30 PARASITIC AMCEB.E OF MAN. 



i.e., those believing that amoebae are always harmless 

 commensals, more numerous, it is true, in the feces 

 of dysentery patients because of the more favorable 

 environment ; those believing that all amoebae may be 

 pathogenic if suitable conditions be present; and 

 those believing that both harmless and pathogenic 

 species may be present in the intestine of man. 



Prior to Schaudinn's work several investigators 

 had endeavored to establish a classification of these 

 parasites based upon morphological differences, but 

 without success so far as the general acceptance of 

 any one classification. 



In 1893, Quincke and Roos, as the result of their 

 studies, divided the amoebae of man into three species, 

 as follows: 



1. Amoeba intestini vulgaris, 40 microns in 

 diameter, with large granules, which was pathogenic 

 for neither man nor cats. 



2. Amoeba coli mitis, similar in size and appear- 

 ance to the preceding, but which was pathogenic for 

 man alone. 



3. Amoeba coli (Loesch), about 25 microns in 

 diameter, with a finely granular endoplasm, which 

 produced dysentery in both man and cats. 



This classification, which was based largely upon 

 the results of animal experiments, was not conclusive, 

 as from the description of the organisms it was evi- 



