220 BOTANICAL GAZETTE [September 



Fig. 19. — Longitudinal section of lower part of embryo emerging from 

 seed. X8. 



Fig. 20. — Transverse section of the vascular plate of hypocotyl. X225. 



Fig. 21. — Diagram representing rise of cotyledonary bundles from vascular 

 plate. 



Fig. 22. — Diagram showing origin and course of first leaf traces. 



Fig. 23. — Diagram showing origin and behavior of traces of second leaf. 



Fig. 24.— Horizontal diagram of cotyledonary node. 



Fig. 25. — Same node in plants developed on clinostat. 



Fig. 26. — Transverse section slightly above cotyledonary node showing the 

 four main cotyledonary bundles and the three groups of foliar bundles. X60. 



Fig. 27. — Longitudinal section of embryo somewhat less developed than the 

 one represented in fig. ig. Xio. 



Fig. 28. — Transverse section of stele of hypocotyl 2 mm above the section 

 represented in fig. 20. X225. 



Fig. 29. — Transverse section of stele of hypocotyl immediately below coty- 

 ledonary node. X225. 



Fig. 30. — Transverse section of plant with median bundle of aborted cotyle- 

 don fairly well developed. Same level as fig. 26. X8. 



Fig. 31. — Section of same plant 140 m above that represented in fig. 30. X8. 



Fig. 32. — Detail of portion of axis o.2 mm below fig. 30, between the cotyle- 

 donary bundle B and the phellogen; shows group of cambium cells which gave 

 rise to anomalous strand z. X75. 



Fig. 33.— Transverse section of the anomalous strand represented in base 

 of cotyledon in fig. 30. X135. 



Fig. 34. — Cotyledonary node of plant with median bundle of aborted cotyle- 

 don well developed. X150. 



Fig. 35. — Stele of hypocotyl o.36 mm below fig. 34; xylem and phloem 

 collected in ring. X150. 



Fig. 36. — Section of stele of same plant o . i6 mm below ^g. 35; shows breaking 

 apart of phloem opposite the protoxylem. X 150. 



Fig. 37. — Same, o.2 mm below the previous section; separation of metaxylem. 

 X150. 



Fig. 38. — Section of root stele between the third and fourth whorls of lateral 

 roots. X179. 



Fig. 39. — Section of stele near root tip at beginning of differentiation 

 of xylem. X225. 



Fig. 40. — Transverse section of stele of lateral root showing exit of a tertiary 

 root. X225. 



Fig. 41. — Longitudinal section of seedling showing beginning of root forma- 

 tion. Xio. 



Fig. 42. — Detail of beginning of root formation. X60. 

 Fig. 43. — Detail showing interruption between vascular tissues of hypocotyl 

 and root. X120. 



