Chap. 32.] [ 329 ] 



CHAP. XXXII. 



RESPIRATION' AND ANIMAL HEAT. 



Refpiration in part an ir.^johinta;-; F*8ion Fc:;r Sts-res r.f Refpira- 

 tion. U/es of Refpiration. Rffpiraiion of Iiif tis different from 

 that cf other Animals. Tkt red 'Colour of the Blood derived from the 

 Air in Refpiratic/i. Dr. Prig/Heft Experiments. ~ Dr. Goodnvyn's 

 Experiments. The oxygenous Part of the Air dimi>..jl:-i.d by Refpi- 

 ration. Fixed Air generated in thz Lungs in Refpiration and 

 expired, Animal Heat produced by Refpiration. Inftanced in 

 different Animals. Dr. CfOfwfortTs ingenious Theory. 



T TNINTERRUPTED refpiration being neceflkry 

 \^J to our exiftence, it is wifely ordained, that this 

 function Ihould be fo far involuntary as not to require 

 a continual and irkfome attention. For other pur- 

 pofes, as that of fpeech, refpiration is no lefs wifely 

 fubmitted in fome meafure to our direction, fo that 

 within certain limits we can accelerate or retard it .an 

 pleafure. We are fufficiently prevented, however, ; 

 from fulpending. refpiration to fuch an extent as to in- 

 terfere with other procefies abfJlutely neceffary tu the 

 fupport of life, by being fubjected, whenever we ce^fe 

 to breathe, to a fenfation inexpreflibly diftreffing, and 

 which compels us to ufe every effort in our power to 

 inhale air into the lungs. 



The thorax, or that bony cafe which furrounds and 

 protects the lungs, is furniflied with a number of 

 mufcles, fome of which, by drawing. the ribs upwards, 

 enlarge its capacity, and others, by drawing them 

 downwards, diminifh it. Its capacity, however, is ftill 

 more influenced by the mufcular organ called the dia- 

 phragm, which from the breaft bone and lower ribs 



pa fifes 



