156 THE LYMPHATIC SYSTEM 



the organ in. the form of invaginated funnel-shaped depressions, 

 the crypts ("follicles" of the tonsils). The ducts of many mucous 

 glands open into the recesses of these branching crypts. The 

 mucus secreting glands lie in the loose connective tissue which 

 surrounds the tonsil on all but its faucial surface. The crypts are 

 lined throughout by a layer of stratified epithelium, which is con- 

 tinuous with that on the free surface of the tonsil, but which 

 becomes progressively thinner as it recedes into the deeper recesses 

 of the crypts. 



Many of the lymphatic corpuscles migrate into the intercellu- 

 lar spaces of the epithelial layer, and even penetrate to the free 

 surface ; thus they find their way into the oral cavity, where they 

 are found in large numbers in the saliva, as " salivary corpuscles" 

 If such salivary corpuscles are examined in a drop of saliva, freshly 

 prepared, the fine intracellular granules of the polynuclear leuco- 

 cytes will be seen to undergo an active dancing movement, Brow)i- 

 ian motion. The salivary corpuscles are derived not only from 







FIG. 152. FROM A CRYPT OF A DOG'S TONSIL. 



a, stratified epithelium ; 6, basal margin of the epithelium ; c, infiltration of the epi- 

 thelium by leucocytes ; d, spaces in the epithelium filled with leucocytes and epithelial 

 cells ; e, blood vessel ; /, lymphoid tissue, x 150. (After Bohrn and von Davidofi'J 



the faucial tonsils but from the other lymphoid tissue which is in 

 relation with the oral mucous membrane, e. g., the lingual and 

 pharyngeal tonsils. 



The passage of leucocytes through the epithelial surface of the 

 faucial tonsil is so very active that at times the epithelium becomes 

 completely filled with these cells, and it is then difficult to distin- 

 guish it from the adenoid tissue beneath. 



