184 Nebraska Agricultural Exp. Station, Research Bui. 6. 
CORRELATIVE RESPONSE OF LEAF STRUCTURE AND TRAN- 
SPIRATION, AS RELATED TO VARIETY, ACCLIMATIZATION, 
AND SOIL CONDITIONS. 
Careful measurements of leaf thickness and the relative num- 
ber of stomata per unit leaf -area were made with the corn and 
sorghum varieties grown in the 1914 variety and acclimatization 
test. The relative number of stomata was also determined for 
the corn plants grown in the different degrees of soil moisture 
and of soil fertility in 1914. 
For these histological studies two leaf sections were taken 
by means of a Ganong leaf punch from each of three leaves of 
every plant. The leaves selected were the ear leaf and the leaf 
on either side. It was considered that these three central leaves 
would be fairly representative for the entire plant. The sections 
were taken in the widest portion of the leaf midway between 
the midrib and the margin. Since there were four duplicate 
potometers, 24 leaf samples were obtained for each variety or 
treatment. To determine the relative number of stomata, the 
number in 120 separate fields under the microscope was counted 
for each variety or treatment. To determine the epidermis and 
leaf thickness, 30 to 60 measurements were made for each. For 
stomata counts, the epidermis was stripped from the leaf. The 
thicknesses were measured from stained microtome sections of 
material imbedded in paraffin. The technique is explained in 
detail on pages 188 and 189. 
By reference to Table 80 it will be seen that considerable 
variation existed between the different varieties in regard to 
the thickness of the leaf and of the epidermis and also in the 
number of stomata per unit leaf -area. There was, however, no 
apparent striking or consistent correlation between these histo- 
logical coefficients and the transpiration rate per unit dry matter 
or per unit leaf-area of the different varieties. It is also evident 
from Tables 81 and 82 that there was no very striking response 
in the relative number of stomata to variation in either soil 
moisture or soil fertility. The reader is referred to the tables 
which follow for a summary of these relationships. 
Some very interesting histological generalizations concern- 
ing corn may be drawn from the 11 varieties grown in the potom- 
eters in 1914. These are tabulated in Table 83. 
