THE LOWER FOEMS OF LIFE. 67 



stituted the germ, while the small inferent openings, termed pores, 

 and the large efferent openings, termed osculae, being established, 

 the process of feeding, so essential to growth in all animals, goes on 

 prosperously. The food entering by the pores is thoroughly digested, 

 and those particles which are not nutritious are rejected through the 

 osculae. This food appears to consist of particles of either animal 

 or vegetable matter, or both. Bowerbank thinks that some of the 

 internal defensive spiculae are used for the purpose of destroying 

 any live creature which may be drawn among them. Other 

 spiculse are used as organs of prehension that is, of attaching 

 the Sponge to the rock ; others are used as special organs of 

 defence to the sarcode and the ovarium containing the gemmules. 

 These spiculae are many of them very beautiful microscopic forms ; 

 in fact, Bowerbank figures and describes at least 240 different 

 varieties. 



Such is a simple statement of the life history of a Sponge. As 

 it does not grow continuously, but is subject to periodical periods of 

 development, I cannot give any real data about the time occupied 

 in the growth of any of the large species in our shop windows. If, 

 however, two or more Sponges of the same species come into 

 contact, they will join housekeeping and become united into a 

 single Sponge. Different species, however, decline any such intimate 

 association. 



It will have been noticed in my short description that, in some 

 respects, the Sponges possess a higher degree of organisation than 

 any of the animals before noticed. For instance, they can close the 

 osculse and open them at their will. By closing them they stop the 

 fountain, which when open flows from them, This shows the 

 possession of a power bordering on that of muscular fibre ; and this 

 is one of the reasons why Kolliker places them at the head of the 

 Protozoa. 



To my mind there is something marvellously interesting in the 

 economy of the Sponge. How beautiful a provision is made for the 

 tiny speck which floats by its cilia through the world of waters in 

 search of the rock which is to be its home ; how wonderful its 

 system of spiculee, all of which it is able to form according to its 

 wants, now for defence, now for prehension, now for attack, and 

 always for support to the horny-like fibrous covering within which 

 it is to live ; how marvellous the reproduction of its germs and all 

 this in an animal which, to the most searching eye of science, shows 

 no more organisation than a layer of glue or jelly ! But the will ! 

 the power to open and shut the oscula capriciously, and to expel 

 the water with great force therefrom, just as it has occasion to do 

 so ! All this is truly wonderful, and would be inexplicable did we 



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