REACTIONS OF AMCEBA PROTEUS TO FOOD. 417 



be no rejection of food when it presented itself in a manner 

 favorable for acceptance. Nor does it follow that when an 

 Amoeba has rejected food that this rejection is final. On Sep- 

 tember 26, Mr. L. Grady Burton saw an Amoeba proteits which 

 was flowing along the line of a large pseudopodium come in 

 contact with a quiet Chilomonas paramoecium. The Amoeba 

 proteus twice touched the Chilomonas and each time withdrew 

 its pseudopodium. The Amoeba proteus then moved around and 

 by the Chilomonas. It now lay opposite a side which was at 

 right angles to the one first encountered. The Amoeba then sent 

 out a pseudopodium at right angles to the first one and again 

 touched the Chilomonas. It rejected the flagellate again but 

 on touching it the second time in this new position the Amoeba 

 proteus ingested the Chilomonas. 



These reactions too show a departure from the description 

 given by Jennings ('06). "The essential features of the food 

 reaction seem to be the movement of the Amoeba toward the 

 food body (long continued, in some cases), the hollowing out of 

 the anterior end of the Amoeba, the sending forth of pseudopodia 

 on each side of and above the food, and the fusion of the free 

 ends of the pseudopodia thus enclosing the food, with a quantity 

 of water. The reaction is thus complex; at times, as we have 

 seen, extremely so." 



As we have been able to observe the reactions of the Amoeba 

 proteus are not always "the hollowing out of the anterior end of 

 the Amoeba, the sending forth of pseudopodia on each side of 

 and above the food, and the fusion of the free ends of the pseud- 

 podia" ; but the reaction is a variable one and may arise from the 

 side of the Amoeba's body and involve primarily but a single 

 pseudopodium. 



Moreover the reaction of an Amoeba proteus to food is in each 

 case determined by the conditions presented at the time of 

 contact. Some of these conditions are: 



1. The metabolic condition of the Amoeba proteus, demanding 

 or not demanding food. 



2. The form of the Amoeba's body at the time the food is pre- 

 sented to it with reference to (a) the amount of water that may 

 enter a food vacuole, and (6) the possible retreat of the object of 

 prey. 



