June 9, 1923 
Rogue Types in Garden Peas 
829 
F^om seeds of 25 Fj hybrids, 742 Fg hybrids were matured in 1920. A total of 708 
individuals, belonging to 23 families, were classified according to stipule shape as 
Graduslike types (yy) and intermediates (YY or yy), the latter class being made up 
of plants resembling Mummy in stipule character, ^e remaining families, consist¬ 
ing of 34 plants, were not directly classified in the same way, but the mean stipule 
ratio per plant was calculated from measurements of the width and length of the 
stipules. A record of the flower color was kept for all the 742 F2 plants (Tables VIII 
and IX). 
Of the 708 plants classified according to stipule shape, 540 were grouped as inter¬ 
mediates resembling Mummy and 168 as Graduslike types (Table X), indicating a 
single factor difference, in regard to stipule shape, between Gradus type and Mummy. 
The expected percentage in the two groups is 75 per cent intermediates and 25 per 
cent types; the observed percentages, 76.27 per cent intermediates and 23.73 per cent 
Graduslike types, in the Fg, are well within the limits of the standard error. The 
standard error as used here is calculated according to the formula of Yule {16). 
TabIv^ X .—Segregation of stipule shape in generation of Gradusy^Mummy (yyXYY) 
GRADUS X MUMMY 
YY, Yy 
yy 
Total. 
Observed. 
540 
76.27 
75.00 
1.27 
1.09 
I.16 
168 
23-73 
25.00 
1.27 
708 
Percentage found. 
Percentage expected.. 
Difference (D). 
Standard error (S. E.). 
D/S.E. 
RELATION OP Y AND y, FACTORS POR STIPULE SHAPE 
In all, 37 Fi plants were grown in 1919 from the cross Gradus type 
with Mummy. In size and shape the stipules of the plants were 
intermediate between Mummy and Gradus type. The upper part of a 
branch of a mature P^ plant is shown in Plate 3, A. 
LINKAGE RELATION OP Yy AND Aa 
The relation of the factor pairs Yy and Aa was determined from 
a count of 708 Pj plants of the cross Gradus type with Mummy 
(aayyXAAYY). In Table XI are tabulated the observed numbers of 
the P2 recombinations. The actual ratios of the four classes AY, aY, 
Ay, and ay indicate that factors AY and ay are linked. The calculated 
zygotic series is approximately 66 AY : 9 Ay : 9 aY : 16 ay; the gametic 
series approximately 4:1 : : i 14; and the percentage of crossing-over 
for all the Pj families is 20.41 ±1.28 per cent, using Haldane’s method (d) 
for the determining of zygotic and gametic series from observed P2 
frequencies. 
Table XI .—Linkage relation of Aa and Yy from F2 generation of Mummy X Gradus 
aayyXAAYY. 
AY. 
Ay. 
aY. 
ay. 
Total. 
Observed. 
476 
467 
9 
63 
64 
I 
64 
64 
0 
105 
I13 
8 
708 
Calculated. 
Difference. 
— a.'7 CCA . 
A . 
