HISTOLOGICAL DEMONSTRATIONS. in 



close to the pulmonary vessels and bronchi. The ganglia may also be 

 isolated by cutting out a portion of the wall of a bronchus of a lung 

 prepared as above, and, with the aid of a dissecting microscope, the 

 small ganglia lying outside the cartilages may easily be isolated. (W. 

 Stirling. ) 



1 8 1. Structure. An unstained section of the lung of 

 cat across a minute bronchus, made as above described. 

 Mount in Farrants' solution, or in glycerine, and examine. 



(L.) Notice the general appearance of the section ; the 

 T. S. bronchus with two or three plates of cartilage cut 

 across ; the larger vessels, the pulmonary artery having a 

 thicker wall than the vein; the air vesicles somewhat 

 collapsed. 



(H.) The air vesicles. The somewhat indefinite fibril- 

 lated tissue with numerous elastic fibres, of which the 

 alveolar walls principally consist, will be easily recognised, 

 and also the rounded nuclei of the simple layer of squamous 

 epithelium, with which the alveolus is lined. Capillaries may 

 be found cut across here and there between the alveoli. 



The bronchus. Internally, ciliated epithelium ; and ex- 

 ternally, plates of hyaline cartilage imbedded in a fibrous 

 membrane. The bronchial glands lie chiefly between the 

 two, but often the sacs of the glands pass between the car- 

 tilaginous plates, and occupy a position external to them. 

 Circular non-striped muscular fibres, difficult to recognise 

 as such, lie near to the epithelium. Around the glands 

 there is either fibrous or adenoid tissue. The latter is 

 abundantly found in the bronchial mucous membrane, 

 either diffuse or in the form of cords, which, according to 

 Klein, have a longitudinal direction. The cut ends of the 

 elastic fibres that run longitudinally along the bronchi close 

 to the epithelium may also be seen. They are most readily 

 detected in a section stained with logwood. With L. they 

 are seen as bundles causing ridges on the mucous membrane. 



The sections of the pulmonary arterioles and veinlets 

 may also be examined. 



The internal ganglia of the lung may also be found in 

 this preparation. As Remak pointed out, they are placed 

 on the nerves that accompany the bronchi. The cells are 

 large and multipolar. ( W. Stirling.} 



