ROTIFERS. 205 



glass a small drop at a time. This will dissolve 

 the soft parts, and permit the hard, insoluble mastax 

 to float out, when it can be examined with a high- 

 power objective. 



The Rotifers are reproduced by eggs, which are some- 

 times hatched within the parent's body, when they are 

 said to be ovo-viviparous. This, however, is not com- 

 mon. The eggs are usually semitransparent, ovoid bod- 

 ies, very often to be seen on the slide among other 

 matters, with the Rotifer partially developed, and the 

 mastax grinding away inside of the unhatched body 

 where it cannot possibly have anything to crush. The 

 only parallel to this of which I know is Professor Agas- 

 siz's statement that the jaws of the young snapping-tur- 

 tle snap while the creature is still in the egg. The Ro- 

 tifers may drop their eggs anywhere and leave them to 

 the care of Nature, or they may prudently attach them 

 to a leaf or some other aquatic object. Very often they 

 are adherent to the posterior part of the parent, and are 

 carried about until the young are hatched. In those 

 permanently attached Rotifers that form a soft sheath 

 this is a common occurrence, and several eggs may at 

 almost any time be seen in the lower part of the lorica, 

 or fastened to the animal's foot. In such instances, 

 when the young are hatched they creep up between the 

 parent's body and the side of the sheath and escape at 

 the front. They swim about for a short time, and then 

 secrete or build a sheath of their own, which they never 

 voluntarily leave. The eggs are usually smooth ; some- 



