CHAPTEE II 



ANCIENT LIFE ON THE EARTH 



WHEN, during the course of physical evolution, the 

 ocean had become sufficiently cool for the existence 

 of protoplasm, minute living organisms appeared on 

 its surface. These increased in size, varied in many 

 directions, and in time discovered the bottom of the 

 sea, on which they established themselves, changing 

 from swimming to crawling creatures. Gradually 

 these organisms managed to live in safety among 

 the rough waters of the sea-coast, and then they 

 spread over the land ; first the plants and then the 

 animals which came to feed on the plants. 



Once established on land, and breathing air, im- 

 provements in the circulatory system of the higher 

 animals became possible. The purified blood was 

 kept separate from the impure blood, and increased 

 rapidity of physiological processes heated the body : 

 so that, in the birds and mammals, a stream of pure 

 warm blood was poured upon the brain. Thus 

 stimulated, the brain developed rapidly; and the 

 psychological evolution thus inaugurated has reached 

 such a height in man as to place him mentally apart 

 from the rest of the animal kingdom. 



Biological evolution differs from physical evolution 

 in being brought about by the transmission of bodily 



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