70 PRACTICAL ZOOLOGY. 



system, and organs of sight and hearing, show the rotifer 

 to be much more highly developed than the protozoans. 



Rotifers have been dried and kept for years, and yet 

 when put into water they revived. 



Study carefully — 



1. The mode of locomotion. 



2. The action of the disks and cilia. 



3. The motions of the pharynx. 



4. The contraction and expansion of the body as a 

 whole. 



Make drawings showing the body both in the expanded 

 and in the contracted state. 



Read the " General Characters of Rotifers " in Packard's 

 " Zoology " ; " Rotifera " in Claus and Sedgwick's " Text- 

 Book of Zoology." 



THE FISH. 



Let each pupil have a live minnow in a fruit-jar. 

 Watch the movements of the mouth and gill-covers at the 

 sides of the head. Observe the motions of the eyes. Can 

 a fish wink? Does a fish sleep? Study the action of 

 each fin, trying to discover what work is done by each. 

 What is the chief propelling power ? Consider the fitness 

 of the shape of the body for locomotion in water. 



THE EXTERNAL FEATURES OP THE FISH. 



For this work, and the dissection which follows, the 

 perch is preferable, but bass or croppies serve very well. 



