60 HALF-HOURS IN THE GREEN LANES. 



others being permanently fixed, as the " crown- 

 animalcules." The male and female differ from 

 each other, the males being generally smaller than 

 the females. Indeed the former have a briefer life 

 altogether, as well as a less complex organization. 

 Their chief duty seems to be the fertilization of the 

 females, and that accomplished, their right to exist- 

 ence is gone. All the wheel-animalcules belong to 

 the annuloida, and in many of them there is a 

 distinct ringed appearance. Their organization is 

 relatively high. They possess a nervous system, a 

 distinct alimentary canal, mouth, and vent. Their 

 common name is derived from the anterior disk, 

 which is fringed with cilia; when the latter is in 

 rapid motion, it resembles the quick revolution of a 

 wheel. The respiratory apparatus, ovaries, etc., of 

 all these interesting creatures render them very 

 interesting to microscopists. The cilia of the disks 

 are in two or more sets. These wheel-animalcules 

 have the power of stretching themselves out and 

 retracting, like worms. Frequently their tail acts 

 as a claw, and enables them to anchor themselves to 

 aquatic leaves. The so-called " wheels " or ciliated 

 disks, can be drawn in at the animal's pleasure. 

 What renders the Eotifera most interesting to young 

 microscopists, perhaps, is that, owing to the trans- 

 parency of their bodies, you can see all the com- 

 plicated arrangement of the digestive and other 

 organs, and witness what is going on. The commonest 

 species, and one which you are almost sure to find in 



