120 THE UNIVERSITY SCIENCE BULLETIN. 



Fig. 87. Cross section from the base of the petiole. X 48. 



Fig. 88. Cross section midway between the base and the tip of the 

 petiole. X 48. 



Fig. 89. Cross section from the tip of the petiole, showing vascular- 

 bundle strands, o" and u", which are branches of p" and t", respectively. X48. 



Fig. 90. Portion of a cross section midway between the base and the tip 

 of the petiole, showing two vascular bundles, j: d, water-storage tissue; 

 e, border parenchyma; d'", sieve tube having thick walls. X 330. 



PLATE XVIII. 



Figs. 91 to 94, inclusive. A series of cross sections of the stem in region 

 IV, from below the petiole attachment to a little above. The anomalous 

 tissue is colored black. 



Fig. 91. Section of the stem just below the petiole aUachment, showing 

 the five leaf-trace bundles, p", q", r", s" and t", about to enter the petiole. 

 Corresponding parts lettered as in fig. 2. X 48. 



Fig. 92. p", q", r", s" and t" are in the leaf-trace gap, and are entering 

 the petiole. X 48. 



Fig. 93. p", q", r", s" and /" have left the leaf-trace gap, p'". X 48. 



Fig. 94. p'", leaf-trace gap partially closed. X 48. 



PLATE XIX. 



Fig. 95. Leaf-trace gap closed in a section of the stem just above the 

 petiole attachment. X 48. 



Fig. 96. General drawing of a leaf, bleached in 5 per cent potassium 

 hydroxide, to show the abundance of calcium oxalate crystals occurring in 

 the border parenchyma of the veins, and the water-storage tissue. The 

 areas colored black represent the location of the masses of crystals. 



