M. E. Claparede on Actinophrys Sol. 215 



siders that KoUiker's observations are in accordauce with this, 

 as he also first saw the food lying in a pit on the surface of the 

 cortical layer, and supposes that KoUiker has overlooked the 

 previous moment in which the j)lace of the pit is occupied by a 

 caecal prominence. Kolliker's statement that any portion of the 

 surface may be employed indifferently as mouth or anus, is got 

 over by the supposition that although in general only two oppo- 

 site vesicular spaces in the cortical layer are protrusible, under 

 certain circumstances any other vesicular space at the surface of 

 the body may be more or less distended so as to be brought into 

 contact with any object that may be seized by the tentacles. 

 We shall, however, satisfactorily prove that this view is unte- 

 nable, and that the mode in which the reception of nourishment 

 takes place is not reconcilable with any such office of the pro- 

 trusible process. We have been fortunate enough repeatedly 

 to witness the feeding of Actinojjhrys, a ph?enomenon which has 

 escaped Stein, in spite of his careful observations, and can there- 

 fore assert that the reception of food is never effected by means 

 of the expansion and contraction of the vesicle. The contractile 

 vesicles {vesicular spaces of Stein) cannot be employed for any 

 other purpose, than, like a heart, to drive the nutritive fluid 

 into the substance of the body. Stein also wishes to prove that 

 the movements of the animal are produced by these vesicles; 

 this is also untenable. 



Kolliker, on the contrary, is perfectly right in stating that 

 " Actinophrys can convert any part of its body at pleasure into a 

 mouth, and employ it for the reception of food," and that it can 

 " also evacuate the indigestible portions at any point." Never- 

 theless I cannot entirely agree with his description of the pro- 

 cess of ingestion. According to his account, a pit forms itself 

 for the food in the substance of the body, and after the entrance 

 of the object, the margins of the pit approach and unite. It is 

 not, however, the food that penetrates into the substance of the 

 body, — it is rather the latter that approaches and embraces the 

 food. When an animal or plant comes accidentally v/ithia 

 reach of the tentacles of an Actinophrys, it remains adliering to 

 the sticky substance of which these appear to be composed. 

 The Actinophrys then slowly contracts the tentacle or tentacles 

 with which the prey is in contact, and before the latter has 

 touched the surface of the body, it is seen to be enveloped in a 

 kind of mucus. This mucus is completely undistinguishable 

 from the parenchyma of the Actinophrys ; it appears as though 

 the substance of which it is composed had suddenly drawn itself 

 over the captured object. The elevation thus produced then 

 slowly flattens, and by this means the food is gradually drawn 

 into the body (fig. 3). Astasia, which I frequently saw sucked in 



