36 



S. O. MAST AND F. M. ROOT 



The process of digestion continues very slowly. Isolated 

 amebae have been seen to retain vacuoles containing rotifers for 

 three days and then the process was not complete. On Noveni- 



A 



B 



o.3mm 



Fig. 2 Camera sketches showing an ameba feeding on a rotifer: r, rotifier; 

 y, young rotifer attached to the mother; c, contractile vacuole; mm, projected 

 scale. 



A Ameba and rotifer as they appeared when discovered. They had evidently 

 been united for a considerable time for the foot of the rotifer was partially di- 

 gested. November 30, 2 p.m. 



B Same ameba and rotifer, December 1, 9 a.m. The old rotifer was dead 

 but the young one was still alive. 



C and D Same rotifer and ameba, also a second ameba, December 1, 12..28 

 and 1.08 p.m. respectively. At 12.28 the second ameba was rapidly flowing 

 around the rotifier from below; at 1.08 the rotifer was nearly covered, the original, 

 ameba being attached to the posterior and the other to the anterior end. At 

 2.55 p.m. the second ameba had left the rotifier and the other one was rapidly 

 flowing away. Shortly after this the young rotifier broke through the cuticula 

 of the mother and escaped apparently uninjured. The mother was dead, the 

 cuticula was badly crumpled, and the foot was nearly gone. Note that the roti- 

 fer has decreased much in size. 



E An ameba containing a rotifer which had just been swallowed. The roti- 

 fer was still alive when the sketch was made, although the foot was much in- 

 jured. The ameba covered only about half of the rotifer when it was found. A 

 little later the pseudopods began to extend rapidly and in a very short time the 

 rotifer was entirely surrounded. 



