814 



THE TONSILS. 



between the palatine arches, presents from twelve to fifteen orifices, which 

 give it a perforated appearance. These orifices lead into recesses in the 

 substance of the tonsil, from which other and smaller orifices conduct still 



Fig. 571. Fig. 571. SECTION OP A FOL- 



LICULAR GLAND FROM THE 

 ROOT OP THE TONGUE (from 

 Kolliker). M 



a, epithelial lining ; 6, papil- 

 lae of the mucous membrane ; c, 

 outer surface of the capsule, 

 formed of connective tissue : d, 

 outlet, and e, cavity of the cap- 

 sule ; g, follicles in the substance 

 of the capsular wall. 



deeper into numerous fol- 

 licles. These follicles are 

 lined by the epithelium and 



papillary mucous membrane of the throat, and have thick walls formed 

 by a layer of closed capsules imbedded in the submucoua tissue. The cap- 

 sules, which may be compared to those of Peyer's glands of the intestine, 

 besides having a mesh-work of capillary blood-vessels and delicate trabecular 

 tissue within them, are filled with consistent greyish substance, containing 

 cells and free nuclei, but without the characters of mucus. A substance having 

 the same microscopic elements is found in the cavity of the follicle, but 

 here it is liable to be mixed with mucus supplied by true mucous glands, 

 the ducts of which pass into the follicle. The function of the tonsils is as 

 little known as that of the other glands formed of closed capsules which 

 are found in the mucous membrane of the alimentary canal. 



FollicuJar recesses, surrounded by closed capsules, like the recesses and 

 capsules of the tonsils, are also found at the root of the tongue, where they 

 form a layer extending from the papillae vallatse to the epiglottis, and from 

 one tonsil to the other, lying immediately beneath the mucous membrane 

 and above the mucous glands, many of whose ducts they receive. 



The tonsils receive a very large supply of blood from various sources, viz. from the 

 tonsillar and palatine branches of the facial artery, and. from the descending palatine, 

 the ascending pharyngeal and the dorsalis linguae. From these arteries, fine branches 

 and capillaries are distributed abundantly to the walls of the capsules and to the 

 papillae of the mucous membrane lining the follicles. The veins are numerous, and 

 enter the tonsillar plexus on its outer side. The nerves come from the glosso- 

 pharyngeal nerve, and from the fifth pair. 



THE SALIVARY GLANDS. 



The saliva, which is poured into the mouth, and there mixed with the 

 food during mastication, is secreted by three pairs of glands, named from 

 their respective situations, parotid, submaxillary, and sublingual. Agreeing 

 in their general physical characters and minute structure, these glands difier 

 in their size, form, and position. 



The Parotid Gland. 



The parotid is the largest of the three salivary glands. It lies on the side 

 of the face, in front of the ear, and extends deeply into the space behind 

 the ramus of the lower jaw. Its weight varies from five to eight drachms. 



