78 N. E. GREEN ON CILIARY ACTION TN ROTIFERA. 



food, and reject the remainder. It is truly wonderful what an 

 amount of work they get through, considering the mass of material 

 which is constantly thrown on their hands, or, we should rather 

 say, their fingers. In Melicerta there are two cushions, each armed 

 with a phalanx of active cilia, which guard the entrance to the 

 gullet ; and when the supply of nutriment is too abundant they 

 close over the opening, and thus save the gizzard from repletion. 

 But in Brachionus, Philodina, and the common Rotifer, the inspectors 

 may be seen as a distinct series of hairs, and their duty is unmis- 

 takeable. 



When a particle has passed this ordeal it is allowed to enter the 

 gullet, where it is immediately taken up and hurried forward to 

 the gizzard by those cilia which line the passage, and whose action 

 is so constant as to raise the idea of running water. 



In a Brachionus a very peculiar movement was observed in the 

 throat when the stock of food was getting short. The cilia seemed 

 to form themselves into a writhing, tongue-like process, the move- 

 ments of which resembled a flame. This was sometimes thrust 

 towards the gizzard, and again turning in its course, stretched for- 

 ward to the mouth, as though anticipating the needed supply. 



It may also be observed that a movement of the cilia in the 

 gullet precedes the throwing out of the wheels ; and that in the 

 case of a poor Melicerta who had been evicted, this internal action 

 continued long after all exterior effort had been abandoned. 



When the gizzard is wanting, a most important duty t seems to 

 be assigned to the last of these internal cilia, viz. — the making up 

 of. the food into pellets. In some species of vorticella this has 

 been distinctly seen, the movement reminding us of that which is 

 observed in the mold of the Melicerta. The food seems also to be 

 amalgamated with some secretion of the animal, for instead of 

 mingling with the matter in the interior, it retains its globular form. 

 These pellets are then passed forward by a general action of the 

 interior, and reduced in size by absorption till they approach the 

 exit, where they sometimes coalesce before they are discharged. 

 The cilia covering the bodies of such creatures as the Stentors, are 

 evidently of great value, as by their continued action they cause 

 these discharged matters to pass away, which otherwise might ac- 

 cumulate, to the great annoyance of the animal. 



But we have not quite done with ciliary action yet, and 

 this last instance is, in our experience, unique. A rotifer re- 



