Dec, 1922] 
RUTH EFFECT OF BORDEAUX MIXTURE 
547 
If whole leaves had been taken as units, and if an examination had been 
made at "Age C," it is possible that the photosynthetic activity of the 
sprayed leaves would have been found to be about the same as that of 
unsprayed leaves, because the chlorophyll content of the sprayed and 
unsprayed leaves was approximately equal. On the other hand, the effect 
of the Bordeaux mixture upon other conditions involved in photosynthesis 
might prove such an assumption to be groundless. In fact, it is more 
probable that photosynthesis was decreased; at any rate, in the experiment 
reported above on the effect of disbudding, a direct relation was shown 
between a high chlorophyll content of unit areas and a rapid increase in 
the area of the whole leaf, while the same positive relation between the 
chlorophyll content and the growth rate held at the various ages. More- 
over, the decreased respiration produced by Bordeaux mixture under 
conditions similar to those of this experiment (Ewert, 1905) might indicate 
a lowered photosynthetic activity, since a positive relation between photo- 
synthesis and respiration, except under extreme conditions, has been proven 
by Spoehr and I.ong (1919). Plester (1912) concludes that structure, 
which is evidently changed by Bordeaux mixture, is a factor in the rate of 
photosynthesis of varieties of the same species differing in their chlorophyll 
content, and Rose (1913, p. 105) arrives at the same conclusion as the result 
of his work on the photosynthetic rate manifested by leaves developed under 
different conditions of illumination. Another factor which might be 
affected is the activity of an enzym to which Willstatter and Stoll (191 5) 
attribute the high photosynthetic activity of very young, etiolated, and 
chlorotic leaves in which the photosynthetic rate is much above the rate 
indicated by their chlorophyll content. Certain investigators, including 
Frank and Kriiger (1894) Bain (1902), have found greater amounts of 
starch in the leaves of plants treated with relatively insoluble copper 
compounds, including Bordeaux mixture. These investigators have con- 
cluded that photosynthesis has been increased. Ewert (1905), however, 
finds that the yield is always lowered by Bordeaux mixture, whether it is 
measured in starch, in protein, or in dry weight. He finds that respiration 
is decreased and the rate of translocation of carbohydrates is lessened, the 
latter effect accounting for the apparent increase in assimilation observed 
by earlier investigators. He attributes the decreased growth which he 
obtained to a poisoning exerted on various activities of the plant, including 
diastatic activity. 
Aside from the harmful effect upon photosynthesis, which Bordeaux 
mixture may have in ways like those above suggested, it would seem that 
the increase in transpiration which it evidently brings about would be 
harmful to growth, unless the water content of the growing cells is main- 
tained, possibly by an increased activity in water absorption by the root. 
Environmental Conditions. The conditions for the growth of the plants 
used in this experiment were extremely favorable to rapid and normal 
