68 JOHN W. SHIVE AND WILLIAM H. MARTIN 



been considered in this connection by Schander,^ who suggests 

 that decreased rates of transpiration from plants sprayed with 

 Bordeaux mixture are to be expected, since the spray material 

 must exclude from the leaf certain rays which in the unsprayed 

 leaf tend to accelerate the process of transpiration. An attempt 

 to verify this theoretical conclusion by a study of leaf tempera- 

 tures met with but little success. 



As early as 1894, Frank and Krliger,^ as the result of investi- 

 gations in which they employed quantitative methods, reached 

 the important conclusion that Bordeaux mixture, when applied 

 to the leaves of plants as a spray, exerts an accelerating influence 

 on the rates of water loss by transpiration. Very convincing 

 evidence in support of these observations has recently been 

 presented by Duggar and Cooley^- ^ in two publications. These 

 authors have demonstrated quantitatively that the normal 

 rates of transpiration of abscised leaves of the castor bean {Ricinus 

 communis, L.) are very materially increased by a surface film 

 of Bordeaux mixture. With potted plants of the tomato {Ly- 

 copersicum esculentum, Mill.) and of the potato {Solayium tubero- 

 sum L.) they have shown also that as a result of an application of 

 this spray mixture the transpiration rates were markedly in- 

 creased in comparison with the rates from similar unsprayed 

 plants. In a series of quantitative experiments which have 

 just been published, Martin^ has confirmed the work of Duggar 

 and Cooley with abscised castor bean leaves and with potted 

 tomato plants, and has extended his tests to include eight species 

 of abscised leaves and five species of potted plants. 



2 Schander, R., Ueber die physiologische Wirkung der Kupfervitriolkalk- 

 bruhe. Landw. Jahrb. 33: 517-584. 1914. 



' Frank, A. B. and Kriiger, F., Ueber den direkten Einfluss der Kupfervitriol- 

 kalkbruhe auf die Kartoffelpflanze. Arb. d. deut. landw. Ges. 1894: 1-46. 



^ Duggar, B. M. and Cooley, J. S., The effect of surface films and dusts on 

 the rate of transpiration. Ann. Missouri Bot. Gard. 1: 1-22. 1914. 



* , The effect of surface films on the rate of transpiration: Ex- 

 periments with potted potatoes. Ann. Missiouri Bot. Gard. 1: 351-356. 1914. 



® Martin, W. H., The influence of Bordeaux mixture on the rates of transpira- 

 tion from abscised leaves and from potted plants. Jour. Agr. Res. 7: 529-548. 

 1916. 



