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not know that the same Power which, as Newton remarked, caused 

 the apple to fall to the ground, is the author and director of all 

 laws, whether they affect the physical or the animal world. 



The Sponges are found fossil in the oldest rocks. They attain 

 their maximum in the chalk. Most of our flints have a Sponge 

 or its spiculse as a nucleus, round which the silicious mattter has 

 accumulated. 



With this chapter my history of the Protozoa finishes. In my 

 next I shall treat of beings a step higher in the scale of existence. 



