CHAPTER IV 



BRANCH TROCHELMINTHES : THE ROTIFER AND ITS 



ALLIES 



THE ROTIFER, OR WHEEL-ANIMALCULE 



Find the specimen with the low power : some are likely 

 to be moving about the field too rapidly to be studied; 

 others may be temporarily fixed at the base, and simply 

 moving within an area represented by the length of the 

 body. These are the ones to study. If none such are 

 found, extract the surplus water from beneath the cover 

 glass with a piece of blotting-paper, to quiet some of the 

 active Rotifers. In the study use both the high and low 

 powers of the microscope. 



I. — Can you see two different ways of locomotion — one a 



crawling movement, the other a free-swimming move- 

 ment.'' Describe each. Do the Rotifers always go 

 forward when moving ? How does the locomotion of 

 the Rotifer compare with that of the Amoeba .■" Is there 

 a distinct differentiation into anterior and posterior 

 parts .'' Is the movement in a definite dirfection ? 



II. — What decided difference can you see between the gen- 

 eral structure of this creature and the other microscopic 

 animals (like Paramecium, Stentor, or Stylonychia) you 

 have studied .'' Is the Rotifer a one-celled animal ? 



III. — Study and describe the tail-like structure on the pos- 

 terior end of the body. Does it move from side to side, 

 or disappear within the body, or both .'' 



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