26 POND LIFE 



yet continuing to feed, seemingly totally indifferent to their 

 visitor. 



But usually, they are most sensitive to touch, and will 

 remain in retirement some little time, if very violently inter- 

 fered with. 



Whilst some bell animalcules live more or less inde- 

 pendently, others again are surrounded by a jelly-like 

 substance. 



Ophrydium is often found as a lump of jelly Jth of an inch 

 in diameter. Under the microscope it will be seen to be the 

 home of many hundreds of vorticella-like creatures. Each 

 minute animal is able to withdraw or extend in search of 

 food, whenever it may wish to, perfectly independent of the 

 remaining colonists. 



Although most of the bell animalcules seem to prefer a 

 social life to a solitary one, a few species are the exceptions, 

 and live quite independently, the most beautiful of these 

 being Cothurnia, Umbellula, Vaginicola, and others. 



Two very interesting experiments may be performed with 

 these little creatures. If a solution of iodine be added to the 

 slide of living vorticella, the nuclei of the cells will im- 

 mediately take the stain. 



Vorticella feeding may be watched, and the course of the 

 food followed, by allowing a very small quantity of Indian ink 

 to run under the cover glass. 



The little specks of black will be caught in the vortex, and 

 taken in by the animalcule, but after some attempt to digest 

 them, the Indian ink particles are returned to the water. 



SUCTORIA 



The Suctoria contain some most curious little animals a 

 good example being the Acineta, Each little creature, less than 

 Y^th of an inch in length, stands on a hardened stalk, which 

 terminates in a triangular cup -like structure. Out of the 

 corner of the cup, arms are thrust, each arm ending in a little 

 knob. In some species the arms are able to open into tubes, 

 through which the food is drawn. 



Should an unfortunate creature, such as a small rotifer, 

 come into contact with one of these tentacles, its doom is 

 sealed, for the other suckers bend over towards the victim. 

 Gradually the fluid portions of the rotifer are sucked out, 

 until nothing but the solid portions remain. 



By what power the Acineta is able to hold its prey, is 



