190 Nebraska Agricultural Exp. Station, Research Bui. 6. 
a small corn stem showing the scattered arrangement of the 
vascular strands. The cut ends of the vascular tubes may be 
seen in this figure. Water rises thru the vascular tubes of the 
stem and passes into the leaves thru the vascular bundles shown 
in Figure 4. Figure 4 is a cross section of part of a corn leaf. 
Here may be seen the two epidermal layers which are nearly 
impervious and serve to practically prevent water loss except 
that which passes thru the stomata, a number of which may be 
seen in section on both sides of the leaf. Figure 5 represents 1.3 
square millimeters of lower epidermis. This shows the definite 
arrangement of the stomata in rows as well as the stomatal 
apertures thru which the internal water is evaporated into the 
air. 
Plate II shows various studies of the epidermis, both upper 
and lower surfaces. With the exception of Figure 8 which is 
diagrammatic, all figures were made with the camera lucida. 
Figure 1 is a cross section of the upper epidermis, showing the 
relative size of normal upper epidermal cells and the relative 
thickness of the walls. Figure 2 is a longitudinal section showing 
the same features. Figure 3 and 4 are cross sections of the upper 
epidermis showing groups of enlarged cells to which has been 
attributed the seat of leaf curling in time of water scarcity. 
Figure 5 is a longitudinal section of these enlarged cells. Figure 
6 is a cross section of the lower epidermis, showing normal cells. 
Figure 7 is a longitudinal view of the cells of the lower epidermis. 
Figure 8 is a surface view of the lower epidermis. This figure 
shows diagrammatically the arrangement of the epidermal 
cells and stomata in rows extending lengthwise of the leaf. The 
prominent nuclei in the cells of the epidermis as well as the 
subsidiary cells of the stomata, are evident. Figure 9 shows 
more in detail the relation of a single stoma and the surrounding 
epidermal cells. The incurving of the walls of the epidermal 
cells to meet the walls of the subsidiary cells is quite characteristic. 
Figure 10 is a single stoma as seen under an oil immersion lens. 
The prominent nuclei of the subsidiary cells as well as the chloro- 
plasts located in the ends of the guard cells are features to be 
noticed. The number of plastids varies in different stomata. 
The aperture between the guard cells is the stoma proper, altho 
the whole structure is often referred to as the stoma. Figure 11 
is a cross section of a stoma of the same magnification as Figure 
10. This section is taken somewhere in the region of the two 
nuclei of the subsidiary cells. Figure 12 is a leaf hair, which is 
a single modified epidermal cell. 
Plate III shows various studies of sections of the leaf. Figure 
1 is a longitudinal section of a leaf in the region midway between 
