﻿IX, B, 1 WUlets: Intestinal Parasitism 89 



The difference in size of the cysts of the two species is very 

 helpful in making a differential diagnosis. Size alone, however, 

 is not dependable for the reason that small E. coli cysts are 

 found at times. Large 4-nucleated cysts have not been seen 

 by me unless encystment was obviously incomplete. Since the 

 nuclei lie in different plains, doubt occasionally exists as to the 

 number of nuclei present in a given cyst. By using gentle 

 pressure on the cover glass, the cyst wall can be broken and the 

 escaped nuclei, lying just outside of the cyst wall, counted. 

 Another practical point in differentiating entamcebic cysts is 

 the manner in which a preparation is made for examination. 

 It is my custom to make a thin preparation and to draw off the 

 excess water with a piece of filter paper so that the cover glass 

 fits snugly to the specimen. Thus the cysts are flattened out 

 somewhat and the counting of the nuclei facilitated. This man- 

 ner of making a cover-slip preparation also lessens the proba- 

 bility of the cyst shifting to another field when the oil immersion 

 lens, which must always be used to make a reliable differential 

 diagnosis, is applied. 



Using Walker's findings as a basis, a differential diagnosis 

 was made upon cysts found in 76 cases. Completely encysted 

 forms with 4 nuclei were called E. histolytica, and those with 

 8 or more nuclei were called E. coli. The results obtained are 

 given in Table IV. 



Table IV. — Differential diagnoses rendered upon encysted forms of 



entamoeba in 76 cases. 



Species. 



Number. 



Per cent. 



Entamoeba eoli and E. hUtolytica present _ 



46 



27 



4 



72 



■ 49 



69.2 

 36.6 

 6.8 

 94.7 

 64.6 



Entamoeba eoH only present 



Entamceba histolytica only present 



Entamoeba eoli preeent 



Entamceba histolytica present. . ., 





In making the differentials, 4 cover-glass preparations were 

 examined before a specimen was said to be negative for either 

 E. coli or E. histolytica if cysts were plentiful; 10 cover-glass 

 preparations, if cysts were scarce. In some instances a second 

 specimen was examined because doubtful forms were en- 

 countered in the first one. In the vast majority of the cases 

 presenting a double infection, E. coli cysts greatly outnumbered 

 E. histolytica cysts. 



Data with which the foregoing results would naturally be 



