1 900- 1 . ] 



Effects of W.a.ter on Foliage Leaves. 



309 



the mustard. This method of weed extermination has been carried on 

 successfully, it is said, in England and France, but in matters 

 pertaining to the farm there is usually very little, if any (Experi. 

 Station Bulletins ref Chapter II.), literature pertaining to the 

 subject. The amount of liquid used per acre at Ottawa was of 

 CUSO4 solution fifty gallons, made up of two pounds of CuSO^ to 

 ten gallons water No observations seem to have been made as to the 

 actual effect upon the crop, though it is inferred that the barley crop 

 did not suffer materially. 



The experiments just referred to, together with those performed by 

 the writer (tobacco spotting) leave no room for doubt whatever that 

 solutions are absorbed by plants. The most important part, however, of 

 this very interesting subject, as has been observed by several writers, to 

 whom reference has been made in Chapter II., is the fact that these 

 solutions which will kill one plant may actually promote growth in 

 another. No experiments were performed by the writer with this end 

 in view. 



The main objects of the following experiments were to ascertain 

 whether solutions are absorbed by leaves (the test employed by 

 Boussingault was adopted), and to determine the ph}^siological effect. 



Series I. 



Effect of solutions applied to leaf surfaces in the form of drops. 

 July, 1900, leaf Ampelopsis ; solution applied to lower side. Column i, 

 solution used ; 2, absorbed* ; 3, dry, moist or crystals ; 4, dark ring ; 

 5, colour of spot ; 6, less apparent effect on the lower surface of the leaf. 

 The strength of the solution used, excepting the nutrient solution and 

 the copper sulphate, was m/4. The copper sulphate was m/56. 



* Absorbed if no deposit remained after evaporation. 

 6 



