Eyster: Heritable Characters of Maize: 
h. 
; 
A MAIZE PLANT WITH NORMAL CULM 
Compare these normal culms with the zigzag culms in the illustrations which follow. 
11 and 12.) 
ment to the two factor hypothesis the 
questions arose as to whether the defi- 
ciency in zigzag plants might not be due 
either to my inability to identify some 
of them or to a high death rate because 
of inherent weakness. So far as I have 
observed zigzag plants are as vigorous 
under field conditions as normal plants 
except that they are more apt to break 
in the internodes that are no longer 
clasped by the leaf sheathes. 
A number of F; plants were back- 
crossed with the zigzag parental type, 
eye) 
SAME PLANT WITH LEAVES REMOVED 
(Figs. 
and there resulted 373 normals and 104 
zigzag plants, a deviation of 134.5+7.4 
from the equality expected when par- 
ents differ in a single pair of factors, but 
a deviation of only 15.25+6.38 from 
a 3:1 ratio expected when parents differ 
in two pairs of factors. 
These data indicate that zigzag culm 
comes into expression only when at 
least two factors are recessive, and is 
another case of plural genes. Crucial 
tests of the hypothesis are yet to be 
made. 
