12 
BULLETIN 1489, U. S. DEPARTMENT OF AGRICULTURE 
well as. in those that are homozygous dominant (A A,C C,R R). No 
red develops, however, in kernels that are homozygous recessive for 
any one of these three pairs, regardless of the conditions of the other 
two. Thus, kernels of the constitution A A, C C, r r; A A, c c, R R; 
and a a, C, R R, always are colorless because of r r, c <?, and a a, 
respectively. 
Ps4/?EA/TS'. 
COLORLESS fad) 
COLORLESS (tr) 
/?EPfiODl/CT/lfE 
CELLS 
F,C/?OSS: 
flED/ILEUffONEfaaffr) 
f?EPffODCSCr/l/E 
cells: 
FOUf? MA/ OS 
(/CAf}),(/Ca/yj/CAr),(/Car). 
Fig. 6. — Diagram of the method of inheritance when more than one factor pair is in- 
volved. Two strains of corn with colorless aleurone are crossed. One of these 
(i, i, G G, pr pr, A A, r r) is colorless because it contains r r. The other (i i, C C s 
pr pr, a a,~R R) is colorless because it contains a a., This aleurone of the F ± cross 
is red, as it receives A r from one parent and a R from the other, thus being 
A a, R r. Four kinds of reproductive cells are formed in this generation, as can 
be determined either by appropriate crosses or by self-fertilization. The parents 
are both harmozygous i i, G C, pr pr. All of the reproductive cells therefore 
carry i, G, pr. For simplicity, pr is not shown in the figure 
The action of A, C, and R as outlined in the preceding paragraph 
is based upon the assumption that the parents of the cross were 
homozygous for both pr pr and i z, the two remaining factor pairs. 
The factor pr is allelomorphic to Pr, which determines the formation 
of purple rather than red in the aleurone. Pr being dominant, 
kernels carrying A C R are purple if they carry either Pr Pr or Pr 
pr. Under these conditions, therefore, Pr converts what otherwise 
