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Fig. i6. Typical Forms of Protozoa or Single-Celled Organisms. 



A. Amccba proteus, one of the soft, unprotected, jelly-like organisms which rank among the simplest known 

 animals. They are continually changing form by thrusting out or withdrawing the lobe-like projections 

 known as pseudopodia, which are temporary prolongations of the cell-body for purposes of locomotion or 

 food capture. Any part of the body may serve for the purpose of food ingestion, which is accomplished 

 by simply extending the body so as to surround the food. Magnified 200 times life-size. After Leidy. 



D. A colony of flagellates or Mastigophora, showing a number of individuals in variou.s stages of their life his- 



tory. They are distinguished by one or more whip-like prolongations which serve chiefly for purposes of 

 locomotion. As, contrasted with the Amxha. many of the flagellates have definite, characteristic body 

 forms, and have the function of food ingestion limited to a special area of the body. Magnified 285 times 

 life-size. Photographed from a model in the .\merican Museum. 



E. A typical ciliate, one of the most highly organized single-celled forms, distinguished by a multitude of fine 



hair-like cilia, distributed over the whole or a part of the body, which are used for locomotion and for 

 the capture of food. In some forms these cilia are grouped or specialized for further effectiveness. After 

 BUtschli Magnified 180 times life-size. 



