OF THE ALIMENTARY TRACT 111 



gums and alveolar processes. In ulcers of buccal 

 mucosa and tongue, where it was observed (Lynch, 

 1915), its appearance and disappearance seemed to 

 bear no relation to the development or progress of the 

 pathological state. It was evidently a secondary 

 invader there. 



The amoebae may be found in any grade of in- 

 flammation of the gums, from that grossly incon- 

 spicuous but showing a tendency of the gingiva to 

 bleed unduly and microscopic pus behind the margins, 

 to the chronic suppurative inflammation wath pus 

 pocket formation and receding of the gum margins, 

 known as pyorrhoea alveolaris, in all of its stages of 

 advancement. It occurs where there is exudation 

 from inflamed tissue and a harbor for its lodgment. 



In the depths of the pus pockets it flourishes, 

 as was shown by the writer ( 1915) , by Bass and Johns 

 (1915), and more recently by Kofoid and Hinshaw 

 (1929), who, according to Kofoid (1929), studied the 

 amoeba in relation to its w^hole environment by sec- 

 tion of the pus pocket and surrounding structures in 

 toto. According to these investigators the amoebae 

 occur about the filamentous border of leptothrix and 

 other similar bacteria which have undergone calcifica- 

 tion to form the tartar. Here they feed on the nuclei 

 of the disintegrating pus cells. They are very nu- 

 merous and form a heavy layer in the outer free fila- 

 mentous covering of the solid serumal tartar, being 

 most abundant about the point in the deeper part of 

 the pocket where the tartar is thickest, and extending 



