3 82 



BRONCHIAL TUBES AND AIR-CELLS. [sect. 176. 



plexus, and were probably given off chiefly by the vagus. — 

 Peculiar appendages of the pleura, resembling the villi of the 

 synovial membranes, and containing vessels and even nerves, 

 occur here and there, according to Luschha, at the sharp edges of 



the lungs. 



Fig. 158 



§ 176. Bronchial-tubes and Air-cells. — When the right and 

 left bronchi have arrived at the roots of the lungs, they com- 

 mence to ramify after the manner of the excretory ducts of a 

 large gland ; the liver for example. They become divided into 

 smaller and smaller branches, mostly dichotomously and at acute 

 angles ; but small branches are also given off at right angles from 

 the sides of the larger tubes. On reaching a certain size, all the 

 bronchial tubes break up into tufts, and form a very thick tree, 

 the finest ramifications of which never join each other. This ex- 

 tends throughout the whole lung, upon the surface and in the 

 interior alike. 



With the smallest bronchial tubes or bronchia are connected the 

 ultimate elements of the air-passages — the air-cells or pulmonary 

 vesicles (vesicula s. cellulce atrea. s. Malpighiance, alveoli puhnonum, 

 Rossignol). The terminal bronchial tube is connected with an entire 

 group of vesicles, and not (as was formerly believed) by the ending 

 of each in a single vesicle. The groups of vesicles correspond to the 



smallest lobules of racemose glands, 

 and there is, accordingly, not the 

 slightest necessity to designate them 

 by another name, as Rossignol has 

 done, who calls them 'infundibula.' 

 Still it must be admitted, that their 

 structure presents certain peculi- 

 arities. Thus, in other glands, the 

 gland-vesicles have a certain inde- 

 pendence, even if they are not en- 

 tirely isolated ; but the air-cells of 

 the lung, which are the elements 

 corresponding to gland-vesicles, are 

 blended with each other to a con- 

 siderable degree, so that the vesicles 

 belonging to a lobule do not open 

 separately into ramifications of the 

 small bronchi, but join together into 

 a common cavity, from which the air-passage is evolved. We 



Two small pulmonary lobules, an, 

 with the air-cells, bb, and the finest 

 bronchial branches, cc, on which air- 

 cclls are likewise seated, of a newly born 

 infant; magnified - 2"> times. Half-dia- 

 grammatical figure. 



