iGS THE MICROSCOPE. 



are popularly supposed to do so, and at any rate possess 

 some peculiar power of adhesiou. Iu all these cases, organ 

 and function may be said to go together ; but the cells are 

 also present in the majority of jelly-fish which do not 

 urticate, in ^Eolids which do not urticate, and in Planarice 

 which do not urticate. Here, then, we have the organ 

 without any corresponding function; urticating cells, 

 but no urtication. It thus appears that animals having 

 the cells, have none of the power attributed to the 

 cells ; and that even in those animals which have the 

 power, it is only present in the tentacles, where the cells 

 are much less abundant than in parts not manifesting the 

 power ; the conclusion, therefore, presses on us, that the 

 power does not depend upon these cells. When at rest, 

 and in an ordinary natural state, the animal is never seen 

 to dart out these threads, nor upon capturing his prey; it 

 is only when some force is used to dislodge him from some 

 spot to which he has, securely attached himself, that he 

 presses or squeezes out these threads ; more for the pur- 

 pose of compressing himself into a closer and smaller 

 mass, to add to the difficulty of detaching him. 



"Actinice do not effect their preparation of nutriment by 

 chemical means ; that is, they do not, in the strict sense of 

 the term, digest, but simply derive nourishment by mecha- 

 nical pressure, exerted upon any particle of food that they 

 may draw into their stomachs. This has been proved by 

 experiments made after the manner of Reaumur. A small 

 piece of meat having been put into a quill, and allowed to 

 remain in the stomach of the Actinia sufficiently long, and 

 then withdrawn, no solvent fluid is found to have acted 

 upon it. When placed under the microscope the muscle 

 fibres are not at all disintegrated, and the strias are as 

 perfect as before the experiment, with the exception of a 

 pulpiness and loss of colour, as in any ordinary mechanical 

 maceration. 



" Light has been thrown upon the reproductive system 

 of the Actinice by M. Jules Haime, in the Annates des 

 Sciences Naturelles, 1854, 4 ieme serie, torn. i. ; which con- 

 tains accurate and detailed descriptions and plates of the 

 disposition of ova and spermatozoa in the Actinice. To 

 find the ovaries it is only necessary to take a live animal, 



