132 



VITAL FUNCTIONS. 



39:2. 'Die, two Hearts separated. The two hearts in the 

 natural state are joined together, but that the student may 

 the more clearly -comprehend the two systems, they are 

 here represented separately, Fig. 86. 



393. In this plan, d rep- Fig. 86. 

 resents the right auricle , 



e, the right ventricle; 7c, 

 the left auricle ; /, the left 

 ventricle ; a, the aorta ; i, 

 the pulmonary veins ; f 9 

 the pulmonary arteries ; 

 c, the vena cava; 6, the 

 meeting of the small bran- 

 ches of the aorta, and vena 

 cava, and h, the meeting 

 of the pulmonary veins and 

 arteries. 



394. The circulation is as , 

 follows. The blood is con- U 

 veyed by the vena cava, f, ' I 

 to the right auricle, d, and 

 poured into -the ventricle, 



e, which contracting, throws it through the pulmonary 

 artery, f 9 to the lungs, where it is oxygenated, or puri- 

 fied, and made fit for general circulation. The pulmonary 

 veins then receive, and convey it to the left auricle, /c, by 

 which it is transmitted to the ventricle, /, which contracting 

 with great power, propels it to all parts of the system 

 through the aorta a. From the small branches of the aorta, 

 it is received into those of the vena cava, by which it is 

 transmitted to the right auricle, the point where we com- 

 menced. In all the mammalia and birds, this is the 

 routine of the circulation. 



395. The two Hearts united. It only now remains to 

 show the two hearts of man united, that the pupil may ob- 

 serve how they naturally exist as a single organ in external 

 appearance. Fig. 87 represents the double heart, show- 



What are the two systems of circulation in quadrupeds and man called? 

 Describe the circulation in man. 



