GARDENS OF THE SEA 



187 



cause practically unseen. At times a stain 

 upon a rock, a discoloration upon a frond of 

 sea weed, may point to the presence of some 

 stray colony; but usually not even that much 

 sign is apparent. 



Not so with the sponges of the branch Porif- 

 era. They are marked features of the sea- 

 bottom because of their bulk, their wide dif- 

 fusion, and above all their varied colors. Time 

 was when they were considered plants, but they 

 are now positively placed in the animal king- 

 dom. They are many celled and have inhalent 

 pores through which sea water is drawn, and 

 minute animal life extracted therefrom. Their 

 forms are irregular — a mere fibrous network, 

 influenced as regards its shape by circumstances 

 and species. There are several classes, in one 

 of which the spicules are calcareous, and in an- 

 other of which they are siliceous, horny, or 

 glassy. To the latter class belong the glass- 

 rope sponges, the Venus flower basket and the 

 Neptune's cup. The sponge of commerce is 

 merely the dried skeleton of the animal with its 

 color bleached or faded in process of drying. 

 Alive and fastened to the rocks, their forms 

 expanded and their tints showing in masses of 

 light brown, yellow, red, or brilliant orange 

 they make up a remarkable sea-flooring. And 



Sponges. 



Kinds and 

 colors of 

 sponges. 



