PLANARIA 67 



TURBELLARIA 



PLANARIA MACULATA 



This form is very common in fresh-water ponds through- 

 out the United States. It is found during the day on the 

 lower or shaded surfaces of stones and other submerged ob- 

 jects, a fact which suggests that it is nocturnal in its habits. 

 Most fresh-water planarians have very opaque bodies and 

 their internal organization cannot be studied in the fresh 

 specimens. 



1. Notice the general shape of the body. 



2. The methods of locomotion. Look for cilia. 



3. The pharynx and mouth near the middle of the ven- 

 tral surface. 



4. The eye spots on the anterior dorsal surface. 



5. Try feeding specimens by crushing a live pond-snail 

 and putting the fragments in the dish with them. If any of 

 the worms are at rest, set them in motion by lifting one end 

 of each with a bit of wood, a camel's-hair brush, or some 

 blunt instrument. Observe the animals at intervals of a few 

 minutes and see if any of them begin to feed. If so, by turn- 

 in them over quickly with a camel's-hair brush, try to see 

 how the pharynx is used. If not successful, try turning a 

 specimen ventral side up, and placing a small bit of snail 

 meat on its body in the region of the pharynx. 



6. Look among the specimens in the dishes on the prep- 

 aration table for animals that show marks of normal fission. 



7. Clean a heavy watchglass thoroughly and pour it about 

 two thirds full of clean pond water from the jar on the 

 preparation table. Transfer all of ^the specimens to this dish, 

 lifting each carefully with a camel's hair brush. With a 

 scalpel mutilate them in various ways; cut one transversely, 

 another longitudinally, another into several pieces of various 

 shapes. Make memoranda, if necessary, of the shapes of the 

 various pieces. Carefully cover the dish and set it away. 

 Examine the pieces with a hand lens every twenty-four hours 



