b., 1921] 



HARRIS AND OTHERS SEEDLINGS OF PHASEOLUS 



Trimerous Seedlings 



Dimerous Seedlings 



With the exception of the dimerous seedlings of line 139, the actually 

 bserved 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- 

 terous seedlings. Thus in the dimerous class about 40 percent of the 

 jedlings show a number of bundles in the central region of the hypocotyl 

 hich is in excess of twice the number of primary double bundles plus the 

 umber of intercalary bundles at the base of the hypocotyl. In the case 

 f the trimerous seedlings the excess is much smaller, being roughly 20 

 ercent. Thus it is clear that, especially in the normal seedlings, a large 

 umber of the intercalary bundles do not extend to the base but appear in 

 le axis, ending blindly below, or that a considerable proportion of the 

 rimary double bundles divide into more than two bundles. 



In line 143 the number of cases in which the observed number of bundles 

 ; greater than the calculated number is much more nearly equal in the two 

 ypes of seedlings. Thus in the trimerous seedlings 24.4 percent of the 

 sedlings have a number of bundles in the central region of the hypocotyl 

 reater than 2p + i, whereas in the dimerous seedlings there are 18.1 per- 

 ent of seedlings of this class. In line 139 only 0.7 percent of the dimerous 

 eedlings show a number of bundles in excess of 2p + i, whereas in the 

 rimerous seedlings 12.3 percent are in excess. 



Thus lines 139 and 143 give results diametrically opposed to those of 

 he first three discussed. 10 



Summary for Central Region of Hypocotyl. It is evident from the 

 bove statements that the number of bundles in the hypocotyl of trimerous 

 5 decidedly higher than in that of dimerous seedlings; that in general the 

 lundle number is more variable in dimerous than in trimerous seedlings; 

 nd that the intercalary bundles generally extend to a lower level in the 

 typocotyl of trimerous than in that of dimerous seedlings. 



10 Note that the extremely small excess in line 139 may be due to the extraordinarily 

 ormal character of the vascular system of the dimerous plants of this line. 



