FILIPBROUS CAPSULES OF POLYPES. 



475 



even in one and the same individual very strongly marked diver- 

 sities are shown, of which a few examples are given in Fig. 233. 

 At A, B, c, and d, is shown the ap- 

 pearance of the "filiferous capsules," Fig. 233. 

 whilst as yet the thread lies coiled 

 up in their interior ; whilst 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. The most probable account 

 of their organization seems to be, 

 that each is a cell, of which one end 

 is extended into the thread-like or 

 dart-like prolongation, but which is 

 doubled in upon itself, in such a 

 manner that the armature appears to 

 be contained in its interior; and that 

 the springing out of the dart is due 

 to the eversion of the portion of the 

 cell which had previously been press- 

 ed inwards. These thread-cells are 

 found, however, not merely in the 

 tentacles and other parts of the ex- 

 ternal integument of Helianthoid 

 Zoophytes, 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 chambers. It was for- 

 merly supposed that the last-named 

 organs were always ovaria, and that 

 the long and slender filaments con- 

 tain sperm-cells and are consequently 

 the male organs. But since it has 

 been proved that the peculiar " fill- Fiiiferous copsuies of Heiiamhoid Po- 



ferOUS capsules" which lie side \,y hl>es:-A,^,Corynactu AUmanm; c^-r,^, 

 . T . . T /.i . n*^ Caryophyllia Smithii: d, g, Actinia crassi- 



Side m these filaments are reallj c^,i,;^^AcHnia Candida. 

 identical in structure with those 



which are found in the skin, the idea of their sexual nature has 

 been abandoned ; and a more careful examination of the organs 

 attached to the walls of the chambers has shown that these are 

 not always ovaries, but that they sometimes contain sperm -cells, 

 the two sexes being here divided, not united, in the same indi- 

 vidual. 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 protrude from rents in the external tegu- 

 ment, when any violence has been used in detaching the animal 

 from its base ; and when there is no external rupture, they are 



