LUTHER BURBANK 



place by infinitesimal stages, on the basis of 

 natural selection. 



A slight shift in position of the eye of the flatfish 

 would have no utility whatever. It is only when 

 the shift has become sufficient to bring the eye on 

 the upper side of the fish that the creature would 

 have any advantage over other flat fish whose eye 

 is on the under side. 



If we imagine a mutation in which a fish 

 appears with an eye distorted in location suffi- 

 ciently to be usable while its owner lies flat on 

 its side in the mud, we can readily understand 

 how such a mutation might be favorable to the 

 individual and thus might furnish material for 

 the development through natural selection of a 

 race of flatfish having both eyes on one side. 



We have every reason to believe that the 

 races of flatfish now existing have recently — • 

 in a geological sense — developed their observed 

 condition of having the eyes thus located; indeed 

 proof of this that amounts to demonstration is 

 furnished by the fact that the young flatfish even 

 to this day is born with its eyes located like those 

 of other fishes, the migration of the eye, so to 

 speak, taking place as the individual develops 

 the racial habit of lying on its side. 



But as I said, it is unquestionably difficult to 

 conceive how the useful distortion came about 



[92] 



