OF NATURAL HISTORY. 107 



Refplration, befide being the probable caufe of the equable conti- 

 nuation of heat in animals, produces many other falutary and ufeful 

 eflFe£ts in the oeconomy of animated bodies. There is a moft inti- 

 mate connedkion between the adt of refpiring and the circulation of 

 the blood. When refpiration is, for a fhort time, interrupted by 

 the fumes of burning fulphur, by mephitic air, or by remaining fome 

 minutes under water, the adion of the heart ceafes. But, in many 

 cafes of this kind, the motion of the heart may, and frequently has 

 been renewed, by blowing air into the lungs, and by the application 

 offtimulating fubftances to different organs of the body. In per- 

 fons feemingly dead from a temporary fufpenfion of refpiration, if 

 the lungs can be excited to adt, the motion of the heart inftantly 

 commences, the circulation of the blood is reftored, and life is re- 

 covered. This intimate connexion between refpiration and the ac- 

 tion of the heart, is one of thofe aftonifhing fads in the animal oe- 

 conomy, the caufes of which will perhaps forever elude the keenelt 

 refearches of the human intelled. All we know is, that certain 

 fundlions are indifpenfible to the exiftence of animals, and that, if 

 any of them are fufpended for a few feconds, life is extinguifhed j 

 namely, the adion of the brain and nerves, the circulation of the 

 blood, refpiration, and a probable refult of refpiration, animal heat. 

 Thefe fundions, from their importance in the fyftem', have received 

 the appellation of vital funSiions. There are other fundions of the 

 body, called natural, which are no lefs neceflary to life, as the di- 

 geftion and concodion of aliment, the various fecretions and excre- 

 tions. But they are diftinguifhed from the vital fundions, becaufe 

 fome of them may be fufpended for a confiderable time without 

 materially injuring the body. 



O 2 Refpiration 



Theory of Animal Heat, he may confult Doftor Gardiner's Obfervathns on the Animal 

 Oeconomy, and on the Caufes and Cure of Dfeafes, an ingenious and ufeful performance, 

 lately publifhed, and which merits much more attention from Philofophers and Phy- 

 ficians than it has hitherto received. 



