SARCODINA 



729 



the slide under the microscope shows the structure of the nucleus ; the 

 examination is made in water under a cover glass. 



7. When the differentiation is complete the slide is washed in dis- 

 tilled water and passed through graded alcohols, 80, 95 and absolute 

 into xylol and xylol-balsstm. This stain is permanent. 



Romanowski stains on dried smears may be used, but are not so 

 good. 



In fresh specimens Endameba histolytica presents the following* 

 appearance : the vegetative forms are pale, unstained with bile, and 

 are seen to be large bodies, 20 to 30 microns in diameter, consisting of 

 endo- and ectoplasm, and often showing a delicate nucleus and also 



FIG. 158. ENDAMEBA HISTOLYTICA. (Army Medical School Collection, 

 Washington, D. C.) 



many inclusions in the digestive vacuoles, principally red blood cells. 

 The organisms for several hours after the stool is passed remain ac- 

 tively motile, pushing out clear, glass-like pseudopods, into which the 

 granular endoplasm pours as the ameba progresses across the field. 

 Even when there is no progression the pseudopods are protruded or 

 retracted first in one then in another direction. There is always, dur- 

 ing motion, a distinct separation of the clear ectoplasm from the 

 granular endoplasm, and the latter, in acute cases especially, contains 

 many red blood cells, occasional examples showing as many as twenty 

 or thirty. The presence of red blood cells either entire or partly di- 

 gested is characteristic of Endameba histolytica, since they are pres- 

 ent in Endameba coli in only rare instances. The ameba is sometimes 

 greenish, and it is supposed that this color is due to hemaglobin 

 liberated from the ingested red cells. The pseudopods of this species 



