78 POND LIFE 



Parasitic rotifers will be frequently found happily rotifering 

 on the caudal fork appendages of Cyclops, also on the backs of 

 water-beetles, &c. Nematode worms occasionally show some 

 evidence of uneasiness, and on examination several parasitic 

 rotifers will be discovered, causing the trouble. Many species 

 of sedentary rotifers live on the stems and leaves of water- 

 weeds, and there, fastened by the foot, work away merrily. If 

 an intruder should blunder against it, the rotifer ceases work 

 and immediately withdraws the discs, and takes refuge behind 

 the weed. But as soon as quiet is restored it regains its 

 normal position, gradually opens the disc, and continues its 

 work. 



The Flosculariaceae contain Floscularia'cornuta, a common 

 freshwater species. Even ditches are inhabited by colonies of 

 this most beautiful creature. Each little animal is enclosed hi 

 a glassy gelatinous case. The head end is prolongated into 

 five finger-like processes, adorned with very fine hairs, which 

 are thought to act as a net in preventing the escape of organic 

 particles, and thus facilitating their capture. 



But the jewel of the Floscularia is Stephanoceros, the Crown 

 Animalcule. In this case the finger-like projections are elon- 

 gated, and are fringed along their entire length with cilia. 



The Melicertaceae build cases of bricks which are formed of 

 waste food. It is interesting to watch one of the Melicerta at 

 work. Each brick can be seen in the making, and when it is 

 ready, the rotifer suddenly bends backwards and neatly places 

 it on the top of the last layer. There is no hesitation nor 

 measuring, nor is a plumb-line used, and yet each brick remains 

 where it is placed. Gradually the case becomes larger and 

 larger until complete. The bricks, which are always made of 

 the same size and shape by the builder, are reddish-brown in 

 colour : for some time this colour was thought to be due to 

 iron, but it is now well known that the bricks, made of waste 

 food, are stained during the process of digestion in the rotifer's 

 stomach by a brownish fluid hence their colour. 



It is interesting to know that each species of Melicerta 

 makes its bricks of a particular shape. That the cases are 

 occasionally most curiously built structures will be seen if the 

 reader will refer to Hudgson and Goss's famous work on the 

 Rotifer. 



It so happens that, if one specimen be discovered, many will 

 soon be found, as the Melicertaceae /are of a social, or perhaps 

 better-termed gregarious persuasion, and owing to the size of 

 the case and the angle at which it is fastened to the stalk or 

 leaf, its discovery is simple, even without the aid of a lens. 



