INFUSORIA. 521 



among the Infusoria, animals apparently much more complicated, 

 and which only resemble them in their minuteness, and the dwelling 

 in which they are usually found. 



They will constitute our first order, though we must still insist 

 upon the doubts relative to their organization, which are not yet dis- 

 sipated. 



. ORDER I. 



ROTIFERA.(l) 



The Rotifera are distinguished by a greater degree of complica- 

 tion. Their body is oval and gelatinous; we can distinguish in it a 

 mouth, a stomach, and an intestine. It most commonly terminates 

 posteriorly in a tail that is variously constructed, and anteriorly it 

 bears a singular organ, variously lobate, with denticulated edges, and 

 of which the denticulations vibrate successively in such a manner as 

 to give the organ itself the appearance of one or more dentated and 

 revolving wheels. One or two prominences on the neck have even 

 appeared to some observers to be furnished with eyes. This re- 

 volving organ does not serve to direct their aliment to the mouth; it 

 may be supposed to have some connexion with the function of res- 

 piration. In 



FuRcuLAKiA, Lam. 



The body is unarmed; the tail is composed of articulations which enter one 

 into the other, and is terminated by two threads. 



It is on one of these — the Furcularia or Motif ere des toits — that Spallanzani 

 performed his famous experiments. Covered with dust in the spouts on 

 the roofs of houses it becomes desiccated, and after remaining in that state 

 for several weeks, reacquires life and motion on being humected with a lit- 

 tle water. 



There are two other genera, viz. Tubicolaria and Brachionus. 



(1) Wheel-bearers. 

 3 Q 



