riH THEORY OF E^'OLUTION 



ti) recessive characters. Tlie next one is 

 dominant. 



A single male ap2)eare(l with a narrow verti- 

 cal red bar [tig. 81) instead of the broad red 

 OA'al eye. Bi-ed to wild females the new char- 

 acter was foniid to dominate, at least to the 

 extent tliat the eyes of all its offspring were 

 narrower than the noi'mal eye, althongh nf)t so 

 narrow as the eye of the jjure stock. Around 



Fig. 3;3. Mutant i-ace of fruit fly, called speck. There is a 

 luinute black s])eck at liiise of wini>;. 



tlie bar there is a wide border that cor- 

 responds to the region occupied by the rest of 

 tlie eye of the wild fly. It lacks however the 

 elements of the eye. It is therefore to be 

 looked ujjon as a rudimentary organ, which is, 

 so to speak, a by-product of the dominant 

 mutation. 



