May 16, 1921 
Heritable Variations in Cotton 
229 
of the 32 plants of the Pima parent progeny. 1 The progeny grown in 
1920 showed considerable variation in this character, but a majority of 
the plants had smoother seeds than the average Pima and a few indi¬ 
viduals had almost naked seeds. It is therefore probable that plant 
No. 28 was a first-generation Pima X Yuma hybrid, the original Pima 
plant of 1910 having been surrounded by plants of the Yuma variety. 
It is surprising, under the circumstances, that in a progeny of 32 indi¬ 
viduals only 1 showed recognizable Yuma characters. 2 
In order to measure the degree of change which might have taken 
place as a result of several years of selection in the Pima variety, the 
progeny of the parent plant grown in 1919 was compared with an equal 
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Fig. i.—P edigree of progenies, progeny groups, and strains of the Pima variety of American Egyptian 
cotton. Each progeny is from an individual plant selection of the preceding year. As here used, the term 
“progeny group” comprises the progenies of sister plants of the preceding year and the term “strain” com¬ 
prises all lines derived from the same progeny group. 
number of plants taken at random in the commercial stock of strain 5-3 
and of two progenies (YiA and Y2A) derived from the same strain by 
five generations of controlled self-fertilization. The ancestry of these 
selfed lines is indicated in figure 1. For the sake of brevity, the three 
populations will be referred to hereafter as “parent progeny,” “5-3 
bulk,” and “5-3 selfed.” All were grown under conditions of soil, 
irrigation, and spacing which were as nearly as practicable identical. 
1 The apparent dominance of a less fuzzy over a more fuzzy condition of the seed coat in this presumable 
first-generation hybrid is exceptional, since according to Balls (Balls, W. Lawrence, some cytological 
aspects of cotton-breeding. /» Amer. Breeders’ Assoc. Rpt. 1908, v. 5, p. 18. 1909.) “little fuzz" is 
dominant over “no fuzz” and “entire fuzz” is dominant over “little or no fuzz”. Similar relations are 
reported by McLendon (McLendon, C. A. mendElian inheritance in cotton hybrids. Ga. Agr. Exp. 
Sta. Bui. 99, p. 169. 1912.). It has been the writer’s experience that in hybrids between Egyptian 
varieties with partly fuzzy seeds and Upland varieties with completely fuzzy seeds the first generation 
has completely fuzzy seeds. 
2 Progenies comprising from 22 to 34 individuals were grown in 1920 from selfed seed of 5 plants of the 
“parent” progeny of 1919, and the leaf and boll characters listed in Table I were determined for all plants 
of each progeny. Comparison of the means of these progenies with the means of selfed and open-pollinated 
stocks of strain 5-3 showed no important differences, except that the mean boll diameter and boll index 
(diameter as a percentage of the length) of the progeny of plant 28 were significantly smaller than in any 
other progeny or strain of Pima on which these characters were measured in 1920. Comparison of the 
coefficients of variation for the several characters showed that progeny 28 was decidedly more variable 
than the other granddaughter progenies of the parent Pima plant, as would be expected if this progeny 
represented the second generation of a Pima X Yuma cross. 
