RHIZOPODS. 119 



parts of the body, but usually they are on the rear end 

 only when the animal is moving. They often appear 

 very suddenly, and as quickly disappear. 



Yampyrella's favorite food seems to be the cell con- 

 tents of Spirogyrse. It selects a fresh and healthy plant, 

 and settling down upon it, proceeds to perforate the cell- 

 wall, and to remove the color bands with the entire cell 

 contents by drawing them into its body, leaving the cell 

 quite empty, with a ragged hole in the side. I have seen 

 one Vampyrella remove the contents from seven Spiro- 

 gyra cells in succession before its appetite was satisfied. 



3. ACANTHOCYSTIS CH^ETOPHORA (Fig. 94). 



Body spherical, soft, usually colored green by the 

 numerous green granules within. When the animal 

 changes its shape, which it seldom does, it only becomes 

 oval or slightly irregular in outline. The pseudopodia 

 are very fine and hair-like, springing from all parts of 

 the surface, but the peculiarity by which it may easily 

 be known is the dense growth of spines covering the 

 entire body, their ends being forked or divided into two 

 short, straight, diverging branches. To see these forked 

 ends demands a rather high-power objective, as they are 

 small, butf the spines themselves are apparent to a com- 

 paratively low -power. They seem not very securely 

 fastened to the animal ; some of them quite often be- 

 come loosened and drop off, especially if the Rhizopod 

 is not in a healthy condition. 



When food is to be taken into the body, a part of the 



