INFUSORIA 459 



ward when seeking prey, or to which It shrinks when 

 alarmed. 



In the former condition the body resembles a much 

 elongated Vorticella, with a similar circular orifice, set 

 round with cilia. Often the animal performs its ciliary 

 vibrations within the shelter of its house, not venturing 

 to protrude beyond its rim. If carmine be mixed with 

 the water, the atoms are seen in the customary vortex, 

 and some are occasionally drawn into the cell nearly half 

 way down its cavity, and then swiftly driven out again. 

 On a slight tap upon the table the animal withdraws, and 

 in the same moment the urn bends down upon its leath- 

 ery pedicle, at a point where there is always an angle, un- 

 til the rim of the cell is in contact with the plant to which 

 it is attached. This action is instantaneous. Presently, 

 however, it rises, and resumes its former position, and 

 then the mouth of the cell slowly opens, and the animal 

 again protrudes, the cilia appearing first, and finally the 

 head or front part of the animal, which is then opened 

 and begins to rotate. 



Very similar to this are the Vaginicolm, but the cells 

 which they inhabit are not^ stalked, but are immovably 

 affixed to plants. In F. crystattina, the cell is a tall 

 goblet, standing erect, perfectly colorless; while in F. 

 decumbens, it is slipper-shaped, attached along its side, 

 and of a golden-brown hue, but still quite transparent. 

 Here is, fortunately, a group of the latter species, scat- 

 tered about the leaves of the Nitella. 



Though, in general, both in form and habits, closely 

 like the Cothurnia, yet the Vaginicola has some peculiari- 

 ties of interest. The cilia are more developed, and can 

 be more distinctly seen than in either Cothurnia or Forti- 



