r., 1921] HARRIS AND OTHERS PHASEOLUS VULGARIS 427 



Dimerous Trimerous 



Line 75: P = 4.255 - 0.058 / P = 6.059 - 0.318 / 



/ = 1.641 - 0.239 P / = 4.968 0.789 P 



Line 93: P = 4.607 o.uo / P = 5.992 0.448 / 



/ = 1.398 0.127 P I = 5.200 0.846 P 



Line 98: P = 4.099 + 0.035 I p = 5-9 8 4 -39 2 I 



I = 0.114 + 0.117 P / = 6.559 1.084 P 



Line 139: P = 4.005 + 0.034 / P = 5-95 - 0.558 / 



/ = ._ 2.038 + 0.541 P / = 2.795 - 0.457 P 



Line 143: P = 4.060 + 0.019 / P = 5.924 0.408 / 



/ = 0.047 + 0.059 P I = I-73 2 - 0.249 P 



The mean number of intercalary bundles associated with given numbers 

 ^f primary double bundles and the theoretical means as given by the 

 Degression straight lines are shown on diagram I. 



For the normal plants of lines 75, 93, and 139 the agreement between 

 ihe observed means and the regression line is very satisfactory. In line 

 1)8 a single seedling with 8 primary double bundles and 4 intercalary bundles 

 Hves a positive sign to the correlation and makes the agreement of theo 

 retical and empirical means very poor indeed. In lines 139 and 143 the 

 correlation is also positive. It must be noted that we are dealing here 

 Ivith a very narrow range of both primary double bundles and intercalary 

 )undles, and with very small frequencies in some of the classes. 



For the abnormal plants the agreement of empirical means and theo- 

 etical lines is apparently very poor indeed. This is perhaps largely attrib 

 utable to two facts: 



(a) The frequencies of primary double bundles are, practically speaking, 

 concentrated in two classes, 5 and 6 bundles. From 93 to 99 percent of the 

 seedlings fall in these two classes. As a result of this condition, the ob- 

 :aining of trustworthy averages for the extreme classes of primary double 

 Bundles is, practically speaking, impossible. 



(b) The influence of the two principal classes (5 and 6) of primary 

 double bundles is such as to throw the theoretical mean number of interca 

 lary bundles for higher classes of primary double bundles on the negative 

 side of o in four of the five cases. 



As a consequence, the actual mean number of intercalary bundles must 

 lie above the line in all cases in which more than 6 primary double bundles 

 are formed. 



Whether these irregularities represent a significant deviation from line 

 arity can be determined only when far larger series of data are available. 



While the primary double bundles must probably be regarded as more 

 fundamental structures than the intercalary bundles, it seems of interest to 

 determine the mean number of primary double bundles associated with each 

 number of intercalary bundles. 



