SECOND PART 



THE STRUCTURE AND LIFE OF PLANTS 



DIVISION I. 

 The Minute Structure and Vital Processes of Plants, 



I —THE SINGLE CELL 



1. The illustration of the vertical section of a leaf, as seen 

 under a microscope, shows that the leaf of a plant does not con- 

 sist of a homogeneous mass like iron or glass, but of several 



Fig. 181. — Transverse section of a leaf, to show its composition 



of cells. 



small ])arts, called Cells, wliich like the stones of a wall, consti- 

 tute the whole. Like the leaf, the other parts of a plant, viz., 

 root, stem, Hower, and fruit, are all composed of cells. 



