310 WM. A. KEPNER AND FRANK HELVESTINE, JR. 



in a hanging drop of water, will show that the mouth is provided 

 with a flattened, circular lip which has many fine radiating lines 

 upon or in it, thus presenting the appearance of a sucking disc 

 (fig. 1, D). 



Certain observations have been made upon the functions of 

 the pharynx with its disc-like mouth. The pharynx functions in 

 a twofold manner, a) as a prehensile and, b) as a secreting organ. 

 Martin ('08, p. 268) says that when Microstoma attacks Hydra 

 "it fixes itself for a short time by its posterior end in the neigh- 

 borhood of the Hydra, and everts its pharynx to its full extent." 

 He then refers to his figure 10 to illustrate a pharynx fully ex- 

 tended (text figure). This figure does not show adequately the 



Text-figure Ventral aspect of anterior end of Microstoma to show mouth dis- 

 tended. From Martin ('08). 



degree to which the pharynx of Microstoma may be distended. 

 We starved ^a specimen for five days and then presented it with 

 half of an oligochaete worm. The worm was at once attacked 

 near its middle, the Microstoma's pharynx was distended in such 

 fashion that the body assumed the contour of a laterally com- 

 pressed funnel or cone. As the mouth of the rhabdocoele was 

 thus distended, the prey, though wriggling much at its extrem- 

 ities, was sucked into the lumen of the enteron (fig. 2). After 

 the prey had been drawn down to assume a U-shape, it was next 

 handled in such manner as that one arm of the U was gliding 

 from the mouth of Microstoma as the other was being dragged 

 into it as indicated by arrows in figure 3. \Mien the ingested 



