*.. IQ] HARRIS AND OTHERS SEEDLINGS OF PHASEOLUS JI 



\Ye shall consider in order the levels at which sections were made, begin- 

 ing at the root. 



i. Root. Roots were sectioned in the cases of lines 93, 139, and 143. 

 &quot;he numbers of bundles 7 in the roots of normal and trimerous seedlings of 

 lines are shown in table I . 



TABLE i 



The entries in this table show that most of the normal plants are tetrarch, 

 Ithough a small percentage are pentarch. In the trimerous seedlings the 

 ighest percentage are pentarch. but the remainder are distributed between 

 etrarch and hexarch with a few in more extreme classes. Sections made at 

 ogressively lower levels in the root show that the hexarch and pentarch 

 auditions, in the trimerous seedlings, soon give way to tetrarch. This 

 act doubtless explains the relatively large number of non-hexarch cases 



CABLE 2. Vascular formula for base of kypocotyl of trimerous seedlings and their normal 



controls 



7 Where the bundles were united in a ring, the number refers to number of protoxylem 



r.n-- = 



