DISEASES OF THE HEART AND BLOOD, ETC. 



353 



CHAPTER XV. 



DISEASES OF THE HEART AND BLOOD, ETC. 



The accompanying cut is, of course, imaginary, but it ad- 

 mirably conveys to the mind, through the eye, the general 

 plan of the circulation as it exists in man and all the higher 

 types of animals. Both the general and 

 the pulmonary circulations are here rep- 

 resented. It will well repay the reader 

 not thoroughly familiar with at least the 

 outlines of anatomy and physiology, to 

 turn back to Chapter II, and carefully go 

 over the sections on the blood-vessels and 

 the heart, in connection with this illus- 

 tration. By this means he may perma- 

 nently fix in his memory some of the most 

 important facts and principles, that are 

 taught in the entire range of the two 

 sciences referred to. 



PLAN or THE CIBCTTLATIOV. 



The arrows indicate the direction in which the blood flows in the diflferent- 

 vessels. Those of the latter, which convey the pure or arterialized blood, are 

 indicated by the absence of all shading; and those which convey impure or 

 venous blood are represented by heavy shading. 



A, Capillaries on the general surface in all parts of the body, forming the in- 

 tricate net-work of minute vessels by which the veins and arteries- 

 are connected. 



£, One of the vena cavae, which are the two great veins through which all the 

 venous blood in the body is finally returned to the right auricle of 

 the heart. 



(7, The right auricle, from which the venous blood passes into the right ven- 

 tricle. 



Df The right ventricle, from which the venous blood passes into th« pulmonary 

 arien/. 



E, The pulmonary artery, which carries the still impure or venous blood tot 

 the lungs. 



Ff The capillaries of the lungs, spread out over the immense extent of surface 



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