6 BULLETIN 1489, IT. S. DEPARTMENT OF AGRICULTURE 
INHERITANCE OF JAPONIC A STRIPING IN CORN 
There is a type of leaf striping known as japonica (pi. 4), and 
strains of corn can be obtained that breed true for this character 
(S3). Other strains can be obtained that breed true for all green, 
or at least for the absence of this striping. If two such strains are 
crossed, the first generation plants, or F 1 plants as they are called, 
will not show the japonica character. The japonica character there- 
fore is said to be recessive to the normal green which is the dominant 
condition. 
If the F x plants are crossed with japonica, about half of the plants 
in the next generation will be green and the rest will be japonica. 
The japonica plants will breed true if pollinated among themselves. 
If the green plants are crossed with japonica, the result will be as 
before, namely, the progeny will consist of 50 per cent green and 
50 per cent japonica plants. No* matter how often green plants 
obtained in this way are mated back with japonica, the progeny 
always will consist of green and japonica plants in a ratio of about 
one to one. 
There is no additive effect from the repeated inbreeding of japon- 
ica. Neither is there any intermediacy or blending. A plant either 
is green or it is japonica. The green plants may, and probably 
will, exhibit some of the many other stripings or spottings common 
in corn, and the japonica plants will vary in the degree of striping, 
but this has no bearing on the inheritance of the japonica character 
itself. 
These are the observed facts. It is assumed that there is a single 
pair of factors involved. One of these, which may be called /, is a 
factor for normal pigment formation in the corn plant. The other 
so alters the plant processes that pigment is formed only in certain 
parts of the leaves, giving rise to japonica striping. This factor may 
be called j, in keeping with the custom of symbolizing a recessive 
factor by a small letter and its contrasted dominant factor by the 
same letter capitalized. 
The body cells of the true-breeding green parent contained a 
double set of / and may be represented J /. Similarly, the japonica 
parent may be represented by j j. All of the reproductive cells of 
the green parent would carry only / and the reproductive cells of 
the japonica parent would carry only j. The fertilized eggs from 
which the F x plants were produced, therefore, would contain both 
the factor for normal green and that for japonica. These F x plants 
consequently may be represented as / j. The presence of / dominates 
that of j completely in this case, and the plants are green. 
The reproductive cells of the F x plants are of two kinds. One- 
half carry ./ only and one-half carry j only. Therefore, when the 
F x plants are mated back to japonica plants the reproductive cells 
of which carry only j, two kinds of fertilized egg cells are formed, 
namely, j j and J j, and these are produced in equal numbers. The 
former will produce japonica plants and the latter green plants 
that are entirely similar to those of the F v The behavior of the 
factors in the case outlined is shown graphically in Figure 3. 
Factors that operate as ./ and j, in opposition to each other as it 
were, are called allelomorphs of each other, and the characters they de- 
