112 J. MATTHEWS ON THE HISTORY AND 



multiples of five or six, and are tubular, usually retractile, smooth, 

 generally more or less conical, but sometimes thread-like, and mostly 

 richly coloured. You must all be familiar with these beautiful 

 flower-animals, so that I need not say more about their external 

 appearance. 



The soft smooth body consists of three layers — an outer (Ecto- 

 derm), inner (Endo-derm), and intermediate, more or less largely 

 developed (Meso-derm). It is provided with two layers of muscles, 

 probably developed in the meso-derm, the fibres of which are 

 antagonising, being longitudinal and circular. 



From the edge of the mouth is suspended a bag, which is the 

 stomach. This has an opening at its lower end, by which its cavity 

 communicates freely with the body cavity. Between the two are a 

 number of thin partitions or folds, called Mesenteries, which connect 

 them — some completely, others not — forming many interspaces, 

 called loculi, and inter-communicating freely, their number and that 

 of the tentacles generally corresponding, and the latter also open- 

 ing at their bases into these interspaces. All these cavities are 

 lined with innumerable cilia, -which keep up a constant circulation in 

 the water which is admitted by the stomach into the whole animal, 

 and which thus effect respiration, and, being mixed with the digested 

 food, nutrition also. 



In these creatures, as in the Hydras, reproduction is " con- 

 current " — i.e., it may be effected in the same organism by ovula- 

 tion, or by gemmation, or by fission, which last seems to be the 

 origin of the laminated forms of Corals which thus grow laterally. 

 But there is this important difference between them — that in the 

 Hydras it is wholly external, as I have before said, but in the 

 Actiniae and the Coral polyps, while the individual is multiplied by 

 buds, the species is multiplied by sperm and germ elements. The 

 situation in which these elements occur, and their mode of conjunc- 

 tion, are somewhat peculiar in this tribe. They may be hermaphro- 

 dite, but generally spermatozoa are developed in cysts in the mesen- 

 teries of the males, and when perfect are discharged into the 

 stomach, whence they are at once ejected by the mouth into the 

 water. In like manner the ova are first observed in the mesenteric 

 folds of the female, and when mature are discharged into that 

 cavity, which also receives the spermatozoa imbibed with the food. 

 Very few things are more wonderful to me than this circum- 

 stance, that the ovum remains in the stomach, after having been 



