SENSITIVENESS OF AMCEBA 71 



solved oxygen in the water, the pseudopodia are with- 

 drawn and the animal becomes spherical and motion- 

 less. Amoeba is also sensitive to the presence of food, 

 for it does not normally ingest objects which it cannot 

 digest, and this probably means that chemical substances 



FIG. 3. A, ingestion and coiling up of a thread of Oscillaria (an 

 alga) by Amoeba verrucosa. B, ingestion and coiling up of a 

 thread of shellac by a drop of chloroform. After Rhumbler. 



> 



diffusing out from the organisms which form its prey 

 come into contact with the ectoplasm of the amoeba, 

 and this stimulus leads to the envelopment of the 

 prey. 



Reproduction of Amoeba. When the growth of the 

 individual amoeba has reached a certain limit the animal 



