PROTOZOA IN THE DIGESTIVE TRACT 19 



less abnormal, and are insignificantly small in number as 

 compared with tlie normal mature eight-nucleated cysts 

 in routine work. The glycogen body appears to disappear 

 before the cvst is mature, and may be entirely lacking even 

 in vountT cvsts. 



3. Entamoeba gingivalis (Gros 1849) 



Synonym: Endamoeba gingivalis (Gros) 



This is the amoeba of human mouth. It lives in carious 

 teeth, in tartar and debris accumulated around the roots of 

 teeth, and in abscesses of gum, tonsils, etc. Although held 

 by some as the cause of pyorrhoea alveolaris, exact evi- 

 dence for its pathogenicity is still lacking. It has been 

 found in healthy gum and in false teeth, and is generally 

 looked upon as a commensal. Only the trophic stage is 

 known, cysts not having been observed up to the present 

 time. It is of common occurrence. 



Trophozoites 



1. Living specimens. As seen in fresh material in saliva 

 under a sealed cover glass the amoeba (Fig. 3, i- 2) is 

 as active as E. histolytica (p. 9). The cytoplasm is well 

 differentiated. In some a broad single pseudopodium is 

 formed at one end, which results in progressive movement, 

 similar to the monopodal forms of E. histolytica or free- 

 living limax amoebae; in others several pseudopodia com- 

 posed chiefly of the ectoplasm are formed in quick suc- 

 cession (Fig. 3, 1). The endoplasm is often vacuolated 

 and contains a large number of food particles and a 

 nucleus which is frequently seen as a ring about 3-4m 

 in diameter. The food particles are almost always charac- 



