EADIATA. 



Eleetra Verticillata. a Natural size. 

 b Magnified. 



Section of living Sponge. 



Flustra Dentata. mngnifip 



or tumbling about above the substances near it. Finally, becoming stationary, a margin gathers round th 

 body, and the centre, growing transparent, shows within an inanimate Polypus. 



Among the varieties of the Cellariaea are the Lunulites Radiata, found in Grignon; the Lunellte en part 

 to/, of Defame; the Eleetra Verticillata, of Gmelin; the Flustra Dentata, found in the northern seas; th 

 Flu>tr.i Carbasea. found in the seas of Scotlarr, v he Phcrusa Tubuloza, of Ellis and Solander; the Cellari 

 Ceroide*, of Gmelin, found in the Mediterranean, and the Indian seas; and the Unicellaria Cheluta, fount 

 in the seas of North America. 



The class, Porifera, presents so complete a commixture of the characters of animals and plants, that i 

 is hard to say to which division they belong. On the one hand, like plants, they are fixed to one spot 

 possess^!, apparently, of no sensibility, and seem to have no power of voluntary motion. On the othe 

 hand, their structure is unlike that of plants, and resembles that of creatures belonging to the anim; 

 kingdom. They are, therefore, commonly assigned to the latter, but at the lowest point on the scale. 



The Sponge is a familiar variety of this class, which may serve to represent the whole. What we cm 

 and ust; as Sponge is, however, but the skeleton of the creature. When alive, this fibrous network i 

 dollied, within and without, by a thin, gelatinous substance, very similar to the white of an egg Thi 

 substance drains away, on the Sponge being taken from the water. During the Sponge's life, it not onl 

 grows, regularly, but there is a constant flow of water in and out through, its pores. These currents coi 

 vi-v nutriment into the interior of the mass, and carry off excretions. 



Sponges, like plants, may be multiplied by artificial division, each portion becoming a new indi vidua 

 Their natural mode of increase, however, is by detaching from themselves little, round, gelatinous botlie: 

 called gemmules, which in time become counterparts of the parent. 



Some kinds of Sponges are found on almost all shores ; and some frequent deep water, whence they ca 

 only be obtained by dredging. It is in this manner that the common Sponge is procured from the Med 

 tenanean, the Grecian Archipelago, and the other localities it frequents. Sponges are not confined to th 

 sea, however ; for there is a species which inhabits fresh water. 



f384) 



THE END 



