LUNGS. 59 



which accompany the branches of the pulmonary artery and vein ; (3) the peribronchial 

 lymphatics which occur in the adventitia of the bronchi, communicate freely with the peri- 

 vascular lymphatics, and run towards the bronchial glands. In the walls of the bronchi of 

 the cat large masses of adenoid tissue or lymph-cords are easily found (Klein, Sanderson, and 

 Stirling). They are not nearly so abundant in the human lung. 



PREPARATION. The lymphatics of the bronchi may be injected by the puncture method ; 

 but a good idea of their arrangement may be obtained by the student from the lungs of a 

 coal-miner who has suffered from anthracosis. The particles of soot and charcoal are 

 carried into the lymphatics, which therefore appear black. Make a vertical section through 

 the pleura and lung-tissue of such a lung, which has been hardened in alcohol, and mount it 

 in Farrant's solution. 



EXAMINATION (L). Observe the black pigment distributed in the lung. Note that the 

 superficial layer of the pleura has no pigment in it, though the deep layer is markedly pig- 

 mented. Valves prevent the passage of the pigment from the deep into the superficial 

 lymphatics of the pleura. Trace from the pleura inwards strands of pigment in the inter- 

 lobular septa, in the outer coats of the arteries and bronchi, and it may be seen here and there 

 between the air-vesicles, and also in the adventitia of the bronchi and arteries. (Compare 

 Klein's 'Anatomy of the Lymphatic System,' pt. ii., 1875.) 



The Nerves of the Lung are very numerous, and enter it with the bronchi. As already 

 indicated, they may be seen in a section of the root of the lung. They lie outside the 

 cartilages in the bronchial adventitia, and are accompanied by branches of the bronchial 

 arteries. Five or six strands of nerve-fibres may be found in one section. Many ganglia 

 (Remak, Klein, and Stirling) are found in their course, and are often seen in section. They 

 can be easily isolated from a bronchus with the aid of a dissecting microscope (p. xxxv). 



The Nerves of the Trachea. I have recently discovered a large number of ganglia inter- 

 calated in the course of the nerves, lying just outside the posterior muscular wall of the trachea. 

 Some of them may be seen in sections of the trachea. 



i a 



