.. 1921] 



HARRIS AND OTHERS PHASEOLUS VULGARIS 



431 



:nd the deviation of the number of intercalary bundles, i, from their prob- 

 ble value by the formula 5 



where s = i --b, 



b 

 Ire have the values given in table 3. 



LIABLE 3. Correlation between Total Bundles at Base of Hypocotyl and Deviation of Number 

 of Intercalary Bundles from Their Probable Number 



The coefficients are positive and high, and very consistent for the two 

 :ypes of seedlings. They show that within one morphological type of 

 seedling 6 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 Phaseohis vulgaris leads to the following results: 



i. In the trimerous seedlings there is a negative correlation of about 

 ;medium value (r = .5 ) 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. 



6 Harris, ]. 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. 



6 The differentiation of trimerous and dimerous seedlings has been shown to be due 

 primarily to an increase in the number of primary double bundles. 



