INFUSORIA. 1()9 



the fluid: some, as the Volvox, are globular; 

 others, as the Bodo* are shaped like a pear, taper- 

 ing at one end, and often terminating in a slender 

 tail, so as to resemble a tadpole. In many, and 

 particularly in the Enclilanis macrura, this tail is 

 of great length ; in some, as the Diglena, Euchlanis, 

 and Furcularia,'\ it is forked ; in others, as in all the 

 Vorticellce, it takes spiral turns, like a corkscrew ; 

 and in many of the Rotatoria it can be drawn out 

 and folded in like a telescope. The Euchlanis lyn- 

 ceus, and many of the Peridinia have processes 

 like horns. The shape of the Vibrio is cylindrical, 

 and more or less pointed at one or both ends, like 

 an eel, or a serpent, which animals it also resembles 

 in its undulatory mode of swimming.J Some, as the 

 Gonium, have an angular, others, as the Colpoda, a 

 waving outline, and many of the Rotatoria present 

 the likeness of a bell or funnel. In many species, 

 as in the Eaccillaria, Galiojiella, Navicida, Syncdra, 

 &c., the soft portion of the body is protected by a 

 hard covering, or shield, consisting of silica, and 

 capable of withstanding the effects of fire, as well 

 as most other disorganizing agents. 



Forms still more irregular are exhibited by other 

 infusoria. Of these the most singular is the Auiaba 

 difflmns, (Ehr.) better known by the name of Rro- 

 tens (Fig. 7U), which cannot, indeed, be said to have 

 any determinate shape, for it seldom remains the 

 same for two minutes together. It looks like a 



* Cercaria (Muller). f Furcocera, Lamarck. 



I Animalcules referable to this genus are met with in great num- 

 bers in blighted wheat, (Fig. 2, page 53) in sour paste, and in vine- 

 gar which has lost the whole of its alcohol. In this last fluid they 

 sometimes attain so large a size as to be visible to the naked eye. 



