CHARACTERS IN AN UPLAND-EGYPTIAN COTTON HYBRID. 29 
PETIOLE HAIRINESS. 
In the Holdon-Pima hybrid the Fj mean for petiole hairiness indicated a slight 
tendency to dominance of the practically glabrous condition of the Pima parent. 
The F 2 frequency curve (fig. 15) was extremely skew, approximately two-thirds of the 
population having been as glabrous or nearly as glabrous as Pima, while a few 
individuals were much hairier than the Holdon parent. 
Balls (4, p. 25), working with an upland-Egyptian cross, reported that the glabrous 
condition of the Egyptian parent was dominant in Pj. An F 2 progeny contained 111 
glabrous and 37 hirsute individuals — an exact 3 to 1 ratio — and in another F 2 progeny 
the numbers were 53 glabrous and 17 hirsute. _ Of four F 3 progenies of F. ? individuals 
which had been classed as glabrous, two contained only glabrous individuals, while 
the other two each contained a few hirsute individuals. In a later publication (6, 
pp. 140, 141) Balls states that complete dominance of the glabrous condition does 
not occur in F! and that the segregation in F 2 and later generations is such as to 
indicate that several factors are concerned. Certain F 5 families are stated to have 
" bred true to new types of hirsuteness. ' ' 
McLendon (34, p. 1S5), dealing with upland-sea-island hybrids, reports the hairi- 
ness of the upland parent to be incompletely dominant in Fj and that the F 2 fre- 
quency distributions extended "from one extreme to the other." 
PETAL COLOR. 
Petal color, in the Holdon-Pima hybrid, gave an intermediate and uniform F, 
and a unimodal frequency curve in F 2 , extending from one to the other parental 
extreme. (Fig. 26.) The F 2 mode was intermediate, but the number of individuals 
which had the petals lighter colored than the intermediate shade greatly exceeded 
the number having deeper yellow petals. 
Fletcher (18), crossing a red-flowered with a yellow-flowered Indian cotton, ob- 
tained in Fj approximately equal numbers of reds and yellows. Second-generation 
progenies Of red F t 's comprised 428 red-flowered and 114 yellow-flowered indi- 
viduals (rati'o 3.75 to 1) while F 2 populations grown from yellow F^s comprised 474 
yellow-flowered and only 12 red-flowered individuals. Balls (2, p. 367) is doubtless 
correct in his interpretation of this result that the red-flowered parent was heterozy- 
gous, containing a factor for yellow, and that the presence of a few red-flowered 
individuals in the F 2 populations from yellow-flowered Fj's was due to accidental 
cross-pollination. Fletcher states that in crossing yellow-flowered with white-flowered 
varieties he found yellow to be completely dominant. 
Fyson (20), crossing a yellow-flowered with a white-flowered Indian cotton, also 
reported complete dominance of the yellow color in F, . The segregation in F 2 was 
not fully worked out, but taking all progenies as one array, 729 individuals were 
classed as yellow, 156 as "pale," and 411 as white, a distribution which arouses the 
suspicion that either the classing was faulty or much accidental cross-pollination had 
occurred. F 5 progenies of yellow-flowered F 4 individuals were uniformly yellow in 
some cases, while in other cases segregation in a ratio of approximately three yellow 
to one white was recorded. Progenies of white-flowered F 4 individuals were white 
flowered, with a few exceptions attributed by the author to accidental cross- 
pollination. 
Balls (4, pp. 36, 37) found that in a hybrid of upland with Egyptian cotton petal 
color was intermediate, or "lemon," in F 1} while two second-generation progenies 
were classified as 16, 36, 17 and 21, 51, 23 yellow, intermediate, and white, respectively, 
these figures indicating a 1 : 2 : 1 ratio. F 3 progenies of some of the F 2 individuals 
were grown, but the populations were far too small to give trustworthy data. In a 
later publication by the same author (6. pp. 134-138) it is suggested that in the petal 
color of upland -Egyptian hybrids "not less than three pairs of allelomorphs may be 
involved." It is stated also that Fj is always intermediate and that white-flowered 
F 2 individuals always breed true while yellow-flowered F 2 individuals breed true in 
some cases but segregate in others. Balls points out that in the second genera! ion 
there is always an excess of the paler shades, as was found by the writer to be the 
case in the Holdon-Pima hybrid. 
Leake (31, pp. 212, 213, and Table 1, p. 244) reported that in a hybrid between a 
yellow-flowered and a white-flowered Indian cotton F x was "all vellow flowered." 
in an P 2 population of 161 individuals the ratio of yellow flowered to white flowered 
was 2.1 to 1. Progenies of white-flowered F a individuals bred true, while the prog- 
enies of yellow-flowered F 2 gave the following data: 5 F 3 progenies (aa one array) 
65 yellow, white; 6 F 3 progenies (as one array) 34 yellow, 11 white. The author 
suggests that the excess of white-flowered individuals in F. : , which gave a 2 to 1 
rather than a 3 to 1 ratio, may be correlated with the fact thai in India wnite-flowered 
races are always the hardier. 
42433—23 5 
