504 THE HEART. 



many ounces.* It is naturally transparent, but slightly tinged 

 with red in children, and yellow in old persons. It is often 

 slightly tinged with red in persons who have died by violence. 



Of the Heart. 



The great organ of the circulation consists of muscular 

 fibres, which are so arranged that they give it a conical form, 

 and compose four distinct cavities within it. 



Two of these cavities, which are called Auricles, receive the 

 contents of the veins ; the other two communicate with the 

 arteries, and are called Ventricles. 



The auricles form the basis of the cone ; the ventricles the 

 body and apex. 



The structure of the auricles is much less firm than that of 

 the ventricles, and consists of a smaller proportion of muscular 

 fibres. They appear like appendages of the heart, while the 

 ventricles compose the body of the viscus. 



The ventricles are very thick, and are composed of muscular 

 fibres closely compacted. 



The figure of the heart is not regularly conical ; for a portion 

 of it, extending from the apex to the base, is flattened ; and 

 in its natural position, this flat part of the surface is down- 

 wards. 



It is placed obliquely in the body ; so that its base presents 

 backward and to the right, and its apex forward and to the 

 left. 



Notwithstanding this obliquity, the terms right and left are 

 applied to the different sides of the heart, and to the different 

 auricles and ventricles ; although they might, with equal pro- 

 priety, be called anterior and posterior. 



/ The two great veins called Vena Cavce, which bring the 



blood from every part of the body, open into the right auricle 



\ from above and below ; the right auricle opens into the right 



* The pericardium has been so distended, by effusion in dropsy, that it has 

 formed a tumour, protruding on the neck from under the sternum. This 

 tumour had a strong pulsating motion. It disappeared completely when the 

 other hydropic symptoms were relieved. 



