252 



THli VITAL FUNCTIONS. 



the left ventricle (l) the blood is propelled into the 

 359 ^^-^^^ aorta (a) to be diffused 



through the arteries of 

 the system (b) to every 

 part, and penetrating into 

 all the capillary vessels ; 

 thence it is returned by 

 the veins, through the ve- 

 nae cavae (c), to the right 

 auricle (d), which delivers 

 it into the right ventricle 

 (e). This right ventricle 

 impels the blood, thus re 

 ceived, through the pulmonary arteries (f), into the 

 lungs at (h), where it is aerated, and whence it is 

 reconveyed by the pulmonary veins (i), into the 

 left auricle (k), which immediately pours it into the 

 left ventricle (l), the point from whence we set out. 

 Both the right and the left heart have their re- 

 spective auricles and ventricles ; but they are all 

 united in one envelope, so as to compose in appear- 

 ance but a single organ :* still, however, the right 



* A remarkable exception to this general law of consolidation 



occurs in the heart of the Dugong, 



360 ^%>|^^ ys^ represented in Fig. 360, in which it 



may be seen that the two ventricles, 

 ( E and l), are almost entirely de- 

 tached from each other. In this 

 figure, which is taken from the Phi- 

 losophical Transactions for 1820, d 

 is the right or systemic auricle ; e 

 the right or pulmonary ventricle ; f 

 the pulmonary artery ; k the left or 

 pulmonary auricle ; l the left or sys- 

 temic ventricle ; and a the aorta. A 

 similar separation of the ventricles though not to the same extent, is 

 observed in the apex of the heart of the Manati, (Trichechus ma- 

 natus.) 



