AMOEBAE OF THE INTESTINAL TRACT. 225 



cytoplasm in which the nucleus is not well differen- 

 tiated. If one watches these young amoebae it will 

 be observed that they soon become motile, a very 

 delicate flagellum appearing at some portion of the 

 periphery; they disengage themselves from the ma- 

 terial in which they often appear to be imbedded, 

 and move about in a rapid, jerky manner, propelled 

 by the flagellum, although at times the latter may 

 appear to draw the organism forward. The very 

 young forms do not stain well with any method 

 which I have tried. 



The flagellate forms grow rapidly and when fully 

 developed measure from 10 to 20 microns in diameter. 

 They are spherical in shape except at that portion of 

 the periphery where the flagellum is attached, where 

 the cytoplasm is continued into the flagellum, thus 

 giving the organism a pear-shaped appearance. The 

 flagellum is from three to four times as long as the 

 diameter of the parasite, and tapers very rapidly, 

 the outer three-fourths being so extremely delicate as 

 to require the most careful focussing to demonstrate 

 it. The nucleus in most instances is situated near 

 the origin of the flagellum, which generally appears 

 to be situated posteriorly. 



The cytoplasm of the parasite at this stage of 

 development is finely granular in structure and con- 

 tains a small, well defined nucleus, and a minute 



15 



