78 VEGETABLE PHYSIOLOGY 
sometimes free, and sometimes disposed in the form of an 
open network, are surrounded by delicate parenchymatous 
tissue, whose cells are in immediate contact with the woody 
Fic. 59.—Enpine or 4 Frpro-vascuLtar BUNDLE IN THE 
PAaRENCHYMA OF A LEAF. 
elements, as they are in the root (fig. 59). These delicate 
cells are also in contact with the special parenchyma of the 
leaf, which is in part very loosely arranged and provided 
with a great development of the intercellular space system 
Fig. 60.—TRANSVERSE SECTION OF THE BLADE oF A LEAF, SHOWING 
THE INTERCELLULAR SPACES OF THE INTERIOR. xX 100. 
(fig. 60), which we have seen to be characteristic of the whole 
of the tissue of the plant. The cells abutting on the bundles 
are filled, like the root-hairs and the cells of the cortex, 
with a watery sap which contains substances exerting a 
relatively high osmotic pressure. The woody elements 
