EXPERIMENTAL AMCEBIASIS IN KITTENS 195 



amoebae were pathogenic to kittens and that the assoaiated bacteria 

 were not. Another cause of disagreement was that differentiation 

 had not been made between pathogenic and non-pathogenic amoebae, 

 of which both kinds were found in human stools. Schaudinn 

 (1903), Craig (1905), Mereck (1907) and others demonstrated 

 that only Endamocha Jiisfolytica which was known to be pathogenic 

 in man was also pathogenic in kittens. Other investigators have 

 attempted to attenuate or increase the virulence of E. histolytica 

 by continued passage through kittens (Wenyon, 191 2, Dale and 

 Dobell, 1917). Kittens have also been used in attempts to differ- 

 entiate between the extremely pathogenic and less pathogenic 

 strains of this Endamocha (Wagner and Thompson, 1924, Brumpt, 

 1925, Kessel, 1927). Sellards and Theiler (1924) demonstrated 

 that infection of kittens by ligating the colon and injecting the 

 parasites through its wall was practicable and that excystation 

 occurred when this method was used. Sanders (1928) found that 

 kittens injected with a virulent strain of E. histolytica showed a 

 slight anemia, a loss in weight and a polymorphonuclear leu- 

 cocytosis plus a rise in the numbers of large mononuclear cells 

 eventuating in the death of the animal. Terminal bacteremias 

 were occasionally met with in these injections. The writer (1929) 

 began a series of experiments to determine how the amoebae pro- 

 duced lesions. In this work it appeared that diarrhea preceded 

 dysentery, due to the multiplication of the amoebae within the 

 lumen of the colon and the response of the host to a hypothetical 

 toxic substance which was apparently excreted by the parasites. 

 The character of fresh lesions suggested that the amoebae were also 

 able to invade tissues and to cause bleeding. The ulcers appeared 

 to commence in the surface epithelial cells and are, therefore, not 

 preceded by abscesses as would result if the amoebae first invaded 

 the crypts, causing them to become occluded and necrotic. It was 

 also demonstrated that the effects of the reaction of the host on 

 the amoebae may be studied morphologically. The nuclei of the latter 

 underwent pathological changes similar to those which occurred 

 in the injured cells of the body. Though, as Kartulis demonstrated, 

 the bacteria do not act in a primary capacity, they appeared to 

 work with the amoebae as soon as the initial lesions had com- 

 menced. The frequent occurrence of bacillary diarrhea and dysen- 

 tery in the controls was one of a number of complicating factors. 

 Conclusive evidence on most of the problems outlined above has 



