41 8 WILLIAM A. KEPNER AND WILLIAM H. TALIAFERRO. 



So far as our observations are concerned little can be said about 

 the first condition. The relative number of food vacuoles did 

 not seem to make any marked difference in the conduct of the 

 Amoeba with reference to food. It was not in our power in any 

 way to determine whether the metabolic conditions of the Amceba 

 demanded food or not. 



Our observations are chiefly concerned with the manner in 

 which the Amceba met the conditions of not getting too great an 

 amount of water into the food vacuole and of not letting the 

 prey escape. We can readily understand how by dilution of 

 ferments a relatively large quantity of water in a food vacuole 

 might present a condition to the Amceba in taking in food. The 

 amount of water, therefore, that may enter a food vacuole is one 

 of the dominate factors in controlling the way in which an 

 Amceba reacts to the prey. 



This condition we infer was the primary one determining the 

 action of the Amceba represented in Fig. I. Here the object of 

 prey when first seen lay out away from the surface in a wide 

 angle between two pseudopodia. The stimulus of its contact 

 (not observed by any of us) resulted in the pseudopodia bending 

 their tips towards each other. Had these tips fused the basis of 

 a very large food vacuole would have been formed. No fusion 

 took place here. In the manner described above the one pseudo- 

 podium was wrapped about the Chilomonas until a relatively small 

 space was enclosed over which an ectoplasmic film arched leaving 

 only a small bilobed aperture (Fig. I, e, ap). Out of this small 

 bilobed aperture water was apparently forced, for the enclosure 

 became gradually smaller and after it was reduced to the size 

 of the food vacuole usually encountered the bilobed opening 

 was closed through the convergence and fusion of its lips. After 

 this pore was closed the endoderm also came to lie over the upper 

 side of the food vacuole. In this rather remarkable manner the 

 prey was not allowed to escape and a food vacuole with a relatively 

 small amount of water was formed. 



The reaction of the Amceba represented in Fig. 2 is like that 

 usually described for the conduct of an Amceba with reference to 

 food. Here the amount of water that is to enter the food vacuole 

 is not so great a conditioning factor but the reaction is rather 



