Feb. 28,1916 
Relation of Stomatal Movement to Infection 
1031 
was carried on in August, 1913, near Rocky Ford, Colo., and the read¬ 
ings of the two types of leaves from the same plant were made near 
together so that all time factors might, so far aS possible, be eliminated. 
The results show that on the average the number of stomata is less and 
their pore length is greater (Table X) on the infected leaves than on the 
uninfected, showing the greater maturity of the former. Some varia¬ 
tions in these numbers occur, but it is to be noted that the four infected 
leaves vrith the greatest number of spots present have, on the average, 
fewer stomata per square millimeter of leaf surface and a greater stomatal 
pore length than the four infected leaves with the least number of spots. 
Table X.— Comparative average maturity of Cercospora beticola infected (young mature) 
and uninfected leaves {heart) of the sugar-beet plant as shown by the number and pore 
length of the stomata. Readings 1 taken on August 5 to jj, IQIJ, at Rocky Ford, Colo . 
INFECTED YOUNG MATURE LEAVES 2 
Leaf No. 
Size of leaf. 
Length. 
Width. 
Average number of 
stomata. 
Upper leaf 
surface. 
Lower leaf 
surface. 
Average stomatal pore 
lengths. 
Upper leaf 
surface. 
Lower leaf 
surface. 
Number 
of leaf- 
spots 
per leaf. 
1 
2 
3 
4 
5 
6 
7 ' 
8 , 
9 
io, 
ii , 
Cm. 
i7-5 
i 7 
9-5 
14-5 
10 
i 5 
ii* 5 
i 5 
io- 5 
13*5 
Cm. 
12.5 
12-5 
9 
10 
7*5 
9 
io *5 
12 
12.5 
8.5 
9-5 
98. 4 (3] 
68.06I 
95-1 
102. 5 
106. 6 
no. 7 
77*9 
114. 8 
118. 9 
114. 8 
133-9 
123 
106. 6 
hi. 5 
127.9 
155-8 
139-4 
123 
137-3 
164 
172. 2 
183.1 
19 
19 
19 
19 
19 
19 
IK. 2 (6, 
17. 1 (6 
15- 5 (5 
19 ( 4 
IS - 2 (4) 
Average. 
13 - 1 
10.3 
103.8 
140.3 
17.8 
17.8 
24 
21 
21 
14 
9 
5 
5 
3 
3 
1 
1 
UNINFECTED HEART LEAVES 2 
1 . 
2 . 
3 . 
4 . 
5- .. 
6 . 
7 . 
8 . 
9. 
10 . 
11 . 
Average 
14-5 
14 
8-5 
12.5 
13 
10.5 
13 
9 
13 
9 
12. s 
11. 8 
9-5 
9-5 
8 
8 
8 
7 
9- 5 
9-5 
10 
6- 5 
9-5 
8.6 
145-9 
164 
172. 2 
147.6 
166. 4 
184.5 
174.6 
205 
184.4 
22K 
24I.9 
196. 8 
i 87*5 
19 
15-9 
17. 1 
13 -1 
13.6 
15-2 
11.4 
13-9(5 
13-3 (8 
13-3 
12. 1 
14.4 
i7-4(3 
15-2 (5 
iS-2 (5 
15-2 
15.2 
17.1 
13-3 
II. 4 
13- 3 
15-2 
14- 4 (.5, 
14. 8 
1 The number of readings made per leaf is given in parentheses following each average. 
2 Infected leaf 1 was on the same plant as uninfected leaf t, infected leaf 2 was on the same plant as un¬ 
infected leaf 2, and so on through the series. The leaves of each pair were read at the same time. 
