120 DROPS OF WATER. 



The genus Vbrticella is one of the most in- 

 teresting amongst the Infusoria. The species 

 V. convattaria (Drop III. fig. 2) is the most 

 common, has a bell-shaped body, is perfectly 

 transparent, and attached by a flexible stalk of 

 considerable length to weeds, &c., so that it can 

 be watched with great ease ; and a more amusing 

 sight cannot be met with, than a number of 

 these beautiful beings grouped together, all 

 busily engaged in procuring food by the aid of 

 their cilia, which they keep in constant motion, 

 thus producing a strong current in the water, 

 and drawing into their mouths small atoms upon 

 which they feed. When any object alarms them, 

 they immediately contract the strong muscle, 

 which, with a power of 250 diameters, may be 



