1905.] Copper Sulphate Solutions on Plants. 413 



Stations, the education of dairymen, and the promotion of Dairy 

 Co-operative Societies. 



The influence ot copper and copper salts on plant life has 

 formed at different times the subject of many experiments. It 



Copper Sulphate ce ^ s both of the lower and higher plants, 

 Solutions on but in 1885 Millardet showed also that an 



copper, in the form known as the Bordeaux mixture, was an 

 excellent fungicide — a discovery which was of special importance 

 as affording a means of combating various injurious fungi on 

 the leaves of cultivated plants. This, as is well known, is a 

 mixture of sulphate of copper and calcium hydrate, which is 

 distributed on the leaves in the form of a fine spray. Spraying 

 of this kind has been observed under some circumstances to 

 exercise a certain effect on the leaves and on the development 

 of healthy plants, and in a lengthy article in the Landivirt- 

 schaftliche JaJubiicJier* Herr Richard Schander deals with the 

 question in its different aspects, confining his attention, however, 

 exclusively to the effect of the copper solution on the living 

 plant and not on the fungi. 



Bordeaux mixture has been considered by various investiga- 

 tors to exercise a beneficial influence in the following way : (1) 

 the leaves appeared firmer, more robust and thicker ; (2) they 

 were of a deeper green colour ; (3) the assimilation of the leaves 

 was increased ; (4) the amount of transpiration was changed ; 

 and (5) the duration of vegetation was lengthened. Other investi- 

 gators, however, have arrived at a different conclusion, so far as 

 general effect is concerned, and have showed that the Bordeaux 

 mixture checked the development of the plant and resulted in 

 a smaller yield. 



By far the greater part of the experimenters attributed the 

 effect of the Bordeaux mixture to the copper hydrate. Accord- 

 ing to one view the copper salts, without penetrating into the 

 leaf, exercise a stimulating influence on the cells. Another view 

 is that the smallest copper particles, partly with and partly 

 without assistance from the cell sap, penetrate the cuticle 



Investigations 

 into the Effect of 



was early known that copper in its soluble 

 combinations was poisonous to the living 



Plants. 



insoluble or hardly soluble combination of 



* Vol. XXXIIL, 1904. Part 4— 5. 



