140 THE EUCRATEA. 



animal, apparantly annoyed by the introduction into 

 the tentacular vortex of a mass of foecal matter recently 

 discharged, drive it out again forcibly, by altering the 

 current in some way : it was presently drawn in 

 again, and again driven forth; again and again it 

 returned. At length, as if convinced that other 

 means must be resorted to to get rid of the intrusion, 

 the animal suddenly bent inwards one of the tentacles, 

 and by a beautifully precise and momentary action, 

 pushed out the substance sideivays, or lifted it out as 

 it were, and it returned no more. 



Though very sensitive, — often, when in the midst of 

 full play, suddenly withdrawing in an instant within 

 the protection of the cell, and remaining there, perhaps 

 for hours, before it ventures to peep forth again, and 

 that without any cause of alarm appreciable by us, — 

 the animal is not easily induced to retract by any tap 

 or jar given to the table, or even to the vessel in 

 which it is held. Nor does the admixture of indigo 

 with the water cause it to suspend its motion, as is 

 frequently the case when we wish to administer pig- 

 ment to zoophytes. The colour is readily imbibed, 

 and affords, by its conspicuous visibility, an excellent 

 demonstration of the course of the digestive system. 



The form of the cells is liable to considerable 

 variation from that which is normal ; but not so 

 great as to make it all difficult to be recognized. 

 The degree to which the animal can protrude itself 

 differs greatly in different specimens, perhaps also 

 with the will of the animal. I have drawn one in ex- 

 treme extension, in which the distance from the base 

 of the tentacles to the margin of the cell was about 



