546 ASA A. SCHAEFFER 



are considered. The relation between the size of the food cup 

 and that of the object is greatly influenced by the condition of 

 the anieba, such as hunger, rate of reaction, etc. The higher the 

 rate of reaction and the greater the hunger, the larger, within 

 limits, will be the food cups. 



Number of food cups 



In the granular type usually only one food cup is observed at a 

 time but occasionally, when food is plentiful, two or even three 

 may be started at exactly the same time. Whenever a food cup 

 is formed the whole ameba is apparently affected even though 

 the food cup is only a small one, for the main stream of proto- 

 plasm is interrupted for a longer or a shorter time. 



The number of food cups which a raptorial ameba may form 

 is apparently limited only by the amount of protoplasm. Three 

 may be formed side by side simultaneously or nearly so. Three 

 or four are frequently observed starting at the same time. Some- 

 times two or more cups coalesce forming a larger one in which the 

 stimulating object or objects are finally ingested. The success 

 or failure of a food cup has no influence on the formation of 

 new cups either in the same vicinity or elsewhere, if the ameba is 

 hungry. 



Modifications in the formation of food cups 



The range of variation in the shape, size, and mode of forma- 

 tion, of food cups is very great. Indeed it can almost be said 

 that no two are alike in all respects. When it is remembered 

 that among other factors the character of the food object, the 

 condition of hunger, the rate of reaction, the distance between the 

 object and the ameba, the part of the ameba stimulated, the 

 movement of the food object, and the previous experience of the 

 ameba, have each their efTect in modifying food cup formation, 

 it is evident that the same constellation of conditions seldom 

 occurs twice. The process is therefore not a stereotyped one, 

 but is adjustable to meet varjdng conditions. 



