208 PARASITIC AMOEBA OF MAN. 



spinose. A distinct difference exists in the appear- 

 ance of the ecto- and endoplasm, while it reproduces 

 by simple division, schizogony, and by spore forma- 

 tion within a cyst. 



Size. Koidzumi gives the average size of this 

 amoeba as 25 microns in its longest diameter, but 

 it varies from 20 to 30 microns in length and 15 to 

 20 microns in breadth. It seldom measures over 

 40 microns in its longest diameter. There is nothing 

 characteristic about the size of this organism, except 

 that it is longer in one diameter than in the other. 



Shape. When motionless Entamceba wpponica 

 is always oval in shape, according to Koidzumi, which 

 differentiates it from the other species of amoebae 

 which have been described, all of which are spherical 

 in shape when motionless. Numerous changes occur 

 in the shape of the organism during motility due to 

 the extrusion of pseudopodia. 



The Cytoplasm. The cytoplasm of this species 

 much resembles that of Entamceba tetragena, being 

 divided into a well marked ecto- and endoplasm. 

 The ectoplasm, however, forms but a very small 

 proportion of the cytoplasm, existing as a narrow 

 rim surrounding the endoplasm. When moving the 

 ectoplasm appears larger in amount because it is 

 concentrated in the pseudopodia. It is clear, color- 

 less and very refractive. The endoplasm, comprising 



