26 AMERICAN VINES. 



later on appeared, but in lesser intensity, in the row treated 

 with 5^ ounces. The row treated with the crystals of 

 sulphate of iron did not appear to be affected in any way. 

 As for the non-treated row, it became yellower. 



All these experiments prove that sulphate of iron has 

 a .marked action on the reappearance of the green colour, 

 which is so much the more marked as the quantity applied 

 is greater. 



In crystals, its efficacy is much less. However, in the 

 south of France, good results were obtained, especially after 

 a few years use of sulphate of iron in that form in great 

 quantities. Two and a quarter Ibs. per vine, at least, should 

 be applied, and even with that large amount good results do 

 not always follow. 



Sprayed on the leaves in the proportion of i per cent, dis- 

 solved in water, sulphate of iron brings about the disappear- 

 ance of chlorosis. Eusebe and Arthur Gris were the first to 

 establish this definitely. Narbonne was able to diminish by 

 this means the intensity of chlorosis in a large vineyard near 

 Bize (Aude). We arrived at the same results also. 



Gouirand recently experimented with numerous salts of 

 iron in chalky soils of the Charentes, where chlorosis attains 

 a very serious form. These salts were sulphate, tartrate, 

 malate, acetate, tannate, sucrate, and carbonate of iron, 

 applied by spraying on the leaves. The four first salts gave 

 positive results, the three last had little or no action. The 

 sulphate seemed to be the most active. 



Many horticulturists and botanists attribute the reappear- 

 ance of the green colour to the fact that the leaf contains 

 tannin, which combining with the iron forms tannate of iron 

 of blackish-green colour. 



This explanation is not plausible; it suffices to examine a 

 treated leaf under the microscope to ascertain that it does 

 not take place, and that the reappearance of the green colour 

 is due only to the reappearance of chlorophyll. Arthur Gris 

 showed this long since (Ann. Scienc. not. 1857. 4th series. 

 Vol. VII. , p. 179) by attentively following the developments 

 and multiplications of the chlorophyll corpuscles and their 

 colourations (pi. V. to X.). What is then the action of the 

 salts of iron on chlorophyll ? 



Eusebe and Arthur Gris ascertained in etiolated plants 

 the phenomena of the developing and colouring of chloro- ' 

 phyll corpuscles under the direct and intimate action 



