Apr. is. 19*1 
Bacterial Spot of Tomato 
147 
Table V— Relative susceptibility of upper and lower epidermis 
Plant. 
Inoculation. 
Total 
number 
of leaf¬ 
lets. 
Leaf! 
Total 
num¬ 
ber. 
ets show 
Per¬ 
cent¬ 
age. 
ing infec 
More t 
lcsit 
Num¬ 
ber. 
lion. 
tian 10 
ms. 
Per¬ 
cent¬ 
age. 
A 41 
Lower epidermis . 
32 
18 
56 
IO 
3 1 
A 42 
Upper epidermis. 
36 
IO 
28 
I 
3 
B 44 
Lower epidermis. 
43 
30 
69 
22 
51 
B45 
Upper epidermis. 
40 
23 
57 
IO 
25 
C 44 
Lower epidermis. 
32 
7 
22 
5 
16 
c 45 
Upper epidermis. 
33 
1 
3 
0 
0 
D 44 
Lower epidermis. 
39 
29 
74 
27 
69 
E 45 
Upper epidermis. 
40 
6 
15 
1 
2 
E 41 
Lower epidermis . 
37 
18 
49 
14 
37 
E 42 
Upper epidermis . 
27 
6 
22 
6 
22 
Aver- 
fLower epidermis . 
54 
41 
\Upp p r epidermis . 
25 
IO 
Thus, it is seen that the average percentage of infected leaflets on 
plants atomized from below is 54 as compared with 25 on plants atomized 
from above, and that the difference is still more striking when the per¬ 
centages of heavily infected leaves are compared, in which case the 
figures are 41 and 10, respectively. 
This decidedly higher incidence of infection through the lower epider¬ 
mis suggested some connection with the distribution of stomata. To 
throw further light on this point, portions of the epidermis from the 
upper and lower surfaces of several leaves were removed and mounted so 
that stomatal counts could be made under the microscope. The results 
are presented in Table VI. 
Table VI .—Number of stomata per square millimeter of epidermis 
Source of epidermis. 
Upper epi¬ 
dermis. 
Lower epi¬ 
dermis. 
Young plant, young leaf.. 
50 
K 
117 
98 
131 
246 
306 
93 
61 
Young plant, old leaf. 
Do. 
J 
O 
Old plant, young leaf. 
7 
Do. 
O 
II 
Cotyledon... 
41 
83 
Do.... 
