30 
Hilgard,! Hoffmann,? Braungart,* Roux,‘ and a great many others 
have observed that certain species of plants fail to make a normal 
erowth on calcareous soils or refuse to grow at all. On the other 
hand there are certain plants which only reach their fullest develop- 
ment on soils that are rich in calcium carbonate. 
Although it is so well known that certain plants become chlorotic 
when grown on calcareous soils, the way in which the lime acts in 
producing the chlorosis is not well understood. As long ago as 1843 
Eusébe Gris showed that by treatment with ferrous sulphate chlorotic 
plants become green. Much later Sachs* treated many chlorotic 
plants successfully with ferrous sulphate. A great deal of work has 
been done in France and Germany on the treatment of chlorotic 
grapevines with ferrous sulphate and other compounds of iron.® 
These treatments where they have not completely restored the normal 
ereen to the leaves have markedly diminished the chlorosis. Hiltner’? 
has restored the green color to chlorotic lupines growing on a strongly 
calcareous soil. 
That the effectiveness of the ferrous sulphate in overcoming the 
chlorosis is due merely to the iron was well shown by Guillon,’ who 
treated chlorotic grapevines with ferrous sulphate, sulphuric acid, 
sodium sulphate, and with the tannate, malate, and citrate of iron. 
Only the iron compounds were effective. Hiltner’ in a similar 
manner. confirmed this in his treatment of lupines. 
The opinion of those who have treated successfully the chlorotic 
plants with ferrous sulphate and ferric chlorid is, in general, that 
the chlorosis of the plants is caused by a lack of iron in the plant, the 
plant being unable to take up the necessary amount of iron in cal- 
careous soils. However, comparative analyses made of chlorotic 
and green leaves and wood of the grapevine by Schulze® show that 
the healthy plant contains much more potash than the chlorotic plant. 
Mach and Kurmann’ obtained similar results. Others, therefore, 
including Sorauer™ and Euler,'? have the opinion that the chlorosis 
is largely induced by a lack of potash. 
1E. W. Hilgard. Soils. New York, 1906. Proc. Soc. Prom. Agr. Sci., 7 (1886), p. 32; Forsch. Geb. 
Agr. Phys., 10 (1888), p. 185. 
2H.Hoffmann. Landw. Vers. Stat.,13(1871), p. 269. 
3 R, Braungart. Jour. Landw., 28 (1880), p. 155. 
4J. A.C. Roux. Traité des Rapports des Plantes avec le sol et de la Chlorose Végétale. Montpellier and 
Paris, 1900. 
5 Loc. cit. 
6 Luedecke. Ztschr. Landw. Ver. Grossherzogthums Hessen, 62 (1892), No. 41, p. 333; 63 (1893), No. 2, p.9- 
A. Bernard, Prog. Agr. et Vit., 18 (1892), pp. 36-42. J.M. Guillon, Prog. Agr. et Vit., 26 (1896), pp. 606-608, 
A. Menudier, Jour. Agr. Prat., 60 (1896), II, pp. 157, 158. J. Dufour, Ber. Schweiz. Bot. Gesell., 1892, No. 
2, pp. 4446. 
7L. Hiltner. Prakt. Bl. Pflanzenbau u. Pflanzenschutz, n. ser., 7 (1909), Nos. 2, 3, 5. 
8J.M. Guillon. Prog. Agr. et Vit., 23 (1895), p. 653. 
9E. Schulze. Centbl. Agr. Chem., 2 (1872), p. 99. 
10 Centbl. Agr. Chem., 1877, p. 58. 
11 Paul Sorauer. Handbuch der Pflanzenkrankheiten, Berlin, 1909, 3. ed., vol. 1, p. 310. 
2H. Euler. Grundlagen und Ergebnisse der Pflanzenchemie. Braunschweig, 1909, pt. 3, p. 153. 
[Bull. 11] 
