SECT. T. ROTIFERA. 165 



head form two circular currents in the water, like 

 whirlpools, which draw all floating particles into their 

 vortices, and the streams from the two whirlpools uni- 

 ting into one current, flow off horizontally and pass im- 

 mediately over the slit on the ventral side of the animal. 

 Some of the floating particles are arrested by the cilia 

 on the edges of the slit, and are drawn into the sunken 

 mouth by the vibrations of the cilia in the tube. The 

 edges of the slit act like lips, and seem to possess the 

 sense of taste, or of some modification of touch, which 

 enables them to select from the particles presented to 

 them, such as are fit for food ; these are admitted into 

 the mouth, where they are bruised by the powerful jaws. 

 The mouth or masticating apparatus is the most extra- 

 ordinary and complex part of this animal. It consists 

 of two horny toothed jaws, acting like hammers upon an 

 anvil. The two hammers, which approach each other 

 from the dorsal sides of the body, are each formed of 

 two parts united by a hinge ; the first parts correspond 

 to the handles ; the second parts, which are bent at 

 right angles to the first, resemble hands with five or 

 six finger-shaped teeth united by a thin membrane. The 

 teeth are parallel to one another when they meet on the 

 anvil, and are seen through the transparent mass tear- 

 ing the food into fragments. Some of the Rotifers re- 

 semble the Errant Annelids in being able to turn this 

 complicated machine inside-out through the ciliated 

 tube and slit, so as to bring it into contact with the 

 water. When the food has been masticated it is sent 

 into the stomach, where it is digested. The whole of 

 this process is seen through the transparent and colour- 

 less body of the Brachion, because its favourite food 

 is the Syncryn velox, a minute bright green plant, which 

 from its active motions was at one time believed to be 

 an animal. 



The Brachion has four longitudinal muscular bands 



