Nov., 1921] HARRIS AND OTHERS — PHASEOLUS VULGARIS 
and the deviation of the number of intercalary bundles, i, from their prob- 
able value by the formula^ 
^ rbi - ri/rj 
where z = i — J-h, 
b 
we have the values given in table 3. 
Table 3. Correlation between Total Bundles at Base of Hypocotyl and Deviation of Number 
of Intercalary Bundles from Their Probable Number 
Line 
Trimerous 
Dimerous 
Difference 
Diff. 
N 
r 
r 
Er 
N 
r 
r 
Er 
75 
142 
.7643^-0235 
32.5 
142 
.85i3±.oi56 
54-6 
— .o870zb.o283 
3.07 
93 
155 
.6787^1.0292 
23.2 
155 
.6693 zt. 0299 
22.4 
+.0094 ±.0412 
0.22 
98 
183 
.7944±-Oi84 
43-2 
183 
.8433±.oi44 
58.6 
— .0489^.0224 
2.18 
139 
106 
.4066^.0546 
7-45 
305 
.9701 ±.0023 
421.8 
-.5636^0.540 
10.3 
143 
221 
.3841^.0386 
9-95 
420 
.85iodb.oo90 
94.6 
— .4669d=03.96 
11.8 
The coefficients are positive and high, and very consistent for the two 
types of seedlings. They show that within one morphological type of 
seedling^ an increase in the total number of bundles is primarily due to the 
formation of intercalary bundles, rather than to variation in the number of 
primary double bundles, although both types of bundles contribute to the 
end result. 
Summary 
An investigation of the interrelationship of the numbers of primary 
double bundles, intercalary bundles, and total bundles (primary double 
bundles plus intercalary bundles) at the base of the hypocotyl in dimerous 
and trimerous seedlings of Phaseolus vulgaris leads to the following results: 
I. In the trimerous seedlings there is a negative correlation of about 
medium value (r = —.5 dr) between the number of primary double bundles 
and the number of intercalary bundles. Thus the number of intercalary 
bundles is smaller in seedlings with larger numbers of primary double 
bundles and vice versa. In dimerous seedlings the correlation is perhaps 
also negative in sign, but practically zero numerically. 
^ Harris, J. Arthur. The correlation between a variable and the deviation of a de- 
pendent variable from its probable value. Biometrika 6: 438-443. 1909; also, Further 
illustrations of the applicability of a coefficient measuring the correlation between a variable 
and the deviation of a dependent variable from its probable value. Genetics 3: 328-352. 
1918. 
^ The differentiation of trimerous and dimerous seedlings has been shown to be due 
primarily to an increase in the number of primary double bundles. 
