ECOLOGY, COMMENSALISM AND PARASITISM 389 



the "Fresh Water Rhizopods of North America," discovered a 

 parasitic ameba in the intestine of Blatta orientalis, which he first 

 named Amoeba blattae. Recognizing the impropriety of grouping 

 the relatively huge fresh water and free-living amebae, such as 

 A. proteus and the minute intestinal ameba of the cockroach in 

 the same genus, he changed the generic name of Amoeba blattae to 

 Endamoeba blattae. Sixteen years later Casagrandi and Barbagallo 

 (1895) studied an ameba from man which, apparently in ignorance 

 of Leidy's work, they named Entamoeba coll, changing it two years 

 later to Entamoeba hominis. Now in my opinion this is the exact 

 equivalent of Leidy's Endameba, for in this country we use the 

 form "endo" (witness endoplasm, endoderm, endothelium, etc.) in 

 the same sense that Europeans use the form "ento" (entoplasm, 

 entoderm, etc.). Endameba and Entameba thus are the same, the 

 form depending on the custom of the country where used, and there 

 is little justification for employing them, as Dobell, followed by 

 Wenyon, suggested, to represent two distinct genera. If there is a 

 generic difference between the intestinal amebae of the cockroach 

 and that of man, which is by no means established, then some at 

 least of the human forms should be included under Chatton and 

 Lalung-Bonnaire's name, Loschia (1912). 



2. Early Etiological Observations. —This period marking the begin- 

 ning of a long controversy over the pathogenicity of intestinal 

 ameba may be arbitrarily fixed between the approximate dates 

 1880 and 1902. Leidy's generic name was little used until the late 

 '90's; indeed not until after Casagrandi and Barbagallo had intro- 

 duced the form Entameba. At the beginning of this period it was 

 generally believed that the human intestinal forms belong to one 

 species which, following Losch, was known as A. coli. The con- 

 troversy then was over the question whether or not A. coli is patho- 

 genic, and the cause of dysentery. Grassi (1879, 1882, 1883, 1888) 

 found amebae widely distributed in feces of normal individuals 

 as well as in those suffering from diarrhea, and when cysts of the 

 organism are swallowed by humans they give rise to amebae which 

 multiply in the intestine but cause no symptoms of dysentery or 

 other intestinal upset (1888). He was emphatic in concluding that 

 the ameba with which he worked and which he regarded, erro- 

 neously, as the same as Losch 's "A. coli," is altogether harmless 

 to man. The seed thus planted by Losch developed into a healthy 

 weed with Grassi, became a permanent plant with Schaudinn (1903) 

 and has never been uprooted. Entamoeba coli as a harmless parasite 

 had come to stay. 



The pathogenic importance of the so-called A. coli was also well 

 supported at this early period. Losch started it and was supported 

 in the 'SO's by KartuHs in Egypt (1885, 1886, 1887, 1891), by Koch 

 (1883), Koch and Gaffky (1887) and others. Sections of intestinal 



