Are Entamoeba histolytica and Entamoeba ranarum the same Species? An Experimental Inquiry

Abstract

Nobody who studies the parasitic amoeba of the frog (Entamoeba ranarum) and the dysentery amoeba of man (E. histolytica) can fail to be struck by the remarkable resemblance between these organisms. The development of the former I described for the first time in 1908 and 1909, since when I have had exceptional opportunities of studying the latter; and I can state, with some confidence, that there is no constant structural character which will permit of a distinction being drawn between these two species. The active amoebae can usually be readily distinguished from one another by the inclusions (food bodies) in their protoplasm, but not by their own nuclear and cytoplasmic structure; but the precystic amoebae, devoid of all food bodies, and the cysts, at every stage in their development, are so closely alike that preparations of the one could be used as demonstration specimens of the other.