Feb. 28,1916 
Relation of Stomatal Movement to Infection 
1023 
Table VII .—Effect of varied temperature and relative humidity on stomal pore open¬ 
ing on sugar-beet leaves at Rocky Ford, Colo., in 1913—Continued 
Date and time of 
reading. 
Tem¬ 
pera¬ 
ture. 
In humidity box. 
Rela¬ 
tive 
hu¬ 
midity. 
Average stomatal 
pore widths. 
Upper 
leaf 
surface. 
Lower 
leaf 
surface. 
Tem¬ 
pera¬ 
ture. 
In greenhouse. 
Rela¬ 
tive 
hu¬ 
midity. 
Average stomatal 
pore widths. 
Upper 
leaf 
surface. 
Lower 
leaf 
surface. 
May 20:® 
5.00 a.m 
6.00 a.m 
7.00 a. m 
8.00 a. m 
8.30 a.m 
9.00 a. m 
9.30 a. m. 
10.30 a. m. 
11.00 a. m. 
11.45 a. m. 
1.30 p.m. 
2.15 p.m, 
2.4s p.m. 
* 3.30 p.m. 
4.00 p.m. 
June 3: 
7*45 a.m. 
9.00 a.m. 
9.30 a.m. 
10.00 a. m. 
10.15 a. m. 
10.30 a. m. 
11.45 a.m. 
12.15 a.m. 
1.30 p. m. 
2.00 p.m. 
2 30 p.m. 
3.00 p.m. 
3.30 p.m. 
F. 
Per ct. 
50 
95 
0.3 1 
(6) 
O. 4 1 
ft 
51 
95 
•7 < 
8) 
1.8 i 
9) 
53 
94 
•3 < 
1.6 < 
In 
56 
85 
3. 24 1 
> 7 ) 
5 < 
6) 
63 
76 
2.16 \ 
6) 
2.8 < 
6) 
64 
75 
. 5-7 < 
6) 
7.2 1 
5 ) 
64 
75 
6.1 1 
7.2 < 
>9) 
65 
66 
5-7 < 
6) 
5-7 < 
> 4 ) 
68 
65 
7.2 1 
J6) 
7.2 < 
:6) 
7 i 
66 
7.2 1 
> 4 < 
7-2 < 
I 4 < 
75 
57 
9 < 
> 4 } 
11 < 
5 < 
75 
58 
7.2 1 
J6) 
7-5 < 
.5) 
73 
57 
7.2 i 
> 5 ) 
7.2 < 
> 4 ' 
74 
53 
5-7 < 
> 5 ) 
3-2 < 
. 5 ) 
75 
53 
6.8 1 
. 5 ) 
6.1 < 
:a) 
67 
100 
3-6 ( 
4-3 ( 
I 4 ) 
70 
100 
6.3 < 
> 4 < 
7 * 38 ( 
>4 ) 
72 
100 
7-5 < 
> 4 .) 
7.2 ( 
,4) 
74 
100 
7-5 < 
> 4 < 
7*4 < 
. 4 ) 
80 
100 
7.2 ( 
> 4 ) 
7-3 ( 
Is) 
82 
100 
6.4 < 
.4) 
5-8 ( 
A 
93 
100 
9-3 < 
> 4 < 
9-3 < 
>3) 
94 
97 
7-8 ( 
> 4 > 
8.5 < 
.4) 
96 
93 
7.02 ( 
.6) 
7-5 < 
Is) 
94 
95 
9-4 < 
9-4 < 
[ 6 ) 
85 
95 
7-8 < 
>5) 
7.8 ( 
a ) 
89 
100 
5-4 < 
.6) 
6.4 ( 
;6) 
75 
IOO 
5*4 < 
.6) 
4-3 < 
.5) 
F. 
Per ct. 
5 i -5 
93 
52 
91 
54 
83 
61 
65 
63 
64 
65 
59 
65 
59 
67 
53 
68 
57 
72 
53 
74 
45 
74 
42 
71 
42 
7 i 
42 
74 
40 
69 
69 
67 
64 
69 
7 i 
75 
68 
73 
75 
73 
67 
79 
62 
82 
63 
80 
56 
80 
58.5 
75 
57 
75 
57 
75 
57 
o 
o. 25 
.14 
2.8 
2.1 
3-9 
4.6 
5 
1. 8 
2.1 
1. 08 
3-2 
3 - 6 
i-5 
2.1 
1.8 
2 . 5 
2.8 
4.4 
6.1 
7. 2 
4 - 5 
9.4 
3-8 
1. 6 
5 - 8 
o 
o 
0.3 (9) 
.2 (10) 
. 28 (10) 
1.4 (8) 
2. 1 (7) 
4-3 (6) 
3-8 (6) 
7-5 ( 7 ) 
*•4 ( 7 ) 
0 W 
1.08 ( 6 ) 
1.6 (6) 
4.06 ( 6 ) 
o (5) 
o (s) 
1. 08 (4) 
* 14 i S l 
o (5) 
2-5 ( 5 ) 
6.1 W 
6-8 (5) 
t 1 > 5 < 
8.1 (3) 
2-7 \ 9 > 
2.3 (12) 
o (8) 
0 (s) 
o (6) 
a Intermittent clouds and sunshine up to 11.4s a. m., then bright sunshine until 2.25 p. m.; cloudy to 
3.30 p. m., and then sunshine for the rest of the day. 
Usually the temperature in the humidity box was practically the same 
as that outside in the greenhouse at the same time. Although no definite 
study has been made to determine the temperature most favorable to 
stomatal movement, it is to be noted that good stomatal opening occurred 
between 8 a. m. and 5 p. m., and during that time the temperature 
increased, on the average, from about 65° to 85° F. and decreased to 
8o° F. Only on June 3 was the temperature in the humidity box much 
higher than that outside in the greenhouse, and it appears that neither 
of these temperatures (96° in the humidity box and 8o° in the green¬ 
house at 1.30 p. m.) produced a change in the degree of stomatal opening. 
On the other hand, the humidity in the two places was quite different, 
being always higher inside than outside of the humidity box. To this 
difference in humidity the marked variation in the pore opening of the 
stomata has been attributed. For example, on May 16 the humidity 
ranged about 30 units higher inside than outside of the box (fig. 2), 
and the stomata were well open in the former place and closed practically 
throughout the day in the latter. On the upper leaf surface in the 
greenhouse only slight opening occurred at 9 a. m. and this disappeared 
