Another group, the Ciliata or Infusoria, of which Paramecium may be 

 regarded as typical, have a fairly constant body shape and propel themselves 

 by means of countless hair-like extensions of protoplasm called ''cilia", from 

 the Latin word for eyelash. These cilia, unlike pseudopodia, are always 

 extended and serve as oars to row the animal through the water. Although 

 the details of the arrangement of the cilia are hard to make out, yet, as a general 

 rule, if the animal moves at a fairly even gait, it is probable that the cilia are 

 almost all of the same length, while, if the gait is jerky and irregular, the cilia 

 are usually of unequal length or unevenly distributed over the body. 



A third group, the Fhgellata or Mastigophora, meaning the "whip- 

 bearers", have a few, long, protoplasmic processes or flagella, instead of many 

 short cilia. Euglena, the green organism that is on the border line between 

 plant and animal, is a common example, and so is the less common but ex- 

 tremely beautiful colonial form, Volvox. 



Another group, often classed as a subdivision of the Ciliata, is the Sue 

 toria. This group includes several odd Protozoa, most of which might be 

 confused with ciliates in their early stages and with flagellates in their more 

 mature form. Their protoplasmic extensions from the body are neither 

 cilia nor flagella, however, but sucking tubes, which enable them to prey on 

 other Protozoa. 



These generally accepted groups are not absolutely definite, for some 

 intermediate forms occur. Some amoeba-like animals pass through a flagellate 

 stage and some of the flagellates will move, especially when in the limiting 

 confines of a drop of water on a microscope slide, with an amoeboid motion. 



Many Protozoa use these characteristic structures for the intake of food 

 as well as for locomotion. Thus the pseudopodia or false feet of the rhizopods 

 flow around and incorporate particles of food into the bodily substance; some 

 of the cilia of the ciliates often serve to direct food into the mouth; the flagella 

 of flagellates may also be used to direct food toward the mouth area. The 

 stationary Suctona absorb nutriment through their sucking tubes. There is 

 some debate whether such border animals as Euglena take food as do other 

 flagellates or whether they synthesize food, as do plants, by means of the chro- 

 matophores that give them their green coloring. Probably they do both. Proto- 

 zoa feed on plant or animal material, either living or dead. Many of them eat 

 bacteria. Some of the larger forms are able to prey upon their fellow Protozoa 

 or other microscopic animals. 



The adaptation of Protozoa to environment is best demonstrated by their 

 means of enduring hard times. Most Protozoa, when drought or other 

 hazards threaten, eliminate all surplus moisture, thicken the outer coat, and 

 enter into a resting condition known as encystment. The animal, now re' 

 ferred to as a cyst, can endure drying, freezing, or almost any other natural 

 condition. Paramecium, for example, has a cyst stage in which it almost 



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