30 BULLETIN 1164, U. S. DEPARTMENT OF AGRICULTURE. 
Two crosses made by Leake between Indian cottons having, respectively, deep- 
yellow and pale-yellow petals are reported (31, p. 213) to have shown full dominance 
of the deep yellow in P lt The numbers of deep yellow and of pale yellow in F 2 
indicate ratios of 2.4 to 1 and 1.4 to 1, respectively. The author remarks that these 
cases of petal color were the only ones "in which complete dominance has been 
observed in the cottons under consideration." 21 
Leake reports (31, pp. 241, 242) a correlation, to which he says no exception has 
been found, between size and color of petal, white petals being always much smaller 
than yellow petals. It is interesting to note in this connection that in the second 
generation of the Holdon-Pima hybrid the coefficient of correlation for corolla length 
and petal color was 0.214 ±0.048, indicating that there is a tendency for long petals to 
be associated with pronounced yellow color and vice versa. Individual cases occur- 
red, however, in which large corollas wore very light colored and small corollas were 
deep yellow, and these combinations persisted in F 3 . 
That red color in the vegetative organs and in the petals may be dependent upon 
the same factor is indicated by data recorded by Leake for Indian cottons. When a 
red-leafed, red-flowered type was crossed with a green-leafed, yellow-flowered type 
(31, pp. 216, 217) there was partial dominance of red in both organs in F t and a 3 to 
1 ratio in F 2 for presence contrasted with absence of red. Crossing a red-leafed, red- 
flowered type with a green-leafed, white-flowered type (31, pp. 217, 218, Table 7, 
p. 247, pi. 35), 22 he found that in F t there was partial dominance of the red in both 
organs, but the petals of the first-generation flowers were red and yellow, rather than 
red and white. 
In F 2 six types were obtained, in the following proportions : 
Number. 
Petals red, leaf all red 89 
Petals red and yellow, leaf veins red 193 
Petals red and white, leaf all. red 30 
Petals red and white, leaf veins red 78 
Petals yellow, leaf green 96 
Petals white, leaf green 25 
The ratio is therefore approximately 3:6:1:2:3:1. The data from F 3 progenies of 
individuals representing all six types in F 2 conformed remarkably well to the expecta- 
tion. Leake interprets these results as attributable to the presence in the red-leafed 
parent of a factor for red color in the leaf and the petal which is dominant in respect 
to its absence and of a factor for yellow color in the petals which is also dominant to its 
absence, the green-leafed, white flowered parent having carried the recessive factors 
for both colors. The results indicate, although it is not expressly so stated, that both 
dominant factors (R and Y) must be present, the former in double dose, in order to 
produce a solidly red-colored petal. 23 
McLendon (34, pp. 191-198) reported that in hybrids of sea-island cotton with 
upland varieties, F x was intermediate in petal color. The data as presented 
indicate that in F 2 the full yellow color of the sea-island parent was not recovered 
and that a much greater number of individuals had intermediate colored (pale yellow) 
petals than white petals. 
Harland (22) describes crosses among types of cotton grown in the West Indies 
representing six different grades of petal color, from white (pale cream) to a pronounced 
yellow. " A cross between any two of the above shades gave an intermediate F x . 
In all F a families the parental and F { color types appeared, but there may have been 
other intermediate color forms " (p. 15). In a cross of white with yellow of grade 3, 
the F 2 ratio appeared to be 4.4 yellow to 1 white. In progenies of eight yellow- 
flowered F 2 individuals only yellow flowers appeared in F 3 . Progenies of 27 other 
yellow-flowered F 2 's contained both yellow and white flowered individuals, the totals 
for all heterozygous progenies as one array having been 477 yellow and 180 white. 
The departure from a 3 to 1 ratio is not significant. Progenies also were grown of 11 
white-flowered F 2 individuals, of which 6 bred true, while 5 progenies, taken as one 
array, comprised 150 white-flowered and 11 yellow-flowered plants, the occurrence of 
the latter, in Harland's opinion, being attributable to accidental cross-pollination. 
* L In a later publication (.32, p. 126) it is stated that "yellow is dominant both to pale yellow and to 
white." This was not the case in the upland-Egyptian cotton hybrids studied by Balls and by the writer. 
"This cross is further discussed and illustrated by Leake and Prasad (32, pp. 128-132, pis. 14-18). 
"Reference to Leake's table 7 shows that the departure from a 9:3 :3 : 1 ratio is not very great if the 
classes are arranged as follows: Containing both R and Y, 282 individuals; containing R but not Y, 108 
individuals; containing Y but not R, 96 individuals; containing neither R nor Y, 25 individuals. 
Compare also Leake and Prasad, 32, p. 131. 
