KI. ACTIONS OF AMCEBA PROTEUS TO FOOD. 413 



The food-reaction of Amceba involves movement. It is how- 

 ever, a more complex phenomenon than mere movement. "The 

 capture and ingestion of food, in its simplest form, occurs in the 

 group of Rhizopoda, where, as in Amceba proteus, any part of the 

 body can act as a mouth. In this form pseudopodia are pushed 

 out toward the victim (a flagellate, ciliate, minute plant form of 

 any kind, or even a higher animal, such as a rotifer or worm) and 

 entirely surround it, together with a certain amount of water, 

 thus forming a gastric vacuole, or an improvised 'stomach' 

 (Calkins '01). This description gives the details as generally 

 given for the ingestion of food. 



So far as we have been able to determine no departure from 

 this simple method of capturing food by an Amoeba proteus has 

 been described. Jennings observed an Amceba persistently push 

 a spheroidal Euglena cyst from place to place in an effort to 

 ingest it. He also observed an Amceba proteus ingest repeatedly 

 a smaller specimen of Amceba proteus, the latter each time 

 breaking through the protoplasmic wall of its captor. But even 

 in these most interesting instances the prey was taken into the 

 body by the ingesting protoplasm flowing about each side of the 

 prey with equal velocity. On September 25, Mr. F. L. Kline, 

 Mr. W. A. Williams, Mr. J. P. Williams and Mr. R. T. Scott 

 called the attention of one of us to an Amceba proteus that was 

 sending a pseudopodium out from the side of its body posteriorly 

 in such a way as to surround a quiet Chilomonas paramcecium. 

 In this case it was remarkable that the entrapping protoplasm 

 was flowing about but one side of the prey, the side of the 

 Amceba 1 s body furnishing one w r all of the forming food vacuole. 

 Later Mr. Scott observed that the food vacuole was completed 

 through the fusion of the end of the pseudopodium and the side 

 of the body (text-figure i). September 26, Mr. E. M. Baker 

 called our attention to an Amceba proteus tha.t had a Chilomonas 

 paramcecium lying between two pseudopodia as indicated in 

 Fig. i, a. He had not observed where the contact with the prey 

 had been made, but it was evident that the two pseudopodia were 

 closing up behind the Chilomonas paramcecium. We then called 

 the attention of Mr. C. A. Amos, Mr. H. H. Buehler, and Mr. 

 A. H. Brewster to the specimen. As we took turns with these 



