SOME AQUATIC WORMS, ETE. 195 



and ftagments. The Turbellarians seem to prefer ani- 

 mal food, usually selecting Rhizopods and Rotifers, 

 but they are as fond of Infusoria, which must be as 

 nourishing and much more easily digestible.. I have 

 more than once lost an interesting specimen of Infu- 

 sorium because one of these Turbellarian worms had 

 been included under the cover-glass: there were a 

 worm and an Infusorium; a pause; a single snap, and 

 only the worm remained. 



Propagation takes place in two ways — by eggs and 

 by transverse fission; that is, one worm divides across 

 the middle and so makes two, each of these again di- 

 viding. And often before the division has been en- 

 tirely accomplished, both halves are also partly di- 

 vided, so that the single body seems to be formed of 

 several incomplete worms. The eggs of the common- 

 est species are brownish egg-shaped bodies, dropped 

 anywhere in the mud or the water, or they may have 

 a stem which attaches them to submerged objects, 

 from which they are easily broken. The last men- 

 tioned kinds of eggs may be readily recognized, be- 

 ing formed of a yellowish-brown, transparent chitinous 

 membrane, egg-shaped, and with the stem almost 

 equalling their own length. If the observer be for- 

 tunate he may see the worm escape by pushing off the 

 top of the egg, which falls away like a round cover, 

 leaving an empty case shaped like a deep cup. These 

 empty vases are often found at the bottom of long- 

 standing collections of plants in the microscopical 

 aquarium. 



The Turbellarian worms are common, but the ob- 

 server can scarcely hope to learn even the generic 

 name of those that he may find. He will be safe. 



