ANTHOZOA HELIANTHOIDA. 187 



open in the spaces between the perpendicular lamellee. These 

 spaces being filled, the water is then made to permeate the 

 rim of the oral disk, which is full of cavities and cells for its 

 reception ; and the tentacula are in the same manner dis- 

 tended, the water being forced into them from behind while 

 the little opening on their tips is held close. The whole ani- 

 mal is thus distended to a wonderful degree, and every organ 

 stretched and displayed ; — the tentacula spread out in quest 

 of prey, — the skin rendered almost clear from very fulness ; 

 and the stomach, pushed beyond its natural bounds, often lies 

 over the sides in swollen diaphanous lobes. The water thus 

 introduced is doubtless subservient to the purposes of respira- 

 tion ; and to aid this, the vermiform filaments, and the in- 

 ternal surface of the stomach and tentacula are clothed with 

 vibratile cilia, exciting and directing currents over the sur- 

 faces.* Since too the contents of the stomach must be fully 

 exposed to the influence of the water, the nutrient parts may 

 be by its means fitted for more immediate assimilation, for as 

 there is neither circulating nor -lymphatic systems, the absorp- 

 tion of the nutrient fluids must be made directly from the 

 stomach itself. By the contraction of the periphery of the 

 body, this water is again expelled at pleasure through the ten- 

 tacula in a continuous stream or in jets, and if the contraction 

 is sudden and strong, the water may be thrown ou.t with such 

 force as to rise to the height of at least a foot. It is remark- 

 able that the water does not escape from all or the greater 

 number, but only from a few of the tentacula. Whether any 

 part escapes by the mouth has been doubted, but I have seen 

 it ooze thence too often to join in the doubt. The water, too, 

 in the Actinia crassicornis and its allies, is often ejected in a 

 small stream from the perforated tubercles of their skin, and 

 with such a degree of force that the jet will rise to a height of 

 not less than four inches. 



TActinie se relache, penetre par quelques tentacules, et des qu'elle se contracte, sort 

 par d'autres tentacules precisement opposes aux premiers. Ce phenomene s'observe 

 sur toutes les especes d'Actinies." 



* Sharpey in lib. cit. i. C14-15. — There is a distinct circulation within the tube 

 of the tentacula, unconnected apparently with any circulation within tlie body. A 

 cm-rent may often be seen, even with a common magnifier, setting up towards tlie 

 apex, where it is turned and sets in the contrary direction ; but before the stream 

 has reached the base, it again has turned, and retakes its centrifugal direction. 



