STRUCTURE OF HEART 



takes this direction and not the other, and how does it make 

 its way from the artery of a given organ into the vein ? 



Internal Structure of the Heart, To answer the first 

 question why the blood leaves the heart by the arteries 



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syst.tr 



C.a,rt 



FIG. 22. The heart of the Frog frc 



and returns to it by the veins, and not vice versa we must 

 examine the heart itself in some detail. 



The ventricle is a hollow structure with thick spongy walls 

 and a small cavity (Fig. 22, vt\ and there are two perfectly 



