336 



RESPIRATION. 



the lower part, and women by the upper part 

 of their chest, and this independently of the 

 effects of particular articles of dress ! * This 

 difference in the mode of respiration in the 

 two sexes is, in general, maintained even in 

 dyspnoea, unless it be very severe. As the 

 costo-inferior and abdominal types of respi- 

 ration would be impeded in the female when 

 pregnant, the ordinary costo-superior type of 

 respiration in the female has apparently a 

 reference to that condition.-}- 



Valentin , Dr. Hutchinson$, and Men- 

 delssohn ||, have lately made experiments upon 

 the force of the muscular movements of in- 

 spiration and expiration. Those of Dr. Hutch- 

 inson are much the most extensive, and are 

 1500 in number. He found that the power 

 of expiration is nearly one third stronger 

 than that of inspiration ; and he states that 

 whenever the expiratory are not stronger 

 than the inspiratory muscles, that some dis- 

 ease is present. He tested the force of the 

 two classes of respiratory muscles b} 7 causing 

 persons to make the most powerful efforts of 

 which they were capable when breathing 

 through the nose into an instrument con- 

 structed for the purpose, and the subjects of 

 experiment were taken from individuals of 

 the male sex, following very different occu- 

 pations. In examining the results of the 

 whole experiments, and including all the 

 thirteen classes of men subjected to expe- 

 riment, the power of the inspiratory muscles 

 is found greatest in men of 5 feet 9 inches in 

 height, their inspiratory power being equal, on 

 an average, to a column of 2'75, and their 

 expiratory power to 3*97 inches of mercury ; 

 while in four of these classes, composed ge- 

 nerally of active, efficient, and healthy indi- 

 viduals, viz. Firemen, Metropolitan Police, 

 Thames Police, and Royal Horse Guards, 

 the inspiratory power of the men of 5 feet 7 

 inches was the greatest, being equal to 3'07 

 inches of mercury, and those of 5 feet 8 

 inches to 2'96 (nearly 3 inches). The aver- 

 age power of the 5 feet 7 inches and 5 feet 

 8 inches men of all the thirteen classes was 

 only 2 - 65 inches of mercury. The inspiratory 

 power of twelve six-feet men in the first bat- 

 talion of Grenadier Guards was only 1*92 

 inches, while that of thirty-one of the same 



* These observations of Beau and Maissiat upon 

 the differences in the respiratory movements in 

 males and females are confirmed by Dr. Hutchin- 

 son (Op. cit. p. 195), and they were known so far 

 to Boerhaave and Haller. 



f These authors also state that this difference in 

 the respiratory movements of the two sexes have 

 impressed upon the chest certain anatomical differ- 

 ences ; for while the intercostal spaces at the upper 

 part of the chest are larger in the female, those at 

 the lower part are larger in the male ; and while the 

 first rib is movable in the female, it is almost or 

 entirely immovable in the male. 



J Lehrbuch der Physiologic des Menchen, band i. 

 S. 524. 1844. 



Journal of the Statistical Society of London, 

 vol. vii. p. 193. 1844 ; and Medico-Chirurg. Trans- 

 actions of London, vol. xxix. p. 197. 1846. 



|| Der Mechanismus der Respiration und Circu- 

 lation, S. 116120. Berlin, 1845. 



height in the Blues (Life Guards) was 2'71 

 inches. He infers from these experiments 

 that a healthy man of 5 feet 7 inches or 5 

 feet 8 inches, should elevate by inspiration 3 

 inches of mercury. The force of the expi- 

 ratory muscles is more liable to be affected 

 by the ordinary occupation of the individual 

 than that of the inspiratory muscles, and 

 therefore the state of the former is less to be 

 relied upon in judging of the health of the 

 individual than that of the latter.* The elas- 

 ticity of the walls of the chest is, no doubt, 

 one cause of the greater force of the expi- 

 ratory over that of the inspiratory muscles. 



In inspiration the pressure of the elastic 

 air in the lungs causes these organs to ex- 

 pand, so as to keep their outer surface in 

 contact with the inner surface of the dilating 

 thorax ; and by this the air of the lungs be- 

 comes rarified, and a quantity of fresh air 

 rushes along the trachea and bronchial tubes 

 to restore its equilibrium ; in expiration, on 

 the other hand, the lungs are compressed, and 

 a portion of air is forced outward along the 

 same passages. In these movements the 

 lungs are not quite passive. The external 

 surface of the lungs, and of the numerous 

 lobes into which they may be divided, is 

 covered with an elastic membrane, and this, 

 conjoined with the weight of their tissues, 

 must favour the expulsion of the air during 

 expiration, and present a certain amount of 

 resistance to its entrance during inspiration.-)- 



* Valentin's experiments upon the respiratory 

 forces were performed upon six males between 18 

 and 32 years of age. In ordinary tranquil respira- 

 tion the force of each of the acts of inspiration and 

 expiration was equal to the weight of a column of 

 mercury of from 4 to 10 millimetres (or from -1574 

 to -3937 of an English inch) ; in the least forcible 

 respiration it ranged between 20, 35, and 40 milli- 

 metres of mercury (from -7874, 1-377, and 1-5748 of 

 an English inch). In ordinary tranquil respiration 

 in the same individual, at different periods, the range 

 of the respiratory force was even more than be- 

 tween 5 and 10 millimetres (or between -1968 and 

 3937 of an inch). The average force of an ordinary 

 tranquil respiration, when the nose was held and the 

 individual inspired and expired through the mouth, 

 was 6-45 mill. (-2539 of an inch) ; when they in- 

 spired through the nose and expired through the 

 mouth alone, it was 10-6 mill. (-4173 of an inch) ; 

 and when they inspired through the nose and ex- 

 pired through the nose and mouth, it was 5 mill. 

 (-1968 of an inch), or about one half of the .strength 

 when they expired through the mouth alone. He 

 found that the strongest inspiration of which these 

 individuals were capable was equal to 144*3 mill. 

 (5-6812 inches) of mercury, and the strongest expi- 

 ration to 204 mill. (8-0316 inches) of mercury. Men- 

 delssohn's experiments were performed upon seven 

 individuals, and they breathed through one nostril, 

 the other nostril and the mouth being shut. He 

 found that the force of the most powerful expiration 

 was greater than that of the most powerful inspi- 

 ration by about one inch of mercury. The most 

 powerful expirations were on an average between 

 4-4 and 4'8 inches of mercury. In performing such 

 experiments it is necessary to breathe through the 

 nose, the mouth being shut, as in those of Dr. 

 Hutchinson and Mendelssohn, if we wish to obtain 

 the force of the muscles of the chest, apart from 

 that of those of the cheeks. 



f Dr. Carson (Philos. Trans, of London for 1820, 

 p. 42), states that in his experiments on " calves, 



