PROTOZOA IN THE DIGESTIVE TRACT 33 



two flagella on each individual; ])ut to see them clearly a 

 dark field illumination is needed. When treated with Lu- 

 gol's solution, the flagella can l)e seen. One flagellum which 

 \ ibrates more actively is directed forward, and about as 

 long as the bod\% while the second flagellum is shorter, 

 but thicker and lies above or in the cytostome. 



2. Stained specimens. The cytoplasm is finely reticulated 

 or alveolated, and contains as a rule bacteria in food vacu- 

 oles (Fig. 7, -^'5). The nucleus is located near the anterior 

 end. It is spherical and shows the central endosome clearly. 

 Very close to the anterior margin of the nucleus, may be 

 seen the insertion points of the two flagella. At one side 

 of the nucleus, there is the cytostome. The ridge surround- 

 ing the mouth is marked by a delicate fibril. Mingled 

 anions numerous uninucleate individuals, binucleate forms 

 with four flagella may be seen. They are dividing indi- 

 viduals. 



Cysts 



1. Living specimens. The cyst (Fig. 7, 6) is a colorless 

 refractile pyriform body. It measures 4.5-7m long by 3-4.5m 

 broad. The contents are granulated and details cannot be 

 made out because of the presence of a comparatively thick 

 cyst wall. 



2. Stained specimens. The cyst (Fig. 7, 7, 8) surrounded 

 by a distinct membrane, appears granulated and contains 

 an ellipsoidal area which is marked bv a looped fibril. The 

 nucleus lies near the center of the cyst. In general appear- 

 ance, the cyst resembles that of Chilomastix mesnili (p. 

 36), but is much smaller than the latter. 



