64 THE OCEAN. 



and at the end of four weeks the water was found 

 to be still pure, the Mollusca and other animals all 

 alive and active, the Confervce had grown percep- 

 tibly, and the Coralline itself had thrown out some 

 new shoots, and several additional articulations. 

 Eight weeks have now elapsed since the experi- 

 ment was begun, — the water has remained un- 

 changed, — yet the Coralline is growing, and appa- 

 rently has lost none of its vitality ; but the animals 

 have sensibly decreased in number, though many 

 of them continue to be active, and show no dis- 

 like to their situation. What can be more conclu- 

 sive ? I need not say that if any animal, or even a 

 sponge, had been so confined, the water would long 

 before this time have been deprived of its oxygen, 

 would have become corrupt and ammoniacal, and 

 poisonous to the life of every living thing."* 



Who is not familiar with Sponge, — with its soft- 

 ness, its elasticity, its capacity of absorbing and re- 

 taining fluids, and other qualities which render it so 

 valuable in domestic economy ? And yet how few 

 are aware that it is the skeleton of an animal ! In 

 fact, Sponge is one of those dubious forms which 

 God has placed in the great system of Creation, on 

 the confines of the two great divisions of organic 

 beings, apparently having little in common with 

 either. Like the Corallines, the Sponges have af- 

 forded occasion for much controversy as to their 

 proper position ; but they are now pretty unani- 

 mously assigned to the animal kingdom. The com- 

 mon Sponge of household purposes (Spongia offici- 



* British Sponges, p. 215. 



