AMEBOID MOVEMENT 



Figure 2. Endoplasmic streaming involved in the formation of a typical 

 food cup. a, the ameba is shown moving toward a live food organism 

 that is resting quietly on the bottom, b, the main pseudopod forks, being 

 the first indication that the feeding process has set in. At c the pseudo- 

 pods have half-way surrounded the prey, but without having come into 

 contact with it. At d the upper sheet of protoplasm, /, (stippled), is 

 flowing dome-like over the prey, while the pseudopods continue to sur- 

 round it. At e the pseudopods have met and fused with each other and 

 the upper sheet of protoplasm has completely covered the space encircled 

 by the pseudopods, and has fused with the pseudopods. g, sheets of proto- 

 plasm which are thrown out along the lower surface under the prey, to 

 form a floor to the food cup. Up to stage e the ameba has not come into 

 physical contact with the prey, but is just about to do so. With the 

 completion of the floor of the food cup, the process of feeding is com- 

 pleted. 



of the ameba when the ameba was carefully stimulated by means 

 of very fine clean glass needles. The conclusion is unavoidable 

 therefore that the shape of the food cup and the method of its 



