RESPONSIVE LIFE OF ORGANISMS 485 



II. THE RESPONSIVE LIFE OF THE HUMAN SPECIES. 



Man in the organization of his body is a vertebrate animal. 

 So great is his likeness in structure to other vertebrates, we 

 should have no trouble identifying every organ in his body 

 from the study of the organs of the others. The functions 

 of the parts, too, are so similar that our knowledge of human 

 physiology has largely been derived from the study of other 

 vertebrates much of it even from the study of one so dis- 

 tantly related as the frog. But the slight physical differ- 

 ences existing between man and even the highest mammals 

 are accompanied by mental differences so profound that 

 our account of the responsive life of organisms would be 

 most inadequate without brief notice of mental develop- 

 ment in the human species. 



I. The natural history of man. 



We have not time to review the physical history of the 

 human body, its development from an egg, its segmen- 

 tation, its development of gill clefts and a fish-like 

 circulation that is subsequently altered to the mammalian 

 type, its nurture through embryonic membranes, its birth, 

 like that of any other mammal. These do not need to be 

 repeated. And we will not make mention of his mammalian 

 affinities, for these are sufficiently apparent. We will only 

 remark in passing that man's nearest zoological allies are 

 found among the anthropoid apes. The mammalian order 

 Bimana, (two handed animals), which a distinguished 

 zoologist of a past generation once erected as a pigeon-hole 

 in which man might be kept apart from the higher apes 

 (Quadrumana ; four handed animals) , has long been merged 

 in the great mammalian order Primates, which includes, 

 besides man and the apes, also the monkeys and the lemurs. 

 The zoological differences between man and the higher apes, 

 such as the orang, the chimpanzee and the gorilla, are far 

 less than the differences between these and the lemurs. 



