DIFFERENTIATION OF AMCEBAE 



257 



staining I prefer to alum haematoxylin. It was formerly customary 

 to recommend the administration of salts prior to examining for 

 amoebae. 



Walker warns that such a procedure gives us amoebae which are difficult to differ- 

 entiate, the nuclear characteristics of E. coli and the tetragena nucleus of E. histo- 

 lytica being much alike as they both contain much chromatin. In a dysenteric 

 stool the histolytica type of nucleus, containing but little chromatin, does not 

 resemble the nucleus of E. coli. 



He prefers the examination of formed stools obtained without a 

 purgative. 



Walker also notes the advantages of examining a specimen with a %-inch ob- 

 jective as encysted amoebae are easily picked up. In opposition to the usual recom- 

 mendation of text-books to report only on motile amcebae, he recommends the 

 making of a differential diagnosis on nonmotile encysted forms. This however is 

 now generally accepted by experienced workers as true. The four nuclei cysts of 

 E. histolytica are from n to 14 microns in diameter while the eight nuclei ones of E. 

 coli are from 1 6 to 25 microns in diameter. 



Sellards and Baetjer note that inoculation of kittens per rectum or 

 by feeding dysenteric stools rich in amcebae has resulted in infection 

 in about 50% of experiments. 



By inoculating the material directly into the caecum they were 

 able to infect every one of their kittens. They were also able to 

 propagate a strain of amcebae through a series of animals for several 

 months. 



The intracaecal inoculations yielded positive results in diagnosis of 

 human amcebiasis when the clinical manifestations were obscure 

 and the amcebae in the discharges so few and atypical as to make such 

 an examination unsatisfactory. 



As differentiating the two entamcebae Walker gives the following table: 



MOTILE STAGE 

 A. Entamceba histolvtica 



B. Entamceba coli 



1. Appearance hyaline. 



2. Refractiveness more feeble. 



3. Movements active in the fresh stool. 



4. Nucleus more or less indistinct. 



5. Chromatin of nucleus scanty. 



17 



1. Appearance porcelaneous. 



2. Refractiveness more pronounced. 



3. Movements sluggish. 



4. Nucleus distinct. 



5. Chromatin of nucleus abundant. 



