[Vor. 1 
10 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
CaO in 1 liter of water; and the mixture designated Al(OH) 
was prepared by mixing two solutions each of 900 cc., the one 
containing 26 grams of AlCl; and the other 30 grams of CaO 
(slaked as for the Bordeaux mixture). Тһе clay suspension 
consisted of 90 grams of fine air-dried clay in 1 liter of water. 
The lime-sulphur employed was the usual 1-25 strength. 
EXPERIMENTAL DATA AND DISCUSSION 
It will be observed from the brief review of earlier work 
that the evidence regarding the effect of Bordeaux mixture 
оп the transpiration rate is inconsistent. А majority of the 
observers adopt the view that the effect of this surface film 
is to reduce the transpiration. On a priori grounds this view 
would seem to be logical, since it would indicate a water conser- 
vation to which, in dry seasons at least, the plant might respond 
with increased vitality and yield. Nevertheless, it was believed 
that the experimental evidence at hand was of insufficient scope 
to establish this view of it. Contrary to expectations, all of 
our more important experimental evidence and observations 
are antagonistic to the a priori assumption as applied to the 
effects of Bordeaux mixture. 
Potometer experiments.—In attempting to secure leaves sat- 
isfactory for the work, some incidental observations were made 
which are of interest. Тһе work was begun during the winter, 
so that greenhouse-grown plants alone were available. Fur- 
thermore, in this work with potometers, Bordeaux mixture 
alone has been used by us. "Testing leaves of squash (Cucur- 
bita sp.), Pelargonium zonata, and Phytolacca, also shoots of 
potato and 1тезсепе, as to their behavior under the conditions 
required, it was found that of comparable leaves, sprayed and 
unsprayed, invariably the sprayed leaves were the first to wilt. 
This might be attributed either to an injurious action of the 
spray or to a greater water consumption. That the last men- 
tioned is the more probable explanation finds confirmation 
through a special observation on the potato. Owing appar- 
ently to some stoppage of the vascular system, abscised potato 
shoots are unsuitable for potometer work, wilting in a com- 
paratively short time even when cut under water; and sprayed 
potato shoots wilt more quickly than unsprayed, thus pointing 
