THE HEART 



43 



no direct communication with one another. Each <>{ 

 these two great cavities is further subdivided, nut 

 longitudinally but transversely, by a movable partition. 

 The cavity above the transverse partition on each side is 

 called the aiiricle; the cavity below, the ventricle — rit;ht 

 or left as the case may be. 



Each of the four cavities has the same capacity, and is 

 capable of containing from 4 to 6 cubic inches of water 



J5^ ^■^^.■v, ! 'FV. 



T^r. 



Fig. 14. — The Heart, Great Vessels, and Lungs. (Front View.) 



R. V. right ventricle ; L. V. left ventricle ; R.A. right auricle ; L.A. left 

 auricle; Ao. aorta; P. A. pulmonary artery ; P. r. pulnionary veins; 

 R.L. right lung; L.L. left lung; f..S^ vena cava superior; .^'.C. sub- 

 clavian vessels ; C. carotids ; R.J. V. and L.J. V right and left jugular 

 veins ; V. I. vena cava inferior ; T. trachea ; B. bronchi. 



All the great vessels but those of the lungs are cut. 



(70 to 100 cubic centimeters). The walls of the auricles 

 are much thinner than those of the ventricles. The wall 

 of the left ventricle is much thicker than that of the 

 right ventricle ; but no such difference is perceptible 

 between the two auricles (Figs. 16 and 17, 1 and 3). 



