RHIZOPODS. 117 



animal changes its course, by emitting pseudopodia from 

 gome other portion, travelling off in the direction tow- 

 ards which they extend. The semi-fluid contents of the 

 body are colorless, unless tinged by the food or by the 

 presence of numerous dark particles. The movements 

 are sometimes quite rapid, the Amoeba extending its 

 pseudopodia, keeping them extended in advance, and glid- 

 ing along as though the body were formed of the white 

 of egg. In the figure it is shown with many short 

 pseudopodia, as it often appears immediately after it is 

 placed on the slide, and before it has learned where it is, 

 and has prepared to move in some definite direction. 

 The posterior extremity, when the Amoeba is in motion, 

 may be entirely smooth, or it may show a cluster of very 

 short pseudopodia, giving it a velvety or mulberry ap- 

 pearance. Suddenly a blunt, thick finger projects from 

 the part, and Amoeba at once reverses its course, the 

 pseudopodia at the front being withdrawn, and disappear- 

 ing in the substance of the body. The observer can 

 never predict what an Amoeba will do next. It is very 

 common in the ooze of shallow ponds and on the leaves 

 of many aquatic plants. Its body usually contains a 

 number of diatoms, which form part of its favorite food, 

 and it is a strange fact that the food is usually taken by 

 what, at the time, is the posterior extremity. There are 

 several species. 



1. Body large, colorless or blackish ; pseudopodia finger- 



like, blunt. Amosba proteus, Fig. 92. 



2. Body small, colorless, rather sluggish ; often floating 



