MARVELS OF THE POND. 



123 



in a tangled mass in our jar, or waving in delicate 

 filaments towards the surface. Having placed it in 

 a small trough or live-cage, we had better examine 

 it first with an inch objective. Here is something 

 worth a good long look. It is a tiny transparent object 

 which seems to be moored to a 

 twig, and is surmounted by a 

 couple of wheel-like organs which 

 appear to be incessantly revolv- 

 ing. It is at once pronounced to 

 be a Rotifer, or wheel-animalcule. 

 Having found it, we proceed to 

 examine it with a rather higher 

 power. Suppose we use a half- 

 inch lens. We can make the 

 change in a moment, for our 

 nose-piece is one in which three 

 objectives can be screwed, and 

 all that we have to do is to give a 

 slight turn to this nose-piece and 

 the half-inch is in position at once. 

 We have now a spectacle that, if 

 one has never seen it before, is sure to be pronounced 

 one of the most beautiful and curious ever beheld. 

 Here are the wheels apparently turning round with 

 astonishing rapidity, and just under them is a giz- 

 zard actively at work. These wheels are not really 

 turning round, but they are made up of a circle of 

 fine hairs, called cilia, which are lashing the water 

 in quick succession, and that begets the illusion of 

 revolution. If our eye-lashes were whipping the 

 air in a similar fashion, it would really seem as if 



FIG. 29. 



Rotifer rndgaris. 



