LIST OF ILLUSTRATIONS AND EXPLANATION OF PLATES. 53 



PLATE i%, continued: 



93-96. Diagrams of successive cross-sections of petiolar bundle giving off a leaf- 

 shoot bundle. Conventional signs as in figs. 83-87; /, leaf-shoot. 



97. Diagrammatic cross-section of leaf-shoot, near its origin. Conventional signs as 



m figs. 88-92; 2 indicates part drawn in fig. 63 



98. Isolated tracheids of fork of stem. 



99. Diagram of fork of stem, longitudinal section. Conventional signs as in figs. 



83-87. 



100. Diagrammatic cross-section of node; stem to right. Conventional signs as in 



figs. 83-87. 



101. Diagrammatic transverse section of base of petiole. Conventional signs as in 



figs. 88-93; a, region of stomata. 



102. Diagram of junction of root and stem, longitudinal section. Cortex and 



medulla section-lined. 

 PLATE 13: 



103. Stem-initial with four segments, in transverse section, with leaf-rudiment, d, at 



left. X 210. 



104. Transverse section of stoma. After Copeland, 1902. 



105. Glandular hair of leaf, with two gland-cells. X 210. 



106. Longitudinal section of stem apex; heavy lines at right show boundary of 



vascular bundle; d, intercalary growth of hair; u, origin of hair. 

 Composite. X 210. 



107. Protophloem in transverse section of stem near apex. X 210. 



108. Transverse section of stem-bundle at margin of leaf-gap, showing continuity of 



inner and outer vascular tissues. X 210. 



109. Oblique transverse section of stem-initial, with leaf-rudiment (b) in fourth 



segment. X 360. 

 no. Protophloem and earliest lignified xylem in transverse section of stem near 



apex. See lettering on fig. 107. 

 PLATE 14: 



in. Lower epidermis of leaf. X 210. 



112. Upper epidermis of leaf. X 210. 



113. Transverse section of leaf ; chloroplasts diagrammatic. X 210. 



114. Diagrammatic transverse section of rachis near summit; xylem shaded; ;//, 



parenchymatous region connecting with stomata; tr, trace of pinna. 



115. Inner surface of indusium, near margin. X 210. 



116. Cavity parenchyma (d) in transverse section of rachis. X 210. 



117. Ditto, in longitudinal section. X 210. 



118. Early stage of leaf-initial in transverse section of stem apex. 



119. Outer surface of indusium. X 210. 



120. Inner surface of indusium, near base, with stomata. X 210. 



121. Formation of leaf-initial in stem apex; later stage than fig. 118. Transverse 



section. 

 PLATE 15: 



122-127. Serial transverse sections of leaf-rudiment, showing transition from four- 

 sided to two-sided initial; 122 is through apex of rudiment, 127 through 

 its base. 



128, 129. Longitudinal sections of stem apex with leaf-rudiment, taken 0.025 mm. 

 apart; ;//, region of stem-initial; o, leaf-initial; , stem-initial. 



130. Longitudinal section of leaf-rudiment in radial longitudinal section of stem. 



X 360. 



131. Transverse section of two-sided leaf-initial, from a leaf with three pairs of 



pinnae. 



132-134. Serial sections (obliquely sagittal) through one end of leaf-initial, showing 

 segments and sections. From a leaf with four pairs of pinnae. 



135. Longitudinal section of leaf-initial; from a leaf with three pairs of pinnae. 



136. Longitudinal section of leaf-tip; no pinnae. 



137. Surface section of leaf-tip with marginal initials. 



PLATE 16: 



138. Longitudinal section of leaf with five pairs of pinnae, showing loss of initial. 



Segments i and 2 formed successively on same side of apical cell. 

 X 360. 



139. Sagittal section of leaf-rudiment with three pairs of pinnae, becoming circinate. 



Heavy lines bound segments. 



