188 Nebraska Agricultural Exp. Station, Research Bui. 6. 
Table 83. — Summary of stomatal and epidermal relationships with 
corn. 
Number of stomata per square inch of upper epidermis 49,665 
Number of stomata per square inch of lower epidermis 59,985 
Total number of stomata per square inch of leaf 109,650 
Average leaf-area per plant for 11 varieties (square inches) .... 949 
Total number of stomata per plant 104,057,850 
Average dimensions of stomatal aperture (microns) 25.6x3.5 
Average area of stomatal aperture (square microns) 89 
Area of average epidermis occupied by stomatal apertures 
(per cent) .76 
Area of leaf occupied by stomatal apertures in both epider- 
mises (per cent) 1.52 
(The stomatal aperture is practically closed at night and 
when the leaf is wilted.) 
Average thickness of leaf (microns) 200 
Average thickness of upper epidermis (microns) 35.2 
Average thickness of lower epidermis (microns) 26.0 
Relative thickness of upper epidermis to leaf (per cent) 17.6 
Relative thickness of lower epidermis to leaf (per cent) 13.2 
Relative thickness of total epidermis to leaf (per cent) 30.8 
Fig. 23. — Microphotograph of 0.83 square millimeter of corn-leaf epidermis. 
TISSUES CONCERNED IN THE TRANSPIRATION CURRENT OF 
CORN 1 . 
TECHNIQUE. 
The material for the histological work in this paper was 
secured from plants in active growing condition in the field. 
The material for leaf sections was cut from the leaf by means of 
1 References on the histology of the vegetative parts of the corn plant: 
Bessey (1889), Burtt-Davy (1914), Combs (1897), Harshberger (1897), Mont- 
gomery (1913), and Timiriazeff (1912). 
