154 MICROSCOPIC ANATOMY OF THE ORGANS. 



present in the gland, and run as fine branches into the fol- 

 licles. Ganglion cells are rarely found. 



9. COCCYGEAL GLAND (GLOMUS COCCYGEUM). 



This organ is situated on the arteria sacra lis media. Its 

 general structure resembles that of the carotid gland. The 

 same polygonal epithelioid cells are found, and these stand in 

 the same close relation to the blood-vessels. Small branches 

 of the median sacral artery enter the gland and break up into 

 a capillary network. In the capillaries that make this up there 

 are peculiar dilatations mainly situated on the venous side of 

 the network. 



All the glands that have been described in this section must 

 be considered as made up primarily of two parts, namely, a 

 connective-tissue framework, and a cellular part contained in 

 the meshes of this framework. The cellular part is divided in 

 each case into masses of cells (follicles or lobules), which have a 

 similar and complete structure of their own. By the repetition 

 of these follicles the organ is built up. The connective- tissue 

 framework of the gland is in every case closely connected with 

 the blood supply. The vessels follow, to a certain extent, the 

 course of the trabeculse and connective-tissue strands, which 

 divide the organ into units. The cellular units (follicles or 

 lobules) correspond often to blood vascular units, in which the 

 artery usually enters the centre of the follicle and breaks up 

 into capillaries which join with the veins at the periphery of 

 the follicle. The arteries and veins are always as far apart in 

 the follicle as possible. All these glands, then, are composite 

 structures, so that in their study we should consider riot only 

 the units themselves, but also the relation of these units to one 

 another and to the framework. 



II. DIGESTIVE SYSTEM (ALIMENTARY TRACT). 



The whole alimentary tract is lined will) mucous membrane. 

 This is a soft membrane consisting of epithelium, glands, and 

 connective tissue. The epithelium consists of one or more 



