116 Nebraska Agricultural Exp. Station, Research Bui. 6. 
The data indicate that a transpiring leaf is uniformly cooler 
than a dead one, amounting (under the high air temperatures of 
1913) to a difference of 8.5° F. in the sun at 2 p. m. when tran- 
spiration is maximum, and 4.2 degrees in the shade at the same 
time. Averaging the sun and shade temperature for the day we 
find that the average daily temperature of the green leaf is 2.2° F. 
below the air temperature, while the dry leaf is 1.6° F. higher 
than the air. A probable reduction of 4° F. in the temperature 
of the leaf due largely to the transpiration is sufficient to exert 
a marked protection against water loss. The degree of leaf- 
temperature reduction would doubtless vary with climatic con- 
ditions. 
We cannot conclude that it is one of the purposes of transpira- 
Table 42. — Summary of plant temperature records in the cornfield. 
1912. All temperatures were taken in the shade. {Average 
for week, August 25 to August 31.) 
Time of day 
Degrees temperature in shade 
Leaf 
Stalk 
Leaf sheath 
Ear 
Air 
(1) 
7:30 a. m 
2:00 p. m 
5:30 p. m 
Degrees F. 
(2) 
76.3 
90.7 
84.2 
Degrees F. 
(3) 
73.7 
87.4 
83.0 
Degrees F. 
(4) 
73.9 
86.0 
81.0 
Degrees F. 
(5) 
72.8 
87.8 
85.2 
Degrees F. 
(6) 
75.6 
93.3 
87.6 
Average 
83.7 
81.4 
80.3 
81.9 
85.5 
Table 43. — Summary showing the temperature of different parts 
of the growing corn plant. (Average for 7 days — August U 
to 9, 1913.) 
Time of 
day 
Degrees temperature in shade 
Leaf 
Stalk 
Leaf sheath 
Ear 
Air 
CD 
7:30 a. m . . 
2:00 p. m. . 
5:30 p. m. . 
Degrees F. 
(2) 
76.6 
93.1 
92.0 
Degrees F. 
(3) 
74.8 
90.6 
91.5 
Degrees F. 
(4) 
74.8 
90.6 
91.6 
Degrees F. 
(5) 
74.8 
92.3 
90.8 
Degrees F. 
(6) 
76.3 
95.8 
95.1 
Average. . . 
87.2 
85.6 
85.7 
86.0 
89.1 
