r6tifers. 227 



the acceptable morsels and passes them on to the mas- 

 tax; a second current carries away the fragments for 

 which she has no use; and the third sets in towards 

 the little organ that makes the pellets. This is a 

 small cavity into which the building material is 

 poured,* and where it is turned about rapidly by the 

 fine cilia which line it. An adhesive secretion is 

 exuded that causes the particles to adhere to one an- 

 other, and the revolving motion gives the pellet the 

 shape of a Mini6-bullet, or, in another species, makes 

 them spherical. When the -pellet is formed to the 

 Rotifer's liking and all is ready for the final act, Meli- 

 certa rotates or twists herself in the tube bends her 

 body forward, and deposits the pellet on the top row 

 exactly in the right place, and there she cements it 

 fast with an invisible, insoluble cement. The entire 

 act is performed so quickly, that the first time the ob- 

 server sees it he is so surprised that he sees nothing. 

 It is remarkable that, as a rule, Melicerta forms a 

 pellet while standing at that side of the sheath oppo- 

 site to the point where she intends finally to place it. 

 There are two somewhat common species in our 

 waters, one making almost spherical pellets {Melicerta 

 ringens), the other forming her "bricks" in the shape 

 of the Minie rifle-bullet [Melicerta conifera), with the 

 conical extremities pointing outward. 



6. LiMNiAS (Fig. 159). 



The attached sheath formed by this Rotifer is a 

 rather rigid, always membranous, and nearly cylindri- 

 cal tube, yet somewhat widest in the upper region. 

 When young it is usually colorless and smooth, but it 

 changes with age, becoming brown or blackish, and 



