17 2 Bulletin Jard. Bot. Buitenzorg, Série III, Vol. V. Livr. 2. 



Fig. 109. Another view of tfie above haustorium with the constriction showing. 

 The parallel ridges of the haustorium are also seen. X 2'/2. 



Fig. 110. Cross section of the haustorium. Dotted area is the spongey tissue, the 

 peripheral zone of several cells in thickness, the active digestive and 

 absorptive zone. X 2V2- 



Fig. 111. Haustorium with the neck-piece showing ttie flattened upper por- 

 tion. X 2'/.. 



Plate Xiil. 



Fig. 112. Section of growing haustorium taken from a stage shown in (Fig. 128 

 Plate XVI) shows the three outermost layers in an active state of division. 

 The outermost cells are devoid of starch grains; the cytoplasm is denser 

 with many large and small vacuoles. The middle iayer with many small 

 starch grains has a decidedly lighter staining cytoplasm. In the Ihird laver 

 the long axis of the cells is in a vertical plane. The starcli grains are 

 strikingly larger. Fixed in Juel's Solution and stained with Heidenheins 

 haematoxylen. Zeiss Oc, no. 4 X Obj. N. A. 1.3, Abbe Caméra lucida. 



Plate XIV. 



Fig. 113. Sector of a cross section of a root the next stage in the formation of the 

 air chambers shown in Figure 54, Plate VII. They originate always radially 

 but apparently with no definite regularity. X '60. 



Fig. 114. Sector of a cross section of a root showing fully formed air chambers 

 with lamellae ranging from 1 to 6 cells in thickness. Torn cells line the 

 air chambers. X 160. 



Fig. 115. Sector of a cross section of an adventitious root. The air chambers are 

 smaller, more compressed. Hypoderniis is strongly developed and the bast 

 cells occupy most of the région previously composed of thin celled 

 parenchyma. The cells of the endodermis are greatiy thickened liowever 

 the circle of endoderm is not continuons, the breaks made iipof thin walled 

 cells allow for ready communication between the central cylinder and cortex, 

 Stone cells are strongly developed in a zone outside of the endodermis. 

 The large oval cells in the cortex near the hypoderniis are the raphide 

 cells. X iGO. 



Plate XV. 



Fig. 116. Part of cross section of a root showing large epidermal cells, beginning 



of hypoderniis, parenchyma, a single raphide cell in the centerof the section 



and bast cells. X 600. 

 Fig. 117. Epidermal cells in longitudinal section. X 600. 

 Fig. 118. Group of bast cells. X 600. 

 Fig. 119. Longitudinal eut tlirough a young plant cutting through several roots 



showing the présence of lacunae. X 2. 

 Fig. 120. Longitudinal eut through somewhat older plant showing the relation of the 



vascular System to the roots (the bundles run to Ihe base where the roots 



émerge). X 2. 

 Figure 121 to 126. Showing adventitious roots in varions espects. In Figure 124 the 



émergence from the branch to the right is a pneumaihode. X '• 



