110 PROTOZOAN PARASITISM 



are irregularly distributed chromatin granules on 

 the rim and a central or near-central karyosome. 



For the finer details of morphology the reader is 

 referred to Kofoid and Swezy (1924). 



The existence of cysts has not been conclusively 

 shown. It is not unlikely that the conditions of its 

 environment, in which there is no comparable regular 

 change and inspissation of its medium, such as is 

 associated with intestinal amoebae and related to 

 their encystment, and, also, the literally direct ready 

 transmission from one host to another, have made it 

 unnecessary that this protozoon should have such a 

 resistant protection. If it ever encysts it must be 

 under rare and unknown conditions. 



HABITAT AND EFFECT 



Endamoeha gingivaUs is practically a universal 

 inhabitant of the mouth of man at some time during 

 an average lifetime. All people who have any degree 

 of pyorrhoea alveolaris harbor it, and most people past 

 early adult life have some grade of this condition. 



It ma}^ be found in the crypts of the tonsils, in 

 ulcers of buccal mucosa or the tongue. Generally 

 speaking it does not occur in the normal mouth but 

 it may and commonly does occur whenever there is 

 a recess or pocket in which it may grow and accumu- 

 late. The writer (1915) recorded findhig it on the 

 false teeth and between them and the gum of two 

 persons who were completely toothless, with healed 



