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EDMUND W. SINNOTT 
cotyledonary poles, separating the adjacent laterals. Sometimes, as 
in Ricinus, epicotyledonary bundles may also appear between the two 
central strands of the trace, thus causing each trace to leave four 
gaps in the vascular ring. Sometimes, as in certain of the Euphorbi- 
aceae, Aceraceae and Proteaceae (Fig. 4, /), the cotyledonary trace 
Fig. 4. Diagrams showing cross-sections of node, course of bundles in base 
of one cotyledon, and section of cotyledon, in six seedling types, a, Ephedra dioica, 
gymnospermous type, unilacunar, two trace bundles, no midrib; h, Thespesia 
populnea, unilacunar, two trace bundles, giving rise to three-veined condition; 
c, Lavatera arhorea, unilacunar, four trace bundles fusing into two and then producing 
three-veined cotyledon; d, Momordica Balsamina, unilacunar, four trace bundles 
forming three-veined condition directly; e, Echinops sphaerocephalus, trilacunar, 
four trace bundles, forming three-veined cotyledon; /, Grevillea rohusta, bilacunar, 
two trace bundles, forming three-veined cotyledon. (Leaf traces black in section, 
epicotyl bundles white.) 
may consist of only two strands, but these may be separated by epi- 
cotyledonary bundles, a bilacunar node thus being produced. In all 
these cases the essential fact is that the node is multilacunar, the 
