280 THE VITAL FUNCTIONS. 



latter by the pulmonary veins, fill their respec- 

 tive auricles at the same instant; and both 

 auricles, contracting at the same moment, dis- 

 charge their contents simultaneously into their 

 respective ventricles. In the like manner, at 

 the moment when the left ventricle is propelling 

 its aerated blood into the aorta, for the purposes 

 of general nutrition, the right ventricle is like- 

 wise driving the vitiated blood into the pul- 

 monary artery, in order that it may be purified 

 by the influence of the air. Thus the same 

 blood which, during the interval of one pulsation, 

 was circulating through the lungs, is, in the 

 next, circulating through the body ; and thus 

 do the contractions of the veins, auricles, ven- 

 tricles, and arteries all concur in the same 

 general end, and establish the most beautiful 

 and perfect harmony of action.* 



* Evidence is afforded of the human conformation being 

 expressly adapted to the erect position of the body by the 

 position of the heart, as compared with quadrupeds ; for in the 

 latter, the heart is placed directly in the middle of the chest, 

 with the point towards the abdomen, and not occupying any 

 portion of the diaphragm ; but in man, the heart lies obliquely 

 on the diaphragm, with the apex turned towards the left side. 



