110 BOMBAY DUCKS 
us not be mistaken. I do not deny the adequacy of 
natural selection to produce new species. Undoubtedly, 
numberless species have arisen as the result of the 
weeding out of the unfit; but it seems to me that 
natural selection alone is unable to explain organic 
evolution. It is undoubtedly a factor in the origin of 
species and probably the most important factor, but it 
appears to be but one of many factors, several of which 
have yet to be discovered. 
