PRATT: CYCLOLOMA ATRIPLICIFOLIUM. 119 



PLATE XV. 



Fig. 73. Portion of cross section of the leaf, showing structure between 

 the bases of two lobes on one side of the leaf. Corresponding parts lettered 

 as in fig. 72: q', oil globule; r', glucoside globule; s', mass of calcium oxalate 

 crystals in a cell of the water-storage tissue; /", stoma. X 330. 



Fig. 74. Surface view of cells of the upper epidermis, showing type and 

 frequency of stomata. X 225. 



Fig. 75. Surface view of cells of lower epidermis, showing type and fre- 

 quency of stomata. X 225. 



Fig. 76. Surface \-iew of the lengthened cells of the upper epidermis 

 over the main rib, showing type and frequency of stomata. X 225. 



Fig. 77. Clothing hairs of the epidermis of a very young leaf: a, basal 

 cell; k', cuticle, q', oil globule; u', terminal portion; a", basal portion of one 

 or more short cells above the basal cell. X 330. 



Fig. 78. Glandular hairs of the epidermis of a very young leaf: a, basal 

 cell; k', cuticle; V, dense cell, contents in the terminal spherical cell; u', ter- 

 minal portion; a", basal portion; c", small oil globule; d", large oil globule. 

 X 330. 



PLATE XVL 



Fig. 79. Portion of a tangential section of a leaf bleached in 5 per cent 

 potassium hydroxide: d, water-storage tissue; e, spiral tracheal tube of the 

 vascular elements; n'", border parenchyma cells ha\'ing end walls pitted. 

 X330. 



Fig. 80. Surface \iew of a bleached leaf, embracing the epidermal, the 

 palisade and the vascular bundle systems. X 330. 



Fig. 81. Portion of a tangential section of the leaf, showing cells of the 

 epidermis, a, and mesophyll parenchyma, «'", under the water-storage tissue: 

 k', cuticle; p', intercellular space. X 330. 



Fig. 82. Portion of a cross section of the leaf to show collenchyma in 

 the tip of a lobe of the leaf: a, epidermis; h, collenchyma; k', cuticle; n'", 

 mesophyll parenchyma. X 80. 



PLATE XVIL 



Fig. 83. Bleached leaf, showing venation: d, water-storage tissue be- 

 tween the three largest veins. X 17.5. 



Fig. 84. Blind ending of the venation in the midst of the mesophyll, 

 showing spiral, p", annular, q", and reticulate, r", tracheids. X 330. 



Fig. 85. Groups of spiral, p", annular, q", and reticulate, r", tracheids, 

 which extend out close to the expidermis and serve as the ultimate endings 

 of the venation at the edge of the leaf. X 330. 



Fig. 86. Portion of a tangential section of the leaf to show pits in end 

 walls of border parenchyma cells, o'", are not conspicuous in unbleached 

 sections: j, vascular elements. X 330. 



Figs. 87-89. A series of cross sections of the petiole of the leaf proceeding 

 upward: a, epidermis; h, collenchyma; e, photosynthetic tissue; d, water- 

 storage tissue; e, border parenchyma: p", q", r", s", and t", five vascular 

 bundles of the petiole. 



