258 



MANUAL OF IIISTOLOGY. 



lined with cubical epithelium. Owing to the distention of some 

 of the gland-cells by mucus or by the action of reagents, they 

 assume a rounded form, and the nuclei are pressed against the 

 attached ends of the cells. Such corpuscles are known as 

 4 'goblet " cells. Some of the larger glands project posteriorly 

 outside of the fibrous membrane, but the great majority of them 

 are situated internally to that structure, and then form a dis- 

 tinct layer, the "glandular layer." They are most abundant 

 in the spaces between the cartilages. Their ducts pierce the 



deb 



Pio. 109. Transverse section of bronchial twig, 6 mm. in diameter : a. outer fibrous layer ; ft, muscu- 

 lar layer ; c, inner fibrous layer (inucosa) ; rf. epithelium. Magnified 30 diameters. F. E. Schulze. 



mucous membrane obliquely, so that the entire length of a 

 duct is not usually found in a section of the tracheal wall. 

 At short intervals, between the columnar cells of the surface, 

 other cells are found, of a spindle shape, or somewhat stellate. 

 These cells send processes upward to the surface and down- 

 ward into the basilar membrane, where they become contin- 

 uous with other branched cells. The prolongation which passes 

 upward to the surface is usually single, though it may occasion- 

 ally send off a delicate filamentary branch, which is lost in 

 the cement substance between adjacent cells. 



The process, sometimes double, which passes downward 

 connects with a tissue in the mucosa which resembles the 

 lymph canalicular system of other parts. It is made up of 

 a network of branched cells, or connective-tissue corpuscles, 

 which line a series of spaces, that in turn communicate with 

 the lymphatic capillaries of the mucous membrane. Sikorsky 

 injected a watery solution of carminate of ammonia into the 



