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EDMUND W. SINNOTT 
suggested by the fact that in the mature plant the topography of the 
node, with the number and arrangement of leaf traces and gaps, has 
been shown (2) to be very constant throughout wide groups. To 
determine whether or not the characters of the cotyledonary node 
Fig. 2. Momordica Balsamina (Cucurbitaceae). Serial sections from root to 
cotyledon, a, root; h-d, hypocotyl; e-g, node (showing relation of cotyledonary 
bundles to those of epicotyl); h, epicotyl and cotyledons. (Xylem black, phloem 
white.) 
are also slow to change, careful attention was given not only to the 
vascular supply of the seedling proper, consisting of the cotyledonary 
traces and their extensions into the hypocotyl, but to the relation 
between these first strands and those which arise later and form the 
vascular system of the epicotyl and subsequently the stem of the 
young plant. It was found that this relationship between the hypo- 
cotyledonary and the epicotyledonary systems, a feature hitherto 
neglected, provides some of the most constant structural characters 
of the seedling. 
