1 8 THE LESSON OF EVOLUTION 



ORGANIC EVOLUTION 



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, improve- 

 ments 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 evolu- 

 tion 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 

 variations from one generation to another. And in 

 psychological evolution mind is transmitted from 

 parent to offspring, as well as the organ in which it 

 is to be manifested. Intelligence, however, depends 

 not only on the structure of this organ, but on early 

 associations and education ; by which means the 

 wisdom of one generation is handed down to the next. 



