FOOD-REACTIONS OF PELOMYXA 389 



each part entering a food-vacuole. The result was there were 

 seven food-vacuoles in the posterior end of the paramaecium 

 by the time it had lost the spheroidal shape it had assumed in 

 the later stages of overcoming the ciliates. 



October 26, 1916. The specimen concerned with this ob- 

 servation had been starved for four or five days in a hanging 

 drop of water. Paramaecia were added to its drop of water at 

 2.05 p.m. These many paramaecia, striking it on all sides at 

 frequent intervals, caused it to respond at the points of contact 

 by throwing out frequent short projections. Within five 

 minutes, however, a paramaecium entered a bay between three 

 pseudopods, two of which lay within the plane of the par- 

 amaecium' s axis and the third one lay beneath the par- 

 amaecium. The paramaecium backed in and out of the bay at 

 first; but as it became quieter, pseudopods a and a', figure 8, 

 were formed. Then a and a' widened to contour b and b' . 

 In the meantime an over-arching film of protoplasm arose, 

 its advance being indicated by contours 1 and 2. After this 

 over-arching had been completed contours b and b' advanced 

 to c and c' '. We could not see what modification of the lower 

 pseudopod took place. Eventually, however, the paramaecium 

 was enclosed within a vacuole so small that the ciliate being 

 bent upon itself formed a spheroidal mass. The living par- 

 amaecium, within its intimately fitting gastric vacuole was 

 delivered to the 'posterior' end of Pelomyxa's body. An in- 

 teresting departure from the usual method of dealing with 

 paramaecium was encountered in this case. Usually the par- 

 amaecium is killed as indicated by its change of form or by its 

 fragmentation within fifteen minutes. This animal was en- 

 closed within a rounded, intimately fitting gastric vacuole at 

 2.30 p.m. or earlier and within this it continued to spin peri- 

 odically until 4.43 p.m. at which time its own contractile 

 vacuoles were vigorously pulsating. We hope to make this 

 type of variability the subject of another study. 



The following observation indicated the manner in which 

 the contingencies of the situation are met when the motile ob- 

 ject of prey lies above the plane in which Pelomyxa is traveling. 



