236 
Journal of Agricultural Research 
Vol. XXI, No. 4 
In 1915 the two strains, as represented by progeny groups 5-3-10 and 
5~ I 3“'7> were further compared in regard to length of axis and develop¬ 
ment of the vegetative branches, with the results given in Table IV. 
TABLE IV.— Means for axis length and limb index in two lines of the Pima variety grown 
in 1915 
Character. 
Group 5-3-10 
(25 plants). 
Group 5-13-7 
(15 plants). 
Differences 
between means. 
Axis length (cm.). 
I48± i. 28 
H 5 ±I 2 . 30 
1761k 2. 96 
I44±I2. 56 
28ik 3. 23 
291k 17. 60 
Limb index. 
The differences in the means for axis length and limb index are in the 
same direction as those for strains 5-3 and 5-13 in 1914, but the differ¬ 
ence in limb index in 1915 was less than twice its probable error. This 
character, however, is extremely sensitive to environmental influence, 
and it is a fair assumption that the two strains are genetically different 
in respect to both the length of the axis and the development of the 
vegetative branches. 
The records for 1914 permit comparison of still more closely related 
lines. In that year progenies were grown of several plants which had 
been selected in progeny 5-3 of 1913. One of these progenies (5-3-4) 
was noted as being very uniform and very distinct from the others, the 
plants having been stiff and open looking, with long fruiting branches, 
long internodes of the axis and fruiting branches, and rather stiff leaves 
which were deeply and narrowly lobed. This description recalls the 
“bull-stalk’’ type which was encountered frequently in roguing the seed- 
increase fields, except that the plants were not noticeably taller than in 
the other progenies. The differences in stem and branch characters, as 
compared with the progeny of a sister plant (5-3-10), are shown by the 
data in Table V. 
Table V .—Means for stem and branch characters of two progenies from sister plants, 
grown in 1914 
Character. 
Progeny 5-3-4 
(12 plants). 
Progeny 5-3-10 
(11 plants). 
Differences in 
the means. 
Axis length (cm.). 
183. oil. 80 
38.oi .25 
48.2± .35 
63.2 i 1.19 
I79.0i2.i9 
41.2i .39 
43 - 5 ± -66 
56. 5 ± -78 
4.oi2.83 
3- 2i .46 
4 - 7 ± -75 
6.7 i 1.42 
Axis internode number. 
Axis intemode length (cm.). 
Fruiting branch length (cm.). 
0 O \ •/ . 
Progeny 5-3-4 had significantly fewer and significantly longer inter¬ 
nodes of the axis and significantly longer fruiting branches than progeny 
5-3-10, the differences having been, respectively, 6.9, 6.3, and 4.7 times 
their probable errors. 
