333 
Anatomy of Ter at o logical Seedlings. III. 
members, and it is of interest to note that the hypocotyledonary adventitious 
roots which characterize this plant, and which arise from the protoxylems, 
also develop in two vertical series instead of the usual four (Fig. 3i a). 
Starting from this basal type there has been a progressive elaboration of the 
Figs. 63-77. Figs. 63-69, simple type of Group II seedling, the cotyledon showing the structure 
of a single normal cotyledon and developing a diarch root-plate. Figs. 70-77, Group II seedling 
showing on the left delayed fusion of lateral and marginal bundles and on the right independence of 
the two. 
lateral vascular system. This seems to be due in a measure to an increase 
in the relative importance of the marginal veins from the lamina, which, 
instead of uniting with the laterals at the distal end of the cotyledonary 
petiole, show a progressively delayed fusion until in many cases they only 
unite near the apex of the hypocotyl. This delay in fusion has inevitably 
