CHAPTER I 



FACTS AND FACTORS OF DEVELOPMENT 



INTRODUCTION 



One of the greatest results of the doctrine of 

 organic evolution has been the determination of 

 man's place in nature. For many centuries it 

 has been known that in bodily structure man is 

 an animal; that he is born, nourished and de- 

 veloped, that he matures, reproduces and dies 

 just as does the humblest animal or plant. For 

 centuries it has been known that man belongs 

 to that group of animals which have backbones, 

 the vertebrates; to that class which have hair 

 and suckle their young, the mammals, and to 

 that order which have grasping hands, flat 

 nails, and thoracic mammae, the primates, a 

 group which includes also the monkeys and 

 apes. But as long as it was supposed that 

 every species was distinct in its origin from 

 every other one, and that each arose by a 



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