20 CORALS AND CORAL ISLANDS. 



low as was once supposed. For, besides the general sense of 

 feeling, some of them have a series of eyes, placed like a 

 necklace around the body, just outside of the tentacles. The 

 yellow prominences in this position on the larger figures in the 

 frontispiece are these eyes. They have crystaUine lenses, and 

 a short optic nerve. Yet Actiniae are not known to have a 

 proper nervous system : their optic nerves, where they exist, 

 are apparently isolated, and not connected with a nervous ring 

 such as exists in the higher Radiate animals. 



Reproduction is carried forward both by ova and by buds, 

 though the latter method is mostly confined to the coral-making 

 polyps. 



The ovarian and spermatic functions belong to the radiating 

 septa in the interior cavity of the Actinia, and to the part of 

 a septum, mesenteric in character, at or near the outer margin. 

 They have the aspect of a pulpy mass, or look like clusters of 

 ovules. The ova have no chance for escape except through 

 the stomach and mouth. They are covered with vibratile cilia, 

 and rove about free for a while. As the development of the 

 embryo goes forward, a depression begins at one end, which 

 deepens and becomes a stomach, with the entrance to it as a 

 mouth. Concurrently, septa grow out from the inner wall, and 

 a few tentacles commence to rise around the mouth. Not 

 unfrequently, the young has already some of its tentacles 

 before it leaves the parent. There is at first but a single row 

 of tentacles ; the number increases with the size until the full 

 adult limit is reached, the newer series being successively the 

 outer. 



In the budding process, which is of rare occurrence. Actiniae 

 grow young ones on their sides near the margin of the base. 

 A protuberance begins to rise and soon shows a mouth, and 

 then becomes surrounded by tentacles ; and, thus begun, the 

 new Actinia continues to grow, usually until its tentacles have 

 doubled their number, when finally it separates from the 

 parent and independent animal. At times, as Prof. H. James 

 Clark has observed, small pieces of the base of an Actinia 

 separate by a natural process before a trace of a tentacle has 



