508 



OF RESPIRATION 

 Fig. 145. 



A view of the Bronchi and Bloodvessels of the Lungs as shown by dissection, as well as the relative posi- 

 tion of the Lungs to the Heart : 1, end of the left auricle of the heart ; 2, the right auricle ; 3, the left ven- 

 tricle with its vessels ; 4, the right ventricle with its vessels; 5, the pulmonary artery ; 6, arch of the aorta; 

 7, superior vena cava; 8, arteria innominata; 9, left primitive carotid artery; 10, left subclavian artery; 11, 

 the trachea ; 12, the larynx ; 13, upper lobe of the right lung ; 14, upper lobe of the left lung; 15, trunk of 

 the right pulmonary artery ; 16, lower lobes of the lungs. The distribution of the bronchi and of the 

 arteries and veins, as well as some of the air-cells of the lungs, is also shown in this dissection. 



Fig. 146. 



each; by which provision the full in- 

 fluence of the air upon it is secured. 

 The network of vessels (Fig. 146) is 

 close, that the diameter of the 



so 



meshes is scarcely so great as that of 

 the capillaries which enclose them; 

 indeed, it would be impossible to con- 

 ceive of a method, by which blood, 

 whilst still retained within vessels, 

 should be spread over a larger sur- 

 face for aeration. And if not re- 

 stricted within vessels, it could not 

 be ceaselessly and rapidly driven on 

 by the propulsive power of the heart, 

 which acts no less efficiently upon 

 the pulmonary circulation than upon 

 the systemic, although the force ex- 



erted is much inferior, the resisting power being far less, in consequence of the 



shortness of the circuit. 



[M. Rossignol has recently given an elaborate description of the pulmonary 



Arrangement of the Capillaries of the Air-cells of the 

 Human Lung. 



