THE EVOLUTION OF MAN 



would at least have a nerve string, which could 

 later on develop into the spinal cord of a fish, 

 and below which the digestive tract would extend 

 in the form of a hose with one opening at each 

 end of the body. The entire form would have 

 no fin-legs, but would be a typical worm. This . 

 is the outline to which most of the present higher 

 worms actually correspond. 



At the same time we now find lower groups 

 of worms which evidently belong further back in 

 the scale. They have no complex nerve appara- 

 tus, no blood system and no opening at the lower 

 end of the body. We are justified in assuming 

 that they represent an older type, a sub-stage of 

 the worm type. In other words, within the worm 

 family we should have to look for man in various 

 disguises leading from the complex to the sim- 

 ple. There is still something else to consider. 

 In our system, apart from the vertebrates, there 

 are still three other great groups of invertebrates 

 which are of a higher organization than the 

 worms. They are, first, the crustaceans' spiders 

 and insects; then, the mollusks, such as snails, 

 muscles and octopus and finally the echmoderms, ** 

 such as star-fish, sea-urchins and related forms. 

 Not even the most daring anatomical speculation 

 can accomplish the miracle of deriving any one 



