Feb. as, 1916 Relation of Stomatal Movement to Infection 1013 
ings were made of the stomatal numbers and pore lengths, together 
with the leaf size. These readings were taken during the same period 
and under comparable environmental conditions and the results are 
given in Tables I, II, and III, each leaf having been given the same 
number in all the tables. 
STOMATAL NUMBERS 
It is shown in the general averages of Table I that the number of 
stomata per square millimeter of heart-leaf surface (289.8, upper surface; 
353.5, lower surface) is more than 2 * l / 2 times that on mature leaves (100.7, 
upper; 130.6, lower), as would be expected. There are in turn more on 
the mature than on the old leaves (80.1 and 105), while cotyledons have 
the fewest of all (54.7 and 73.2). The plants studied were grown in the 
field at Madison, Wis., under favorable conditions, and at the time the 
readings were made they appeared normal in every way. The older 
plants were about 7 weeks old, and those from which the cotyledons 
were studied were 3 weeks old. The cotyledons were green and turgid, 
comparing in maturity and activity probably with those leaves termed 
“mature.” It may also be noted in the averages that more stomata 
were present on the lower surface of the leaves than on the upper and 
that the ratio between the two remained uniform. 
Table I .—Average number of stomata on the upper and the lower leaf surfaces of hearty 
mature , and old leaves and cotyledons of the sugar beet. Readings 1 taken at Madison, 
Wis., on July 6,1914. The number of readings made per leaf is given in parentheses 
following each average 
Leaf No. 
Heart leaves. 
Upper. Lower, 
Mature leaves. 
Upper. Lower 
Old leaves. 
Upper. Lower. 
Cotyledons. 
Upper. • Lower 
3 - 
4 - 
5 - 
6 . 
7 - 
8. 
9 - 
10. 
11. 
12. 
13 - 
14. 
i 5 * 
16. 
i 7 - 
j 9 . 
20. 
21. 
240.7 
293.8 
275-5 
298.8 
353‘5 
298.8 
3 i 5-4 
307-1 
3 2 o -3 
253-9 
3 ' 2 ) 
4 ) 
3 ) 
3 ) 
ii 
1) 
2 
92.9 
94.6 
94.6 
104.5 
124-5 
92.9 
104.5 
104.5 
99.6 
i° 9-5 
104.5 
1 4 1.1 
124-5 
126.1 
132.8 
129.4 
99.6 
126.1 
1 4 1.1 
1 2 1.1 
137-7 
154-3 
53 -i 1 
I 4 ) 
78.0 
(4) 
59-7 < 
6 ) 
102.9 
( 4 ) 
7!-3 < 
3 
86.3 
Is) 
74-7 ( 
2) 
99.6 
( 3 ) 
94.6 i 
4) 
116.2 
(3 
83.0 l 
2) 
104.5 
( 3 ) 
89.6 ( 
4 ) 
104.5 
( 3 ) 
92.9 < 
3 
126.1 
( 3 ) 
99.6 ( 
3 ) 
132.8 
( 3 ) 
83.0 ( 
;i) 
99.6 
(1) 
303-7 (3) 
398.4 (1) 
249.0 (1) 
323-7 (2) 
102.9 
99.6 
99.6 
913 
91-3 
127.8 (4) 
116.2 (1) 
149.4 h) 
132.8 (2) 
69.7 
66.4 
53 -i 
59-7 
76-3 
66.4 
74-7 
33-2 
49.8 
49.8 
38.1 
49.8 
58.1 
49.8 
54-7 (3) 
92-9 ( 5 ) 
78.0 (4) 
59-7 (3) 
257-3 (2) 
34°-3 (2) 
66.4 ( 3 ) 
41-5 
33-2 (2) 
49.8 (1) 
83-0 (1) 
49.8 (2 
66.4 (i 
Average 
289.8 
353-5 
100.7 
130.6 
80.1 
105.0 
54-7 
73-2 
1 These leaves were used for the readings given in Tables II, III, and V, and each leaf has the same number 
in all the tables. 
1 Numbers in italics indicate the maximum and minimum variation. 
