CHARACTERS IN AX UPLAXD-EGYPTIAX COTTON HYBRID. 53 
Most of the distributions assume approximately the form of a normal 
frequency curve, indicating that several factors are involved. Pro- 
nounced skewness is shown in several cases, however, and the F 2 
modes for a number of characters are much closer to the mean of 
one than of the other parental population. For corolla index, anther 
color, and seed fuzziness, the F, mean also showed a wide departure 
from intermediacy in the same direction as the mode of F 2 , indicating 
partial dominance. 
The only fairly clear cases of bimodal distribution in F 2 are given 
by the characters petal spot, anther color, and midlock furrow index. 
A monohybrid ratio for petal spot is suggested by the fact that 
approximately three-fourths of the F 2 individuals showed presence 
of the spot in greater or less degree, as contrasted with its total 
absence. In F 5 all individuals showed the spot present, but the 
great amount of variation in intensity in F x and in the portion of 
the F 2 population in which it was present indicates that several 
factors are involved in the degree of development of the spot, 
although its complete absence may be a simple recessive character. 
Data obtained in F 3 afford further indication, although not complete 
proof, that absence of petal spot is a simple Mendelian recessive and 
that modifying factors are concerned in its development, when present. 
The evidence points to the occurrence of a 3 to 1 ratio for anther 
color, light color of the anthers being recessive, and of a 9 to 7 
dihybrid ratio for midlock furrow index, presence of the furrow 
being recessive. 
Data obtained by other investigators of cotton hybrids give 
evidence of segregation in definite Mendelian ratios in respect to 
several characters which did not show discontinuous variation in the 
Holdon-Pima cross. 
Evidence of segregation in characters which did not give definite 
Mendelian ratios in F 2 is afforded by data obtained in the third 
generation of Holdon X Pima. Seventeen characters which did not 
show definite Mendelian segregation in F 2 were determined in 22 F 3 
progenies. For all of these characters the means of the F 3 progenies 
which gave the highest and the lowest mean, respectively, differed by 
an amount not less than twelve times the probable error of the differ- 
ence. There was a high parent-offspring correlation between the F 3 
progeny means and the values given by their respective F 2 parents, the 
average of the coefficients of correlation for the 17 characters having 
been 0.66 and the coefficients for all but one character having 
amounted to not less than four times the probable error. 
Further evidence of segregation is afforded by a study of the 
variability of the F 3 progenies. In respect to every character the 
coefficient of variation or standard deviation of the most variable 
and the least variable F 3 progeny differed significantly. As compared 
with the F 2 population, the most variable F 3 progeny was at least 
equally variable in respect to every character. As compared with 
the parental population which was the less variable for the character 
in question, the least variable of the F 3 progenies was significantly 
more variable in only 2 of the 17 characters. There was a ten- 
dency, although with many exceptions, for F 3 progenies 
individuals which occupied extreme positions on the frequency 
distribution of F 2 to manifest less variability than the F 3 pi 
of individuals whose position on the F 2 distribution curve 
intermediate. 
