407 



the finest bronchi. Krause, Henle and Schäfer make the statement 

 that glands disappear in bronchi 1 mm diameter; Stöbr in bronchi 

 0,5 mm in diameter. 



In obtaining my own results sections from the lung of the cat 

 were studied in both longitudinal and transverse sections of the bronchi, 

 the largest of which were about 2 mm in diameter. The longitudinal 

 sections were cut slightly thicker than the transverse sections. All 

 showed the cartilage and glands well, but the transvers were more 

 favorable for the study of cilia and goblet cells. 



Cartilage. The longitudinal sections showed very well the dis- 

 tribution of the cartilage in the bronchi. The plates were bent part- 

 ways around the bronchus, so that in some places the same plate was 

 cut in two places. In those bronchi where cartilage is present, plates 

 are always found at the angle formed by the union of bronchi. In 

 the sections examined they could always be seen. The cartilage is 

 found between the fibro-elastic tunic and the muscle layer, although 

 in some places the glands were between the muscle and the cartilage. 

 The glands were even seen in a few places to extend over the car- 

 tilage so as to entirely cover it. The cartilage was found to disappear 

 in bronchi of about 1 mm diameter. This observation was made on 

 bronchi cut longitudinally. Other observations were made to determine 

 the point of disappearance in sections cut transversely. Here it was 

 found to be in bronchi 0,94 mm in diameter. These results confirm 

 the observations of Kölliker who says cartilage disappears in bronchi 

 of about 1 mm in diameter. But Frankenhauser says that he has 

 found cartilage in bronchi 0,4 mm diameter so here there is quite a 

 discrepancy. The observations of these two men were made on the 

 lung of man. 



The pieces of cartilage observed in all the sections examined were 

 on the edge of the muscle layer, but a thin sheath of muscle extends 

 around so as to inclose them completely. 



Goblet cells. These like the cilia are abundant in the larger 

 bronchi. In places in the sections examined they were so numerous 

 that the greater part of the epithelium were goblet cells. This was 

 due not merely to the number but to the way in which the goblet 

 cells occur. 



They are placed in nests varying in number and size according 

 to the size of the bronchus. In the larger bronchi the cells are larger, 

 and the patches contain more cells than they do in the finer bronchi. 

 The goblet cells did not seem to have any relation to the glands, or 

 to the ciliated epithelium, except that they disappeared almost simul- 



