546 
AMERICAN JOURNAL OF BOTANY 
[Vol. 9, 
phyll content of the average sprayed and of the average unsprayed leaf was 
practically the same, averaging 2.02 milligrams to the sprayed leaf and 
2.07 milligrams to the leaf which had not been sprayed. Averages for the 
six flats are presented in table 5. 
Table 5. Average Chlorophyll Content {in Milligrams) of the Primary Leaves of Sprayed 
and Unsprayed Plants 
Flat 
I 
2 
3 
4 
5 
6 
Average 
Sprayed 
2.12 
2.05 
2.18 
1.88 
2.08 
1.80 
2.02 
Unsprayed 
2.1 1 
2.50 
1.99 
1.83 
1.94 
2.05 
2.07 
This was not due to an increase in the weight of the sprayed leaf per 
unit area, as table 6 shows. 
Table 6. Weight of Sprayed and Unsprayed Leaves {in Grams) per Square Centimeter 
Flat 
I 
2 
3 
4 
5 
6 
Average 
Sprayed 
,0204 
.0187 
.0187 
.0164 
.0185 
.0189 
.0186 
Unsprayed 
.0189 
.0204 
.0195 
.0157 
.0189 
.0193 
.0189 
The primordial leaves of the sprayed plants in all the flats contained 
the greater amount of chlorophyll per gram of fresh leaf. The data are 
presented in table 7. 
Table 7. Chlorophyll Content {in Milligrams) per Gram, Fresh Weight 
Flat 
I 
3 
4 
5 
6 
Average 
Sprayed 
2.14 
2.00 
2.04 
2.30 
1.82 
2.00 
2.05 
Unsprayed 
1-75 
1.97 
1.96 
2.17 
1.61 
1.86 
1.89 
Discussion 
Probable Relations between Photosynthesis and the Increased Chlorophyll 
Content. It has been shown that the chlorophyll content of unit areas and 
of unit fresh weights has been increased by spraying rapidly growing leaves 
with Bordeaux mixture. This increase is accompanied by a smaller leaf 
area. No experiments were carried out to determine the effect upon 
photosynthesis; this is one of a series of topics outlined for further experi- 
ment. Amos (1907), experimenting with leaves of the hop, grape, and 
Jerusalem artichoke, found that Bordeaux mixture temporarily checked 
photosynthesis After the effect of the temporary check had disappeared, 
photosynthesis became normal but did not exceed that of unsprayed leaves. 
No effect of the spray on the color of the leaves was reported, which prevents 
the direct application of his conclusions to this experiment. 
