RESPIRATION. 215 



The power of excitement of the surface to cause inspiration has 

 been shown by Beclard and others, who, on mechanically irri- 

 tating foetal kittens still enclosed in the membranes, found in- 

 spiratory efforts take place at each irritation. 



" The alternate motion of the chest continues, during health 

 and freedom from restraint, from the moment of birth till death. 

 Its object is, that the lungs may be expanded to admit the air, 

 and contracted to expel it, in perpetual alternation. This alter- 

 nation occurs, in an adult at rest, about 14? times in a minute, 

 once to about five pulsations of the heart." 1 



" For man, in common with all warm-blooded animals, cannot 

 long retain the inspired air, but is compelled to discharge it and 

 take in a fresh supply of this pabulum of life, as it always has 

 been denominated. 15 Common observation teaches, that, how- 

 ever pure may be the air entering the lungs, it instantly under- 

 goes remarkable changes, by which it is contaminated and 

 rendered unfit for another inspiration, unless it is renewed. * 



The common quantity of air taken in at each inspiration is 

 about 16-5 cubic inches; and the quantity remaining after death 

 in the lungs of a stout adult man, about 100 cubic inches, accord- 

 ing to Allen and Pepys. Dr. Bostock, agreeing with Dr. Menzies 

 and many others, believes 40 cubic inches to be the average inspir- 



1 But this varies in different individuals, and in disease. When there is dis- 

 ease of the heart, with excitement, the proportion of the heart's action is greater 

 than natural ; and where of the lungs or pleura, the proportion is on the side 

 of respiration. But the action of both the heart and respiratory organs is increased 

 in the affections of either. I have at this moment a young female patient, in 

 whom, through a nervous affection, I always find the respirations 98 and the 

 pulse 104. My clinical clerk says he has found the respiration 106 and the 

 pulse 104. The inspirations are shallow. She is in no danger. The quickest 

 pulse I have ever felt has been 208, counted easily at the heart, though not at the 

 wrist. In the two middle-aged men in whom I observed this, there was merely 

 morbid irritability of the heart, and they walked about and ate like other people, 

 though indisposed. One is now very well. 



k " The antiquity of the notion that air is the pabulum mice is seen in the book 

 de Flatibus, usually ascribed to Hippocrates. The author regards the aliment as 

 threefold, victuals, drink, and air ; but the latter he calls vital, because we 

 cannot, for a moment, dispense with a supply of it without danger to life." 



1 " Consult Harvey's Dispute upon the necessary renovation of the aerial succus 

 alibtiis, with the celebrated Astronomical Professor, J. Greaves, in th.9 latter's 

 Description of the Pyramids in Egypt, p. 101. sq. Lond. 1646. 8vo. 



Also the popular Edm. Halley's immortal Discourse concerning the Means of 

 f urni<ihing Air at the Bottom of the Sea in any ordinary Depths. Phil. Trans. 

 vol. xxix. No. 349. p. 492. sq." 



