AMCEBA 



"5 



to be rich in fatty substances. Artificial foams can even 

 be induced to carry out movements which in their general 

 features resemble contraction. It should be noted, how- 

 ever, that the special features of the contraction of Amoeba 

 are not found in them. 



Amosba feeds on small organisms, which it ingests by 

 Nutrition. surrounding them with outgrowths of its pro- 

 toplasm and so engulfing them. Ingestion 

 usually takes place at the hinder end of the animal. The 

 space in the body which the prey comes to fill would thus 

 be lined with ectoplasm, but the ectoplasm here becomes 

 absorbed into the sur- 

 rounding endoplasm, so 

 that it is clear that there 

 is no essential difference 

 between the materials 

 which compose these 

 layers. There is then 

 secreted around the 

 food particle a layer of 

 water containing sub- 

 stances which kill it and 

 digest its nourishing 



part. The reaction of Fig. Ji.—Amceba froleus in the act of 

 this fluid 4s acid at first, ingesting/, a small vegetable organ- 



but probably later be- ism which is t> ein g swallowed, 



comes .alkaline. The 



space containing the digestive juice is known as a. food vacuole. 

 The only organic matter digested by Amoeba is protein. The 

 dissolved substances are then incorporated and the un- 

 digested parts are egested by the simple process of being 

 left behind as the animal flows along. 



The protoplasm of Amoeba is irritable, automatic, and 

 : conductive. Its irritability is not, as in higher 

 animals, specially developed in sense organs, but 

 that this property exists in it is shown in various 

 ways. If it be stimulated by passing an electric 

 - shock through a drop of water in which it has 

 been placed, it will contract into a mass without pseudo- 

 podia. If it be pricked with the end of a fine thread of 

 glass it will draw back and flow away. In this case the 



Irritability, 

 Automatism, 

 and 

 Conductivity. 



