Chap, xii.] SIMPLE LYMPHATIC VESSELS. 95 



shorter folds into the substance within. Numbers of 

 mucus-secreting glands situated outside the layer of 

 lymph follicles discharge their secretion into the pits 

 the crypts between the folds. The free surface of the 

 tonsils and the crypts is covered or lined respectively 

 with the same stratified epithelium that lines the oral 

 cavity. Numbers of lymph corpuscles constantly, in 

 the perfectly normal condition, migrate through the 

 epithelium on to the free surface, and are mixed with 

 the secretions (mucus and saliva) of the oral cavity. 

 The so-called mucous or salivary corpuscles of the 

 saliva, taken from the oral cavity, are such discharged 

 lymph corpuscles. They become swollen up by the 

 water of the saliva, and assume a spherical shape. 

 They finally disintegrate. 



Similar relations, only on a smaller scale, obtain 

 at the root of the tongue. 



The pharynx tonsil of Luschka, occurring in the 

 upper part of the pharynx, is in all essential respects 

 the same as the palatine tonsil. Owing to large parts 

 of the mucous membrane of the upper portion of the 

 pharynx being covered with ciliated columnar epithe- 

 lium, some of the crypts in the pharynx tonsil are also 

 lined with it. 



125. The lenticular glands of the stomach are 

 single lymph follicles. 



The solitary glands of the small and especially 

 the large intestine are single lymph follicles. 



The agminated glands of the ileum are groups 

 of lymph follicles. The mucous membrane containing 

 them is much thickened by their presence, and repre- 

 sents a Peyer's patch or a Peyer's gland. 



126. In most instances the capillary blood-vessels 

 form in the lymph follicles meshes, arranged in a more 

 or less radiating manner from the periphery towards 

 the centre ; around the periphery there is a network 

 of small veins. A larger or smaller portion of the 



