ix.] THE BELL-ANIMALCULE. 97 



[& Conjugation; the attachment of a small free 

 swimming bell to the side of a stalked one.] 



[t. Encystationj the body contracted into a ball and 

 surrounded by a thickened structureless layer, 

 the contractile vesicle being persistently dilated.] 



B. Other forms closely allied to Vorticella which may be 

 met with, and which will do nearly as well for exami- 

 nation, are ; 



a. Epistylis. Bell-shaped animals growing on a 

 branched non-contractile stalk. 



b. Carchesium. A form very like Vorticdla but borne 

 on a branched contractile stalk. 



c. Cothurnia. An almost sessile form, provided with 

 a cup or envelope into which the bell can be re- 

 tracted. 



[The activity of the movements of the free Infusoria inter- 

 feres with the complete examination of the living animal It is 

 well therefore to add a little osmic acid solution to the drop of 

 water under examination. This kills such Infusoria as Para- 

 mczcium, Nyctotherus and Balantidium instantly, without de- 

 stroying the essential features of their organization.] 



