Feb., I92i] HARRIS AND OTHERS — SEEDLINGS OF PHASEOLUS 9I 
Trimerous Seedlings 
N 
In Defect 
2/ + i 
In Excess 
Line 75 
142 
7.0 
76.1 
16.9 
Line 93 
1-3 
78.1 
20.7 
Line 98 
183 
3-3 
86.3 
10.4 
Line 139 
106 
7.6 
80.2 
12.3 
Line 143 
221 
0.9 
74-7 
24.4 
Dimerous Seedlings 
N 
In Defect 
2/ + / 
In Excess 
Line 75 
142 
2.1 
514 
46.5 
Line 93 
1.9 
47.7 
50.3 
Line 98 
183 
3.8 
59.0 
37.2 
Line 139 
0.7 
98.7 
0.7 
Line 143 
221 
0.9 
81.0 
I8.I 
With the exception of the dimerous seedlings of Hne 139, the actually 
observed number of bundles is in excess of the number given by the formula. 
In lines 75, 93, and 98 the excess is far greater in dimerous than in tri- 
merous seedlings. Thus in the dimerous class about 40 percent of the 
seedlings show a number of bundles in the central region of the hypocotyl 
which is in excess of twice the number of primary double bundles plus the 
number of intercalary bundles at the base of the hypocotyl. In the case 
of the trimerous seedlings the excess is much smaller, being roughly 20 
percent. Thus it is clear that, especially in the normal seedlings, a large 
number of the intercalary bundles do not extend to the base but appear in 
the axis, ending blindly below, or that a considerable proportion of the 
primary double bundles divide into more than two bundles. 
In line 143 the number of cases in which the observed number of bundles 
is greater than the calculated number is much more nearly equal in the two 
types of seedlings. Thus in the trimerous seedlings 24.4 percent of the 
seedlings have a number of bundles in the central region of the hypocotyl 
greater than 2p + i, whereas in the dimerous seedlings there are 18.1 per- 
cent of seedlings of this class. In line 139 only 0.7 percent of the dimerous 
seedlings show a number of bundles in excess of 2p + i, whereas in the 
trimerous seedlings 12.3 percent are in excess. 
Thus lines 139 and 143 give results diametrically opposed to those of 
the first three discussed. 
Summary for Central Region of Hypocotyl. It is evident from the 
above statements that the number of bundles in the hypocotyl of trimerous 
is decidedly higher than in that of dimerous seedlings; that in general the 
bundle number is more variable in dimerous than in trimerous seedlings; 
and that the intercalary bundles generally extend to a lower level in the 
hypocotyl of trimerous than in that of dimerous seedlings. 
Note that the extremely small excess in line 139 may be due to the extraordinarily 
normal character of the vascular system of the dimerous plants of this line. 
