166 



PHYSIOLOGIC GENETICS 



The top lines in the upper and lower parts of figure 23 compare the various c compounds 

 in the most favorable combinations with other loci. 



Returning to figure 22, the intensity of phaeomelanin is represented as affected 

 by F (strong) and/ (weak) at 14 and 15 in figure 22 following reaction 13 and as subject 

 to a threshold (at 1 7) . What is left is represented as interacting (at 18) with a limiting 

 factor 2 (Lph) to give yellow pigment. The averages in figure 23 show a slight 

 reduction brought about by replacing FF by Ff and great reduction by replacing it by 

 ff. The absence of yellow pigment in the heterozygotes represented collectively by 

 c kd c ra ff, in contrast with the small amounts in c kd c kd ff, is one of the evidences for a 

 threshold. Great differences in the intensity of reds, eeCF, among inbred strains 

 (about twice as much pigment in strain 32 as in strain 2) indicate a variable ceiling. 

 Crosses indicated multiple factors, 2 (Lph). 



Turning to the eumelanic colors, P (or an allele p r described by Iljin 626 as similar 

 in effect to P except for lighter eye color) is represented as necessary for the production of 



Fig. 26. Mean quality index (Q) plotted against mean intensity index (/) for 



VARIOUS GENOTYPES. 



Q 



50 

 48 

 46 

 44 

 42 

 40 

 38 

 36 

 34 

 32 



Cream (ee) 



c d c a - 



cd c d ffc d c d^ xckcd 

 v\ 



Eppff 



> CFf 



« CFF Red M 



White 



(upper quartile 



• Pale brown 



cdcMcr (EbbppF) 

 .d r d_ x ^_ rd r d 



Dark brown 



cc 

 Very pale 

 sepia 



dn + , Jc<« u, ;f j 



Dark sepia 

 (EBP) 



EbbP 



cic k cfc r c r 

 Black 



10 20 30 40 



Both indices are derived from reflectionmeter readings. 



50 I 



