66 THE OCEAN WORLD. 



a one as could be maintained. Neuremberg, Peyssonnel, and 

 Trembley maintained the animal nature of sponges, and their views 

 were adopted by Linnaeus, Guettard, Donati, Lamouroux, and Ehren- 

 berg on the Continent, and by Ellis, Fleming, and Grant in England. 

 Sponges live at the bottom of the seas in from 500 to 1,250 fathoms 

 of water, among the clefts and crevices of the rocks, always adhering 

 and attaching themselves, not only to inorganic bodies, but even 

 growing on algae and animals, spreading, erect, or pendent, according 

 to the body which supports them, and their natural habit. 



The power of fixing themselves to other objects, which certain 

 animals possess, is very singular ; nevertheless, it is certain that 

 whole tribes exist, the species of which are strictly adherent, which 

 live and die attached to some rock or other object, and among these 

 are the sponges. It follows then that but for their cilia they would be 

 wholly dependent on external agencies for their means of existence. 

 " The poor little creatures," says Alfred Fredol, " receive their 

 nourishment from the wave which washes past them ; they inhale and 

 respire the bitter water all their lives; they are insensible to that 

 which is only the hundredth part of an inch from their mouth." 



In the months of April and May these sponges develop ova 

 which are round, yellow, or white, and from whence proceed certain 

 ovoid granular embryos, furnished towards their largest extremity with 

 small vibratile cilia. They are either carried off by the currents, or 

 form swarms of larvae round the parent sponge. They swim about 

 with a gliding wavy motion, and when they have been some time in 

 the water they usually come to the surface. During two or three 

 days they seem to seek a convenient place to fix themselves. Once 

 fixed, the larval form loses its cilia, spreads itself out, and soon grows 

 into the form of its parent. 



" They soon attach themselves to some foreign body," says M. 

 Milne-Edwards, " and become henceforth immovable ; no longer 

 giving signs either of sensibility or of contractibilty, while in their 

 enlargement they are completely transformed. The substance of 

 tneir bodies is channelled and riddled with holes the fibrous frame- 

 work is completed the sponge is formed/' 



Their interior organisation consists of contractile cellules and 

 numerous spicula "a- tribe," says Gosse, "of the most debatable 

 forms of life, long denied a right to stand in the animal ranks at all, 

 and even still admitted there doubtingly and grudgingly by some 

 excellent naturalists. Yet such they certainly are, established beyond 

 reasonable controversy as true and proper examples of animal life." 



It may, indeed, be safely asserted that all naturalists are now 



