122 ORGANS OF ATTACHMENT, 



transparent bodies of the animalcules, but in the poriphe- 

 rous animals the dense silicious and calcareous spicula which 

 compose their solid frame-work are supported and maintained 

 in their positions by a more tough, elastic and firm portion 

 of the general cellular tissue of the body, perhaps stimu- 

 lated to condensation by the presence of these earthy crys- 

 talline bodies. By the motions of the body, produced by 

 external bodies, the points of these sharp spicula are made 

 to project from this tough connecting matter in various 

 directions from the gelatinous surface of the body, from the 

 margins of the pores, or into the internal canals. The tubu- 

 lar filaments in the horny species anastomose with each 

 other freely throughout the whole body, like the continuous 

 connecting matter in the earthy species. The jointed ap- 

 pearance seen in most flexible tubular keratophytes, as ser- 

 tularia, plumnlaria, campanularia, is confined to the exterior 

 covering, and does not interrupt the course of the fluids 

 circulating through the enclosed fleshy part. These thinner 

 portions and annular strictures of the horny covering allow 

 of the more ready development of new branches, cells, or 

 vesicles, and of the incessant movements of all their parts 

 produced by the ever-restless sea. The branches of the 

 cellaria thuya drop off regularly from below upwards along 

 the stem, at these apparent joints. The minute calcareous 

 spicula of many corticiferous and fleshy zoophytes, as gor- 

 gonia and lobularia, are connected by the general cellular 

 substance of the body. The black, flexible, elastic matter 

 deposited in concentric layers between the calcareous inter- 

 nal solid pieces of the isis hippuris, are merely uncalcified 

 portions of the common animal matter which pervades the 

 whole skeleton, and connects all its earthy particles ; they are 

 like the uncalcified portions of corallines, but are secreted, 

 as the calcareous matter of the skeleton, by the enveloping 

 fleshy crust. The exterior sharp spines of pennatulte are 

 connected and moved by the coriaceous irritable skin of the 

 body. The skeletons of zoophytes, as those of higher tes- 

 taceous animals, are insinuated into the minutest inequalities 

 of the surface of rocks, and thus adhere firmly, by being 

 exuded in a soft semi-fluid state, and then condensing. The 

 cartilaginous, internal, reticulate filaments of many alcyonia 

 are continuous, like those of horny poriphera, throughout 



