642 



AMCEBTC DYSENTEEY 



pathogenic properties. The entamoeba described by Hartmann 

 under the name E. africana is generally recognised as being 

 the same organism. Further research has resulted in its being 

 generally recognised that E. histolytica and E. tetragena are the 

 same, or rather that there is one organism of dysentery, for which 

 Schaudinn's name of E. histolytica has been retained, though 

 its process of encystment corresponds with that originally 

 described in the case of E. tetragena. Moreover, a small 

 entamoeba, described by Elmassian E. minuta, is also now 

 considered to represent merely a stage in the life-history of 

 E. histolytica. 



Entamoeba histolytica, as seen in the stools of acute dysentery, 



a. b 



Fig. 187. — Entamoebas of dysentery. 



a and b, amoebse as seen in the fresh stools, showing blunt amoeboid 

 processes of ectoplasm. The endoplasin of a shows a nucleus, three red 

 corpuscles, and numerous vacuoles ; that of b, numerous red corpuscleB 

 and a few vacuoles. 



c, an amoeba as seen in a fixed film preparation, showing a small rounded 

 nucleus (Kruse and Pasquale). x 600. 



occurs in the form of rounded, oval, or pear-shaped cells, measur- 

 ing 15-50 //., usually about 30 p, in diameter (Figs. 187-194, and 

 Plate VI., Fig. 23). Considerable variations in size are, however, 

 met with. When at rest, a somewhat clear, highly retractile ecto- 

 plasm and a granular or vacuolated endoplasm may sometimes 

 be distinguished, though this is not always the case. The 

 nucleus is rounded or oval, and is seen with difficulty ; its 

 position is usually excentric, and is sometimes quite at the 

 margin of the endoplasm. In stained specimens it is seen to be 

 poor in chromatin, which is arranged under the nuclear mem- 

 brane, the latter being ill defined. The pseudopodia, which are 

 quickly protruded and retracted, are blunt aaid appear to be of a 

 tough consistence, a property which Schaudinn considered of 



