.544 ASA A. SCHAEFFER 



the food object; upon its nearness to the ameba; upon what part 

 of the ameba — posterior or anterior — ^is near the object; upon 

 the 'condition' of the ameba, that is, its state of hunger, its just 

 previous feeding experiences, etc. As described by several ob- 

 servers, two pseudopods are sometimes sent out toward the food 

 object, one on either side, and not touching it. As these encircle 

 the food, a thin sheet of protoplasm arising from the base and 

 dorsal sides of the pseudopods, is thrown out over the object. 

 The pseudopods and the sheet of protoplasm then fuse all around, 

 forming an inverted cup of protoplasm over the surface of the 

 glass dish or slide, with the food object in the centre. A food 

 cup is frequently formed in this manner over an active organism 

 such as a urocentrum, Paramecium, coleps, chilomonas, etc., if 

 such an organism lies fifty microns or less from the ameba. 



The two encircling pseudopods are sometimes omitted and only 

 a broad thin sheet thrown out over the prey, forming finally a 

 cup of the same appearance as when the encircling pseudopods 

 are also present. Food cups of this character may be foniied at 

 any part of the ameba. Such a food cup may involve the whole 

 ameba, or only the tip of a small pseudopod. In the latter case 

 the main stream of protoplasm is not affected visibly, and the 

 cup may be regarded therefore as a side issue. In nearly all 

 cases the food cups are foraied at the anterior part of the ameba 

 for the simple reason that edible prey is encountered here first. 

 Both raptorial and granular amebas form food cups of this kind. 



Food cups formed in this way may be of enonnous size among 

 the raptorial amebas, if the stimulating object is large, and a 

 number of pseudopods — as many as five or more — may coalesce 

 to fomi a thin sheet which is sent out over the object. 



Food cups formed in any of these ways are usually bounded 

 on the under side by the glass bottom of the object holder. 

 When this is the case the ectoplasm of the rim of the cup adheres 

 to the glass firmly. The captured organism becomes more or 

 less inactive while the glass is still bounding the food vacuole, as 

 may be shown by breaking the ameba loose sometime after the 

 food cup is formed. This might indicate that digestive sub- 



