ALCYONAKIA 



879 



\J 



thread lies coiled up in their interior ; and at E, F, G, H are seen 

 a few of the most striking forms which they exhibit when the thread 

 or dart has started forth. These thread-cells are found not merely in 

 the tentacles and other parts of 

 the external integument of Ac- 

 tinozoa, but also in the long fila- 

 ments which lie in coils within 

 the chambers that surround the 

 stomach, in contact with the 

 sexual organs which are attached 

 to the lamellae dividing the cham- 

 bers. The latter sometimes con- 

 tain ' sperm-cells ' and sometimes 

 ova, the two sexes being here 

 divided, not united in the same 

 individual. What can be the 

 office of the filiferous filaments 

 thus contained in the interior of 

 the body it is difficult to guess 

 at. They are often found to pro- 

 trude from rents in the external 

 tegument, when any violence has 

 been used in detaching the animal 

 from its base ; and when there is 

 no external rupture they are often 

 forced through the wall of the 

 stomach into its cavity, and may 

 be seen hanging out of the mouth. 

 The largest of these capsules, in 

 their unprotected state, are about 

 ^^th of an inch in length ; while 

 the thread or dart, in Corynactis 

 Allmanni, when fully extended 

 is not less than Jth of an inch, 

 or thirty-seven times the length 

 of its capsule. 1 



Of the Alcyonaria a character- 

 istic example is found in the Alcy- 

 onium digitatum of our coasts ; FIG. 666. Filiferous capsules of Acti- 

 a lobed sponge-like mass, covered nozoa: A, B, Cori/nactis Allmanni; 

 with a tough skin, which is com- c t > , E > ?> OaryophyUiaamithiii D, G, 



T -, , . , Actinia crassicornis ; H, Actinia can- 



monly known under the name of dida. 



1 dead-man's toes,' or by the 



more elegant name of ' mermaid's fingers.' When a specimen of 



this is first torn from the rock to which it has attached itself, it 



contracts into an unshapely mass, whose surface presents nothing 



1 See Mr. Gosse's Naturalises Rambles on the Devonshire Coast, and Professor 

 Mb'bius, ' Ueber den Bau u.s.w. der Nesselkapseln einiger Polypen mid Quallen,' in 

 AbhandL Naturw. Vereins zu Hamburg, Band v. 1866. On the relations of stinging 

 cells to the nervous system, see Dr. v. Lendenfeld, Quart. Journ. of Microsc. Sci. n.s. 

 xxvii. p. 393. On the stinging cells of Coelentera generally, see N. Iwanzoff in Bull. 

 Soc. Moscow, 1896, pp. 95 aiido'23. 



