AMEBA 



47 



tion as follows. The Ameba flows against the food particle, 

 which does not adhere but tends to be pushed forward away 

 from the animal (Fig. 14, i). That part of the body directly 

 back of the food ceases its forward movements while, on either 

 side and above, pseudopodia are extended which gradually form 

 a concavity in which the food lies (Fig. 14, 2) and finally bend 

 around the particle (Fig. 14, j) until their ends meet and fuse 



^j&f>.oj%y ^* t 3g!g& 



FIG. 14. Amcba ingesting a Euglena cyst, i, 2, 3, 4, successive stages in the 

 process. (From Jennings.) 



(Fig. 14, 4). A small amount of water is taken in with the food, 

 so that there is formed a vacuole whose sides were formerly the 

 outside of the body, and whose contents consist of a particle of 

 nutritive material suspended in water. The whole process of 

 food-taking occupies one or more minutes, depending on the 

 character of the food. Ameba is not always successful in ac- 

 complishing what it undertakes, but when it does not capture its 

 prey at once, it seems to show a persistence usually only attributed 

 to higher organisms. No doubt the reactions in food-taking 

 depend upon both mechanical and chemical stimuli (39). 



Imitations of the engulfing of food by Ameba have been de- 

 vised, based on the theory that ingestion depends on the physical 

 adhesion between the liquid protoplasm and the solid food. 

 Drops of water, glycerin, white of egg, etc., will draw into con- 



