340 
Holden. — Observations on the 
these bundles unite to form two groups which become widely separated and 
ultimately unite with the lateral bundles of the normal cotyledon, thus pro- 
ducing an asymmetrically triarch condition of the hypocotyl which is 
reflected in the development of three members only in the root whorl 
(Figs. 110-113). Below the point of origin of these roots the main root is 
tetrarch as in normal dicotyls. We have evidently to deal in this instance 
with a cotyledon in which the midrib is entirely lacking, its place being 
taken, in the lamina and petiole, by one of the laterals. With regard to the 
epicotyl this is chiefly remarkable from the fact that a whorl of three 
Figs. 107-113. Transverse sections of seedling with two unequal cotyledons (Fig. 8), showing 
suppression of the median double bundle in one cotyledon and the developmen of asymmetrical 
triarchy in the hypocotyl. Ri, Rii, r iii, lateral roots; AX., tetrarch axis. 
leaves is produced at the second epicotyledonary node instead of the usual 
pair. The resultant modification in the grouping of the foliar traces in the 
epicotyl is indicated in Figs. 44-48. It is noteworthy that one of the 
compound epicotyledonary bundles (Fig. 109, <3 ) is interposed between, and 
unites with, the approaching cotyledonary laterals on the same side, and that 
towards the base of the epicotyl the remaining strands form a shallow open 
gutter in the intercotyledonary plane. 
The positive evidence in support of the origin of the second group of 
seedlings by syncotyly rests chiefly on the leaf position and the type of 
modification found in the epicotyl. The first epicotyledonary leaf stands in 
the position normally occupied by the second cotyledon, and if the cotyledon 
