THE MECHANISM OF THE CIRCULATION 



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One of these hearts, the right, forces the blood through the pulmonary 

 artery to the lungs, from whence, by the pulmonary veins, it returns to 

 the left heart. The right heart is therefore called the pulmonary heart, 



and is the effective agent in the lesser or pulmonary circulation. The 

 left heart is by far the stronger of the two hearts, and drives the blood 

 through the aorta and its branches over the system at large, from wh, 

 it is returned to the right heart by two large veins (ven* cavse). 



