lo Laboratory Guide in Zoology 



III. — Study the contractile vacuoles. How many can you 

 find.? 



IV. — Near the middle or front of the body find a mass 

 of food material contained in a well-defined spherical 

 cavity, somewhat larger than the contractile vacuole. 

 This is called the excrement vacuole. Indigestible 

 matter from all parts of the body is forced into this 

 vacuole, whence it is extruded through the body wall. 

 Egestion may, however, take place at other points. 



V. — By careful focussing, make out the longitudinal stria- 



tions of the Stentor. These are due to a differentiated 

 portion of the ectosarc, by the contraction of which 

 shortening of the body takes place. Determine whether 

 there are cilia all over the surface of the body. 



VI. — See the remarkable chain-like nucleus along one side 

 of the body. It can frequently be distinguished before 

 staining, but if it is not visible in your specimen, add 

 some staining solution to bring it out. 



VII. — Make a good-sized drawing of the Stentor, showing 

 the parts visible when it is stretched out. Make also 

 a sketch showing its shape when contracted. 



THE STYLONYCHIA 



In the first search for Stylonychia remember that it is 

 shorter than the Paramecium, although it resembles the 

 latter somewhat in general shape. 



I. — Observe tHe quick, jerking movement in its locomotion. 

 By the use of a bit of blotting-paper, draw out some of 

 the water on the sHde, to restrain its movements so that 

 it may be studied with the high power. Watch the ani- 

 mal carefully to determine its anterior and posterior ends. 

 Try to see if there is a rotary movement of the body. 

 Determine whether it has a dorsal and a ventral side. 



