THE SLIPPER ANIMALCrLE 11 



shellac, containing a large number of slipper 

 animals, near a window ; agitate the water in 

 the dish so as to distribute the animals evenly. 

 Cover half of the dish with some opaque ob- 

 ject as a book or a piece of pasteboard, in order 

 to make one side of the dish darker than the 

 other. Let the dish stand quietly during four 

 or five hours of daylight. At the end of that 

 time examine the water carefully with a hand- 

 lens to see whether the animalcules have col- 

 lected more abundantly on the dark or on the 

 light side. Can the slipper animal see ? 



d. Reproduction. 



1. Fission. — How does this take place ? How does 



the process begin ? How long does it last ? 

 How many bodies result from it? "Which is 

 the " parent" and which the " child " ? What 

 becomes of the " ancestor " ? Is the process 

 common ? How do the resulting bodies com- 

 pare in shape, size, and structure with the orig- 

 inal? Can you detect, with or without re- 

 agents, that any changes take place in the 

 nucleus and paranucleus ? 



2. Conjugation. — How many individuals take part 



in the process ? How long does it last ? What 

 portions of the body are in contact? How 

 many bodies result from the process ? Is the 

 process voluntary ? How are two individuals 

 in process of conjugation to be distinguished 

 from one individual in process of fission ? Is 

 the conjugation permanent or do the individ- 

 uals separate again? How are the sexes dis- 

 tinguished ? Is any choice shown by those 

 2 



