582 SPECIAL HISTOLOGY. 



from the walls of the bronchia and bloodvessels, particularly those of 

 the pulmonary arteries, running with those canals through the substance 

 of the lung, and through some minute lymphatic glands (glandulce 

 pulmonales), towards the root of the lung, in order, ultimately, to com- 

 municate with the larger bronchial glands. 



The nerves of the lungs are derived from the vagus and sympathetic, 

 form the more scanty plexus pulmonalis anterior, and the richer plex. 

 p. posterior, and are distributed principally with the bronchia? and the 

 pulmonary artery, occasionally, however, accompanying the pulmonary 

 veins and vasa bronchialia. In the interior of the lung they are also 

 furnished with microscopic ganglia, and may be traced nearly to the 

 termination of the bronchice. 



It is very remarkable, that besides the air-cells, some other parts of 

 the lungs are also supplied by the vasa pidmonalia, such as the surface 

 of the lungs and the finer bronchia*. With respect to the former, even 

 in uninjected lungs, minute ramuscules of the pulmonary artery are 

 apparent in various situations on the surface of the lungs, ramifying 

 under the pleura. Reisseisen (p. 17) describes these vessels, and figures 

 them very beautifully (Table IV., Y.) ; recently, Adriani has traced 

 them in injected lungs and states that they penetrate into the interior, 

 much convoluted and frequently anastomosing ; they are considerably 

 thicker, however, and form wider plexuses than those of the alveoli. 

 The blood from these plexuses is conveyed away, on the one hand, by 

 the superficial roots of the pulmonary veins, and, on the other, through 

 anastomoses with the ramifications of the vasa bronchialia in the pleura 

 pulmonalis. That the pulmonary artery also supplies the bronchice to 

 some extent was stated by Arnold (Anat. II., p. 171) ; and to Adriani 

 we are indebted for more precise information on this interesting subject. 

 According to them, the pulmonary artery and veins chiefly participate 

 in the formation of the capillary plexus on the surface of the bronchice, 

 which is characterized by the elongated form of its meshes, and is con- 

 stituted by vessels almost as fine as those of the air-cells (in Man, of 

 0-004-0-006 of a line), whilst the bronchial vessels are specially destined 

 for the supply of the muscular and fibrous coats of those canals. It is 

 comprehensible, also, that in this situation the two vascular systems are, 

 to a certain extent, connected ; and consequently the older anatomists, 

 such as Haller, Sommering, and Reisseisen, who speak of a connection 

 between the two vascular systems of the lungs, were quite right. Ac- 

 cording to Adriani and Rossignol, the bronchial arteries and veins may 

 be injected from the pulmonary veins, and inversely, the pulmonary 

 veins from the bronchial arteries ; but the bronchial vessels cannot be 

 filled from the pulmonary arteries. 



In accordance with these facts, a participation in the interchange of 

 gases may be ascribed also to the finest bronchice, but, on account of the 



