22 
Research Bulletin No. 4 
tion of some Mendelian factor for pericarp color in the 
somatic cells. The zygotic formula of a plant homozy- 
gous for variegated pericarp may be designated as VV, 
and that of a plant heterozygous for variegated pericarp 
as V — . If in any somatic cell VV, from unknown causes, 
a V factor were transformed into a factor for self-color, 
S, that cell would then have the formula VS. Any peri- 
carp cells descended from it would without further modi- 
fication be red. If all the pericarp cells of a seed were 
thus descended, the seed would be self-red, just as it would 
if the plant bearing it were a hybrid between pure red and 
variegated races. Moreover, one half of the gametes 
arising from such somatic cells would carry V and one 
half would carry S, just as if the plant were a hybrid of 
red and variegated types. Or, if both V factors were 
changed, the grains would be self-red as before, but all 
instead of half the gametes would carry S. If, however, 
the modification from VV to VS should occur very early 
in the life of the plant, or even of the embryo, all the ears 
of the plant might thereby become self-red, and one half 
of all the gametes both male and female might then carry 
S and the other half V as in the ordinary hybrid. Or the 
plant might then become a sectorial chimera with one 
variegated ear and one red ear, the gametes from the one 
side of the plant all carrying V. If the modification 
occur much later, say soon after the ear begins to form, 
there might then be merely a solid patch of red grains on 
an otherwise variegated ear. In this case only those 
gametes arising from these smaller masses of tissue would 
carry half S and half V. If, however, the modification 
occur after the grains begin to form, the latter might be 
perhaps three fourths red, or one half red, or merely have 
narrow stripes of red, depending upon the amount of peri- 
carp directly descended from the modified cell. In this 
case it seems reasonable to assume that the larger the 
mass of modified tissue the greater the chance that the 
