CHARACTERS IN AN UPLAXD-EGYPTIAX COTTON HYBRID. 7 
the category of intensified size characters. These were a slight crink- 
liness of the leaf margins (PL IV), a character much more fully 
developed in many of the F 2 plants, and bright-green color of the fuzz 
on most of the seeds. The prevailing color of the fuzz in the Pima 
parent is also green, but of a duller shade than in F v This peculiarity 
of first-generation hybrids between upland and Egyptian or sea-island 
cottons has been noticed by Cook (10). 8 
DEFINITION OF THE CHARACTERS MEASURED OR GRADED. 
The descriptive list which follows comprises the characters which 
were determined, by measurement or grading, on the parental and the 
hybrid F 2 progenies grown in 1919 and on the hybrid ¥ 1 progeny 
grown in 1920. Some of these characters were determined also on 
the parental and hybrid F x progenies grown in 1917 and 1918 and on 
the F 3 progenies in 1920. Holdon and Pima are distinguished by 
numerous other characters, some of them indicated in the foregoing 
botanical descriptions, which could not be measured or graded with 
accuracy in F 2 . Examples of such characters are color of the leaf, 
smoothness of the boll surface, and color of the fuzz on the seed. 
All measurements were made in the field except that certain boll 
characters were measured on natural-size photographs. The measure- 
ments were made on one fruiting branch, one leaf, one flower, and one 
boll on each plant. Of the graded characters, those of the leaf were 
determined in the field and those of the bracts and flowers in the 
laboratory on freshly gathered material. All fiber and seed charac- 
ters were measured or graded in the laboratory. 
Axis length was measured in centimeters on the main stem from the surface of the 
ground (approximate level of the cotyledon node) to the terminal bud. Of the 
parental populations, Pima gave the higher mean for axis length. 
t Axis internode length is the average length, in millimeters, as determined by 
dividing the axis length by the number of internodes. The mean internode length 
was higher in Pima than in Holdon. 
Axis internode number includes all internodes above the cotyledon node up to and 
including the highest one which had reached a length of about 15 millimeters. The 
mean internode number was higher in Pima than in Holdon. 
Fruiting branch length, in centimeters. The longest fruiting branch on each plant 
was measured. The determination of this character on some half dozen of the F 2 
hybrid plants was rendered difficult by the absence of a sharp distinction at relatively 
high nodes between vegetative branches and fruiting branches, all possible inter- 
gradations having existed. In such cases measurement was made of the longest 
branch above the zone of typical vegetative branches which had an approximately 
horizontal position. The fruiting branches of Pima averaged longer than those of 
Holdon. 
Fruiting branch first internode length, in centimeters, was measured on the same 
branch of which the total length was determined. Pima exceeded Holdon in the 
mean for this character. 
Leaf length (fig. 1, a b), in millimeters, was measured from the base of the blade to 
the apex of the terminal lobe. Pima gave a higher mean for leaf length than Holdon. 
Leeif width (fig. ] , c d), in millimeters, was measured from tip to tip of the principal 
lateral lobes. Pima gave a higher mean than Holdon for this character. 
Leaf index, leaf width as a percentage of the length. A relatively broad leaf has 
a high leaf index and vice versa. The mean leaf index was higher in Pima than in 
Holdon. 
Leaf lobe index, the distance from the base of the blade to the bottom of the sinus 
between the terminal lobe and the upper right-hand lateral lobe (fig. 1, a e), expressed 
8 Extraparental characters appearing in the first generation of a hybrid between sea island nnd a 
cotton native to St. Croix, the* latter belonging apparently to the upland series, are mentioned by 
Harland (f/,p.54). 
