INFUSORIA. 411 



like the Cothurnia, yet the Vaginicola has some peculia- 

 rities of interest. The cilia are more developed, and 

 can be more distinctly seen than in either Cothurnia 

 or Vorticella, forming, when in swift action, a filmy 

 ring above the margin, along which, as if upon a wheel, 

 one or more dark points are frequently seen to run 

 swiftly round : the optical expression, as I presume, of a 

 momentary slackening in the speed of the wave. The 

 act of self- division takes place in this animal, as in the 

 Vorticella; and it is curious to see two Vaginicoke, 

 exactly alike, lovingly inhabiting the same cell. One of 

 the cells which we are now examining is in this doubly- 

 tenanted condition. 



I will now exhibit to you some examples of the most 

 highly-organised forms of this class of animals, in which 

 we discern a marked superiority over any that we 

 have yet looked at, and a distinct approach to those 

 animals whose more precise movements are performed 

 by means of special limbs. These creatures are very 

 common, both in fresh and sea water, wherever vegetable 

 matter is in process of decomposition; and hence their 

 presence can at all times be commanded by keeping 

 infusions. In this old infusion of sage leaves, for 

 instance, they occur in vast multitudes, past all imagi- 

 nation, as you may see with a lens in this drop. 



This group belongs to the genus Stylonychia, and, as I 

 believe, to the species S. pustulata. It presents the form 

 of an oval disk, which, when seen sidewise, is found to be 

 flat beneath and convex above. It commonly swims with 

 the belly upwards, and, when exhibited on the stage of 

 the microscope, in almost every case, this surface is pre- 

 sented to the eye. It darts about very irregularly, with 

 a bobbing motion, rarely going far in one direction, but 

 shooting a little distance, and then instantly receding, 

 turning short round, and starting hither and thither, so 

 fitfully that it is very difficult to obtain a fair sight of its 



