MICROSCOPICAL STUDIES. 79 



is that they all combine in the possession of so many and so well 

 developed subsidiary mesenteries that in section the apparent com- 

 plication becomes bewildering and confusing beyond measure to the 

 student to understand, to the teacher to explain. 



The representative used to illustrate the second sub-class, is the 

 common Alcyonium, a colony of polyps cemented together by a 

 gelatinous or semi-cartilaginous matrix strengthened by calcareous 

 spicules. On some parts of our coasts it is plentiful, forming when 

 living and with tentacles fully expanded, an exquisite feathery mass 

 of life — strangely contrasting with the woeful, gruesome appearance 

 it takes on when dead, and battered, and cast up, a sea-waif, upon 

 the beach. Fishermen give it all sorts of names expressive of their 

 loathing, " Deadman's fingers," " Deadman's toes," " Cow's paps," and 

 the like. 



The colony is formed of tiny, anemone-like polyps, — each with a 

 row of eight pinnate tentacles, — united together by a wonderful develop- 

 ment of the mesoglaea ; indeed a distinctive name is now applied to 

 this tissue — coenosarc — and it adds a great defensive device against 

 predatory enemies, by the development within its substance of 

 curiously warted spicules of carbonate of lime. And these tiny flesh- 

 spines are not only found in the connecting matrix, but even in the 

 thin layer of mesoglaea of the oesophagus are some smaller ones. 



Note the different number and arrangement of the mesenteries. 

 Instead of being in pairs, they occur in two series, a right and a left, 

 and the muscular swellings face downwards (towards the siphonoglyph) 

 in each series. Fig. 6 shows a section cut low down in the stalk of 

 the colony, a region equivalent to that of Siphonactinia shown in 

 Fig. 2 ; here the mesenteries are reduced to low folds or ridges. 



Reproduction is rather different ; the ova and sperm masses are 

 not produced in special glands in the substance of the mesenteries, 

 but arise singly in bud-like fashion on the edge of the mesenteric 

 ridges (ov' and ov). 



Besides Alcyonium, there are several other and diverse repre- 

 sentatives of this class found on our shores. There is the lovely, 

 light-emitting Sea-Pen (Pennatula) ; the equally curious if less 

 elegant Virgularia, and the grand Sea-Fan or rather Sea-Bush, 

 Gorgonia verrucosa. The organ-pipe Coral (Tubularia) and the 

 true red Coral (Cor allium rubrum) are also members — their ul- 

 timate structure being identical with that of Alcyonium as described 

 and figured, and differing almost solely in the method of spicule 

 arrangement : in the one, loosely scattered ; in the other, densely 

 packed and soldered intimately together. 



