20 IMMUNITY IN HEALTH 



closed in a connective tissue capsule. Laterally it rests 

 upon the superior constlrictor of the pharynx. The 

 greater portion of the free surface tends to bulge in- 

 wards, but at the upper part is a small depression 

 thinly surrounded by lymphoid tissue (Hett). This 

 used, wrongly, to be known as the swpratonsillar fossa 

 but should be called the tonsillar recess.^ From the free 

 surface some ten to twenty crypts or lacunae pass into 

 the tonsil and reach almost to the capsule (Foster, 

 1912). During deglutition the two faucial tonsils are 

 squeezed towards the middle line thus coming into in- 

 timate contact with the saliva, the mucus or the bolus 

 of food.t 



The lingual tonsil includes the small masses of lym- 

 phoid tissue at the posterior part of the dorsal surface 

 of the tongue. This part also is pressed into close con- 

 tact with any swallowed material. The crypts are said 

 to be lined with columnar epithelium, partly ciliated 

 and partly goblet cells (Browne), but the sections I 

 have seen showed stratified epithelium only. (See also 

 Sobotta.) 



The nasopharyngeal tonsil hangs in thick folds from 

 the roof and posterior wall of the nasopharynx. A 

 specially deep cleft separates the right and left halves 

 of the organ. The epithelium covering it is ciliated 

 columnar or stratified in type. Mucus from the nasal 



* It is possible that we should homologise the tonsiUar sinus in 

 man running forwards deep to the plica triangularis and not the 

 supratonsillar fossa with the tubular part of the tonsil in such animals 

 as the rabbit. (See Chapter VIII.) 



t Dr. Griffith thus expresses it :— "Bacteriology teaches that germs 

 of pneumonia, influenza, diptheria, tuberculosis and mild and virulent 

 pus are constant inliabitants in our mouths, and are found thickest 

 on, in and about the tonsils. Due to the fact that in every swallowing 

 action the toncils are extruded between the flattened pillars of the 

 pharynx, these organs act their function by screening over the crypts 

 the organisms swept by in the food mass and strain the salivary 

 stream of hosts of microbes as cobbles clean a brook." 



