THE EFFECT OF BORDEAUX MIXTURE ON THE 
RATE OF TRANSPIRATION 
B. M. DUGGAR 
Physiologist to the Missouri Botanical Garden, in Charge of Graduate 4579 
Professor of Plant Physiology in the Henry Shaw School of Botany o 
ashington University 
р W. W. BONNS 
Rufus J. Lackland рацо, ги the Henry Shaw School of Botany of 
Washington University 
Two earlier reports! from this laboratory seemed suffi- 
ciently to establish the point that a film of Bordeaux mixture 
inereases the rate of transpiration of excised leaves of the 
castor bean, and likewise of potted tomato and potato plants. 
It was further indieated that other surface films, and to a 
slight extent dusts, may produce a similar, though on the 
whole lesser, accelerating effect. Nevertheless, it was felt 
that this work left incompletely answered questions relating 
both to the immediate and final effeets of the spray, as well 
as to the relation of the acceleration found to night and day 
conditions, or to changes of environmental conditions in gen- 
eral Again, it seemed eminently desirable to construct and 
employ in this work a rotating table, or transpirotaplane, by 
means of which it might be hoped to eliminate such errors 
as might arise from differing transpiration rates induced 
through the position of the plants in the different in- 
tervals, whether the plants observed were in the greenhouse 
or in the open. In the earlier experiments it had not been 
possible to take sufficient cognizance of these points, but im- 
mediately upon the presentation of the reports referred to 
above, further experiments were begun leading in the direc- 
tions indicated. A variety of considerations prevented a 
prompt conclusion of this work. Meanwhile, there has ap- 
peared a paper by Martin? affording interesting and definite 
Duggar, B. M., and Cooley, J. S. The effect of кеде: films and dusts on 
the rate of transpiration Ann. Mo. Bot. Gard. 1: 1-22. pl. 1. 1914; The effects 
of surface film "E А of transpiration: experiments with potted potatoes. 
Ibid. 351-356. pl. 18. 
? Martin, W. H. ms Am of Bordeaux mixture on the rates of transpiration 
from abscised leaves and from potted plants. Jour. Agr. Res. 7 : 529—548. 1916. 
ANN. Mo. Вот. GARD., VOL. 5, 1918 (153) 
