196 



THE BEHAVIOR OF LOWER ORGANISMS. 



given a very interesting account of the rolling up and ingestion of threads 

 of Oscillaria by this species (see p. 223).* 



PURSUIT OF FOOD. 



Amo&ba proteus does not always succeed in ingesting its food so 

 easily as in the case just described (p. 194). There is, as noted above, 

 a tendency for the food body to be pushed away by the forward move- 

 ment at the anterior end of 'the Amoeba, and this sometimes gives 

 serious difficulty. In such cases Amoeba may show what would be 

 called in higher organisms remarkable pertinacity in continuing its 



FIG. 73. f 



attempts to ingest the food. This will be illustrated from a concrete 

 case (Fig. 73). 



An Amoeba proteus was creeping toward an encysted Euglena. 

 The latter was perfectly spherical and very easily moved, so that when 

 the anterior edge of the Amoeba came in contact with it the cyst merely 

 moved forward a little and slipped to one side (the left) . The Amoeba 



*Leidy (1879, P- 86) gives a very similar account of the ingestion of filaments 

 of algae in Dinamceba. 



fFiG. 73. Amoeba following a rolling Euglena cyst. Nos. 1-9 show successive 

 positions occupied by Amoeba and cyst. See text for explanation. 



