Chapter III Sponges 



THE sponge, so familiar to us all since 

 our early childhood, forms a fascinating 

 link in the chain of evolution, standing 

 midway between the simple single-celled 

 animals and the mass of complex forms 

 which by their ever-increasing efficiency 

 culminated in the perfect animal man. 

 The ancients regarded sponges as being 

 members of the vegetable kingdom, and 

 their generation was, in fact, at one time 

 attributed to a fermentation of the sea 

 scum. As recently as 1785 the great 

 naturalist Linnaeus, failing to appreciate 

 their true position in the system, classi- 

 fied them as plants. 



Sponges are hatched from seed-like eggs 

 no larger than pin heads. They develop 

 into free-swimming individuals furnished 

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