LIST OF ILLUSTRATIONS AND EXPLANATION OF PLATES. 53 
PLATE 12, continued: 
93-90. Diagrams of successive cross-sections of petiolar bundle giving off a leaf- 
shoot bundle. Conventional signs as in figs. 83-87; 7, leaf-shoot. 
97. Diagrammatic cross-section of leaf-shoot, nearits origin. Conventional signs as 
in figs. 88-92; 2 indicates part drawn in fig. 63. 
98. Isolated tracheids of fork of stem. 
99. Diagram a fork of stem, longitudinal section. Conventional signs as in figs. 
3-87. 
100. sii ale eae (loseeecuen of node; stem to right. Conventional signs as in 
gs. 83-87. 
1o1, Diagrammatic transverse section of base of petiole. Conventional signs as in 
figs. 88-93; @, region of stomata. 
102. Diagram of junction of root and stem, longitudinal section. Cortex and 
medulla section-lined. 
PLATE 13: 
103. dae with four segments, in transverse section, with leaf-rudiment, d, at 
eft. XX 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; @, intercalary growth of hair; z, origin of hair. 
Composite. X 21o. 
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. 210. 
109. Oblique transverse section of stem-initial, with leaf-rudiment (4) in fourth 
segment. X 360. 
110. Protophloem and earliest lignified xylem in transverse section of stem near 
apex. See lettering on fig. 107. ; 
PLATE 14: 
111. Lower epidermis of leaf. x 210. 
112. Upper epidermis of leaf. xX 210. 
113. Transverse section of leaf; chloroplasts diagrammatic. 210. 
114. Diagrammatic transverse section of rachis near summit; xylem shaded; wz, 
parenchymatous region connecting with stomata; ¢7, trace of pinna. 
115. Inner surface of indusium, near margin. X 210. 
116. Cavity parenchyma (@) in transverse section of rachis. X 210. 
117. Ditto, in longitudinal section. % 210. 
118. Early stage of leaf-initial in transverse section of stem apex. 
11g. 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; #z, region of stem-initial; 0, leaf-initial; 6, 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 
pinne. 
132-134. Serial sections (obliquely sagittal) through one end of leaf-initial, showing 
segments and sections. From a leaf with four pairs of pinne. 
135. Longitudinal section of !eaf-initial; from a leaf with three pairs of pinne. 
136. Longitudinal section of leaf-tip; no pinne. 
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 1 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, 
