GENIC INTERACTION 



1 65 



account for the qualitative differences shown in figure 26. Thus c r and c a are inter- 

 preted as unable to produce any yellow whatever, even in cells with phaeomelanic 

 differentiation, c d is interpreted as relatively efficient in producing yellow, but less 



Fig. 25. EUMELANIN IN GUINEA PIGS AT BIRTH AND SIX MONTHS LATER. 



cV c r c a c r c r c d c a c d c r c d c d c k c a c k c r c k c d c k c k C 



4Eppff 



c a c a c r c a c r c r c d c a c d c r c d c d c k c a c k c r c k c d c k c k 



Estimates of amounts of eumelanin (above) in guinea pigs at birth (broken lines B, 

 dotted lines bb) and at about six months of age (solid lines). Similar estimates for 

 phaeomelanin (below) in guinea pigs at birth (broken) and at about six hours (solid). These 

 are based on unweighted averages of estimates from transformed visual grades (back as 

 whole) and transformed reflectionmeter readings (darkest spot near midline of back). 



efficient than c r in producing eumelanin because of this competition. It is more 

 efficient in the eyes (c d c d , c d c r , c d c a black eyed, cV dark red, c r c a light red) in which there 

 is no production of yellow and thus no competition. Gene c k is interpreted as somewhat 

 less efficient than c d in producing yellow but much more efficient in producing eumelanin. 



