446 EVENINGS AT THE MICROSCOPE. 



capable of bending its head and body in various dii-ec- 

 tions, but is most beautiful when straight. The front 

 is furnished with a slender thread-like proboscis. This 

 species affords us a good opportunity of observing the 

 red spot which, for convenience sake, we may still 

 term an eye. It seems to be an irregular oblong 

 vacuole, or excavation in the sarcode, filled with a 

 clear ruby-red fluid. The red spot in the Rotifera is 

 connected with a well-defined crystalline lens, whose 

 definite form, and high refractive power, may in many 

 cases be distinctly marked ; but here nothing of the 

 kind is seen ; the spot itself has no certain shape, and 

 does not appear to be bounded by a proper wall. Some 

 forms, which are by general consent admitted to be 

 plants, have similar spots; and hence it has been, 

 rather too hastily, I venture to think, concluded, that 

 they can have no connexion with vision. I think it 

 still possible, that a sensibility to the difference between 

 light and darkness may be the function of the organ. 



I have found that this animal, when allowed to dry 

 on a plate of glass, retains its form and colour perfectly ; 

 but in about two days the eye-spot, which at first be- 

 comes much larger in the drying, gradually loses all 

 traces of its brilliant colour, probably by the evapora- 

 tion of the contained fluid. 



Another pretty species you see gliding along amongst 

 the rest, called £J. triqiietra, or the Three-sided. It 

 bears a resemblance to a broad rounded leaf, with the 

 footstalk forming a short transparent point, and the 

 raid-rib elevated into a sharp ridge. The under side 

 seems slightly concave. This is equally attractive with 

 the others. It is persistent in form, and appears not to 

 be even flexible. Its motion is slow, and as it goes, 



