



j Hooper's Vade-Mecum, edited by Dr. Guy, 

 pp. 131, 132. 184G. 



expiration, and the great range that occurs in 

 this respect, may be judged of by the state- 

 ment of Vierordt, that the variation in his 

 own person is as great as 1 : 4'75.* The pro-, 

 liable average quantity of air drawn into the 

 lungs at each inspiration even in healthy indi- 

 viduals, at different ages and in different states 

 of the body and of the physical conditions 

 under which it may be placed, can only be 

 ascertained by the performance of a much 

 more extended series of experiments than we 

 at present possess ; and the ascertainment of 

 the causes which determine these variations 

 from the average quantity will be still more 

 difficult, and of still more importance. All 

 such experiments are liable to many sources 

 of fallacy, both from imperfections in the 

 instruments used in conducting them, and 

 from the muscular movements of respiration 

 being unwittingly influenced by the attention 

 of the persons experimented upon being fixed 

 upon these movements ; but the later experi- 

 ments on this point are more trust-worthy 

 than the earlier, as the instruments employed 

 are better suited for the purpose, and by fre-. 

 quently repeating the experiment on the same 

 persons, they at last become accustomed to 

 the artificial circumstances under which they 

 are placed, and they breathe more naturally. 



Herbst, from his experiments, concluded, 

 that a healthy adult of average size should 

 in an ordinary inspiration inhale from 20 ta 

 25 Parisian cubic inches (24-211 to 30'263 

 English cubic inches), and exhale the same 

 quantity in expiration; while an individual of 

 a feebler constitution of body should inhale 

 from 16 to 18 Parisian cubic inches (19'368 

 to 2T789 English cubic inches). f Valentin 

 gives as the result of his experiments upon 

 seven males between 17i and 33 years of age, 

 that the quantity of air expired in ordinary up 

 to a somewhat quickened respiration, ranges 

 between 239'3 and 1567-7 cubic centimetres 

 (14-603 and 95'672 English cubic inches), 

 the average of which was 655'11 c, c. (40'081 

 English cubic inches). J Vierordt , in re- 

 peated experiments upon himself, ascertained 

 that at each expiration, when in a state of 

 rest, he expelled from the lungs on an average 

 507 cubic centimetres (30'940 English cubic 

 inches), and that the average of the five high- 

 est values was 699 c. c. (42'657 E. c. inches), 

 and of the lowest 177 c. c. (10'80l E. c. 

 inches). || Bourgery, from experiments upon 



* Wagner's Handworterbuch der Physiologic, 

 band ii. s. 836. 



f Meckel's Archiv fur Anatomic und Physio- 

 logic, band xiii. S. 83. 1828. 



J Lehrbuch der Physiologic," 1 band i. S. 538. 

 These calculations of Valentin rest on the supposition 

 that the expired air is fully saturated with moisture 

 a supposition invalidated by the experiments of 

 Moleschott. 



Wagner's Handworterbuch der Physiologic, 

 band ii. S. 835. Vierordt elsewhere states that he 

 is of the middle height, and has no particularly 

 roomy chest, was 59 kilogrammes in weight and 25 

 years of age when he performed his experiments. 



|| The following estimates have been drawn from 

 a limited number of experiments upon a single 

 individual, or upon a very small number of in- 



z 2 



