RELATION OF TRANSPIRATION TO STOMATA 
497 
maximum of 235 mg. in Impatiens per hour, average of day and night 
transpiration for the average of ten jars for about 40 days. 
The third column of Table II shows the total amount of water 
lost in grams by all the jars of each species used in series I. Column 
four shows the total, upper and lower, leaf surface in square centi- 
meters for each species used in series I. Column five shows the 
average amount of water transpired for each square decimeter of 
leaf surface per hour for each species. Table III records the same 
data for the second series (Series II). 
A comparison of the results of the two tables (Tables (II and III 
shows that the average amount of water transpired by each species 
as determined in the two series of plants varies but slightly. The 
largest difference is found in Pelargonium zonale and this is well 
accounted for by the fact that I accidentally used a different variety 
of Pelargonium for the second series. The results of Helianthus 
annuus may have been modified by an early attack of Erysiphe cichora- 
cearum, which prevented me from continuing the cultures for a longer 
period than five days in the second series. The first eleven days of 
weighings which were obtained from the first series were taken before 
there was any evidence of Erysiphe and, I think, represent normal 
transpiration. 
Table IV 
Showing the Minimum, Mean, Average, and Maximum Number of Stomata in One 
Square Millimeter Leaf Surface 
Name of Species 
Lower S 
urface 
Upper Surface 
Min. 
Mean 
Av. 
Max. 
Min. 
Mean 
Av. 
Max. 
Phaseolus vulgaris 
131 
269 
250 
327 
28 
40 
40 
50 
Ricinus cummunis 
79 
121 
172 
35 
68 
52 
76 
91 
103 
lOI 
no 
51 
61 
60 
83 
Primula sinensis 
49 
87 
84 
112 
0 
32 
52 
52 
72 
9 
18 
19 
24 
Pelargonium zonale 2 
190 
210 
215 
232 
4 
9 
8 
II 
Impatiens sultani 
105 
140 
143 
180 
12 
37 
29 
70 
Triticum sativum 
12 
21 
21 
27 
35 
46 
46 
55 
Helianthus annuus 
125 
170 
172 
198 
27 
70 
71 
90 
Table IV shows the number of stomata per square millimeter leaf 
surface for each of the several species. It will be noticed that all 
but one species, Triticum sativum, have fewer stomata on the upper 
surface than on the lower surface. I found that the number of 
stomata varied considerably in different parts of the same leaf. On 
