XO.G04J THE CASE OF TRICHOMONAS 



211 



are very small, measuring not more than 0.5 to 1.0 /x, and 

 stain deeply with the chromatin stains. Their function is 

 at the present time only a matter of speculation. Tracing 

 the dorsal membrane posteriorly, it is found to extend to 

 the extreme end of the body, where it narrows and is con- 

 tinued in the form of a terminal flagellum ("Schlepp- 

 geissel") which has a length ordinarily about equal to 

 that of the body. 



From the anterior end of the flagellate extend three 

 more flagella (Fig. 1). These may be even longer than 

 the body of the flagellate itself, and beat downward, as 

 indicated by the arrow in Fig. 1. It frequently appears 

 as if two of these three flagella were united in a common 

 stalk at their base, so that they beat together, while the 

 tliird flagellum beats independently. The origin of these 

 three flagella is difficult to make out, but in many cases 

 they appear to arise from one of the granules of the 

 blepharoplast-complex, and usually not from the granule- 

 which is the origin of the undulatory membrane. 



The only other structures which can be seen well in 

 fresh preparations are the mouth or cjiostome and 

 the food vacuole. The cytostome is a horn-shaped open- 

 ing which extends into the body on the ventral side, and 

 just behind the nucleus (Fig. 2). It may be bordered by 

 cilia. The beat of the anterior flagella is in such a direc- 

 tion that currents of fluid containing the bacteria which 

 serve as the chief food for the flagellates, are driven into 

 the mouth opening. Posterior to the nucleus, usually in 

 about the middle of the cell body lies an oval space, the 

 food vacuole (Fig. 2). It may sometimes be represented 

 by a group of smaller vacuoles which coalesce to form a 

 single cavity. In these vacuoles are usually present bac- 

 teria and cocci undergoing digestion. The structures 

 mentioned above can be seen well in unstained organisms, 

 but there are others which appear to advantage only upon 

 staining. In preparations stained by the Heidenhain 

 iron-hematoxylin method (wet process) the most note- 

 worthy of the remaining structures is the chromatic line. 

 This is a heavily-staining band which extends like the arc 



