J 



66 ELEMENTARY BIOLOGY. [CIIAP. 



and the rolkd-in peristome. In this space the 

 ciha can frequently be seen moving. 



y. Structure; as in i. a. c: 

 b. The stalk ; thrown into corkscrew-like folds. 



o- 



The movements of Vorticella. 

 a. The ci/ia?'y movement. 



a. Examine the cilia carefully ; delicate homo- 

 geneous processes; their length, diameter and 

 form ; their position. 



p. The continuity of the cilia with the cortical 

 laver. 



y. The function of the cilia; their rapid move- 

 ments, alternately bending and straightening : 

 the co-ordination of these movements; they 

 work in a defmite order ; note the currents 

 produced in the neighbouring water (if neces- 

 sary introduce a few particles of carmine under 

 the coverslip); the sweeping of small bodies 

 down the gullet. 



/'. TJie movc7nents of tJie contfaeti/e vesicle. Tolerably 

 regular rhythmic distension and collapse (diastole 

 and systole). 



c. The currents in the endosarc carrying round the in- 

 gested bodies. 



d. The movements of the animal as a 7:>ho/e. (Ex- 

 amine under J inch or \ inch obj.) 



a. Its extreme irritability ; it contracts on the 

 slightest stimulation, often without any appa- 

 rent cause. 



/?. The movements which occur in contraction; 



