1862 EDINBURGH LECTURES ON MAN 279 



appears as Part 2 in Man's Place in Nature, the first 

 lecture describing the general nature of the process 

 of development among vertebrate animals, and the 

 modifications of the skeleton in the mammalia ; the 

 second dealing with the crucial points of comparison 

 between the higher apes and man, viz. the hand, 

 foot, and brain. He showed that the differences 

 between man and the higher apes were no greater 

 than those between the higher and lower apes. If 

 the Darwinian hypothesis explained the common 

 ancestry of the latter, the anatomist would have no 

 difficulty with the origin of man, so far as regards 

 the gap between him and the higher apes. 



Yet, though convinced that " that hypothesis is as 

 near an approximation to the truth as, for example, 

 the Copernican hypothesis was to the true theory of 

 the planetary motions," he steadfastly refused to be 

 an advocate of the theory, " if by an advocate 

 is meant o'ne whose business it is to smooth over 

 real difficulties, and to persuade when he cannot 

 convince." 



In common fairness he warned his audience of the 

 one missing link in the chain of evidence the fact 

 that selective breeding has not yet produced species 

 sterile to one another. But it is to be adopted as a 

 working hypothesis like other scientific generalisa- 

 tions, "subject to the production of proof that 

 physiological species may be produced by selective 

 breeding ; just as a physical philosopher may accept 

 the undulatory theory of light, subject to the proof 



