18 Coelenterata. 



on the oral end of pieces (with the exception of a few heteromorphic tentacles 

 on very small oral pieces). Neither gravity nor contact affect the regeneration 

 of tentacles or the orientation of the individual. The apparent change of 

 orientation is only found in very small pieces, which, however, by means of 

 rapid growth at the place of the cut ultimately assume the same orientation 

 as that of the individuals from which they were cut, thus showing that even 

 the smallest pieces have a definite polarity. 



Richetf 1 , 2 ) 3 ) has separated from the tentacles of Actiniae two poisons very 

 different in their chemical properties and physiological action. Congestine is 

 insoluble in alcohol, it exerts powerful action on the vaso-motors of the in- 

 testine (of dogs). Thalassine is soluble in a mixture of alcohol and ether and 

 very small doses produce (in dogs) sneezing and violent itching, and in some 

 cases a rash and congestion of the vessels of the face. About 3 grms. of 

 thalassine may be obtained from a kilo of Actiniae. Thalassine possesses an 

 antitoxic power against congestine. 



Bourne ( 2 ) describes Lophohelia tenuis Moseley, Troohocyathus vasiformis, n. 

 and hastatus, n. from Funafuti. The flat discoid shape of young forms (3 to 

 4 mm. in diameter) of the last named and the presence of a large scar of 

 attachment on their upper as well as their lower faces show that they are not 

 stalked forms which have simply been detached at the base (as in some species 

 of Flabellum), but that they must have been formed by transverse division 

 of a fixed nurse-stock or trophozooid, a process extremely rare in corals (but 

 described by Semper in Fl. variabile). The scar of detachment is nearly as 

 large as the disc itself and it is clear that the young forms are not succes- 

 sively completed and then detached (as in Fungia) but that several young are 

 cut off from the trophozooid either simultaneously or in rapid succession. Al- 

 though the youngest specimen must have been only recently severed from the 

 trophozooid sufficient time has elapsed for processes of repair to set in, for 

 on the upper margin there are calcareous granules which have been recently 

 deposited on the truncated edge of each septum. The larger specimens show 

 greater repair and the oldest shows that the greater part of the corallum of 

 the adult, with its characteristic arrangement of septa and pali, is formed by 

 the upgrowth of the septa from the scar of detachment on the upper surface. 

 The costal spines of the adult are also the result of secondary growth. 



Duerden( 2 ) states that the polyps in Madreporaria which arise asexually by 

 budding are new individuals with all the characteristics of hexamerous cycli- 

 cal polyps reared directly from larvae, whereas in asexual reproduction by con- 

 tinuous fission no new polyps are ever formed. On any gemmiferous colony 

 a few polyps frequently occur which are much larger than the usual adult 

 form. The additional mesenteries and septa of these (as observed in Porites, 

 Madrepora, Cladocora, Stephanocosnia , Solenastrcea and Oculina] do not con- 

 tinue the hexameral cyclic plan of the polyp, but conform in character with 

 the mesenteries and septa already present and include one or two additional 

 pairs of directives. In Madrepora and Porites the new mesenteries arise 

 as complete or incomplete bilateral pairs within one or both of the directive 

 entocoels but in the other 4 genera mentioned they arise as unilateral isocnemic 

 pairs within one or more exocoelic chambers. Fission of the enlarged polyps 

 takes place in such a way that each of the 2 moieties resembles an ordinary 

 bud or larval polyp; each conforms with the hexameral plan and is provided 

 with 2 pairs of directives. Fission in gemmiferous corals (which seems best 

 understood as a modified form of budding fissiparous gemmation) is mor- 

 phologically distinct from the same process in fissiparous corals for in the 



