IMMUNITY REACTIONS WITH AMOEBAE. 



By Andrew Watson Sellabds. 

 {From the biological Laboratory, Bureau of Science, Manila, P. I.) 



The aetiology and also the diagnosis of amoebic dysentery involve the 

 question of whether non-pathogenic as well as pathogenic amoebae may 

 be encountered in the human intestine. In the development of the evid- 

 ence bearing upon this question, two factors have arisen which are of 

 especial interest. In the iirst place important morphological differences 

 have been described for amcebae from various sources, and secondly cul- 

 tures of amcebse have been obtained from dysenteric stools. It is main- 

 tained^ that definite morphological distinctions occur in the amcebae found 

 in the intestine with differences in clinical manifestations corresponding 

 to the type of amoeba which is present. Thus, one of these types may 

 persist over long periods of time without the production of definite symp- 

 toms. This fact appears to constitute the principal evidence in support 

 of the existence of a non-pathogenic species of amoeba in the intestine. 

 However, the morphological differences between this type of amoeba and 

 that occurring in active dysentery have not been accepted by certain 

 observers, and the existence of this type as a distinct species has been 

 questioned. 



In regard to the cultivation of amoebae,, there is some uncertainty 

 concerning the exact significance of the cultures which have been obtained 

 from dysenteric stools. Some investigators consider that the amcebae in 

 these cultures are pathogenic. Others regard them as purely saprozoic 

 forms, which are only accidentally present in the faeces, maintaining that 

 the morphological differences are sufficient to distinguish them absolutely 

 from the amcebas ordinarily seen in a dysenteric stool. 



In the present paper an attempt has been made to distinguish amcebae 

 by their biologic properties without especial reference to morphology. 

 Immunization of animals has been carried out with various strains of 

 amoebae with the expectation of producing immune bodies for the com- 

 parison of the various strains. It was intended, in the first place, to 

 determine whether any differences could be detected in the immunity 

 reactions of cultures of amoebae obtained from parasitic as compared with 

 those from saprophytic sources. In the second place, the sera of dyseur 



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