CAHPENTEK. — FEEDING REACTIONS OF THE ROSE COKAL. 157 



The feeding reactions of the third genus, Caryophyllia, have been 

 described briefly by Carlgrcn ( : 05). The cilia of the oral surface of 

 this coral beat inward near the mouth, and outward in the peripheral 

 region external to the tentacles. Food is brought by tentacular action 

 into the circum-oral region, whence it is conveyed by cilia to the mouth 

 and stomodaeum. Contractions of the oral disk and peristaltic move- 

 ments of the gullet assist in the swallowing of large objects. 



The feeding process in the related group of alcyonarian corals has 

 been studied by Pratt (: 05), who shows that in Alcyoniam digitatum 

 food is taken into the gastro-coelomic cavity by means of the muscular 

 activities of the tentacles and gullet. Cilia are not mentioned as being 

 concerned in the process. Within the body of the zouid both inter- 

 cellular and intracellular digestion take place through the agency of 

 the mesenterial filaments. 



It therefore appears that in all coral polyps heretofore investigated 

 the food reaches the coelenteron and is here digested by the mesen- 

 terial filaments. But in Isophyllia the evidence points to an improve- 

 ment in the method of appropriating food, which makes the polyp of 

 this genus a very efficient plankton trap. It apparently does not risk 

 losing its prey by attempting to transfer it by tentacular or ciliary 

 movements to the mouth, and thence through the gullet to the usual 

 digestive cavity. On the contrary, it affixes its prey firmly to its ten- 

 tacles, and then, inclosing its captives in a more or less complete, 

 though temporary, chamber formed on the external surface, it proceeds, 

 by means of its mesenterial filaments, to digest its food in situ. 



Allusion has been made to the statements of the morphologists in 

 regard to the scarcity of food fragments in the coelentera of preserved 

 madreporarian polyps. Whatever the reason for this may be in the 

 case of other corals, in Isophyllia the failure to find such materials is 

 readily explained by the extra-coelenteric digestion of at least the 

 greater part of its food. 



Evidences of Nervoid Transmission. The term " nervoid " is here 

 used in preference to " nervous " because of the failure of the histolo- 

 gists to demonstrate differentiated tissues of undoubted nervous char- 

 acter in the polypal wall of the great majority of the Madreporaria, 

 including Isophyllia. Duerden (:02) mentions the presence of a dis- 

 tinct ectodermal nerve layer in the tentacles of some species, — 

 "Cladocera, Madrepora, and probably others," — but in his special 

 description of a representative of the genus Isophyllia no reference is 

 made to such a layer. A weak ectodermal muscle layer seems, how- 

 ever, to be of constant occurrence in the tentacles of the Madreporaria. 

 As far as the polypal wall is concerned, Duerden and Ayres (: 05) state 



