AMOEBA PROTEUS 



45 



on the stems of ordinary water plants where amoebae and 

 allied forms are often abundant. Amoeba proteus varies in size 

 from Mooth to Ms tn of an mcn an( ^ undergoes different form 

 changes which at times make it difficult to recognize. There 

 is some question whether some of the forms described as dif- 

 ferent species of amoeba are not in reality one and the same; 

 the matter can be decided only by knowledge of the complete 



FIG. 18. Amoeba proteus in active moving condition, c.v., Contractile 

 vacuole; f.v., food vacuole; n, nucleus; p, remains of former pseudopodia; w.v., 

 water vacuoles. The arrows indicate the direction of protoplasmic flow. (From 

 Sedgwick and Wilson.) 



life history. Sometimes the organism is flattened or spatulate 

 in form, changing slowly, if at all, in shape. Again it becomes 

 a quickly moving drop of protoplasm quite transparent and 

 long drawn out as a single thread of substance. All interme- 

 diate grades between these forms are known, and in a general 

 wav the form and movements indicate states of nutrition, for 

 the flat spatulate types are usually dense with undigested food 



