CHLOROSIS 37 



the phosphate and chlorate) do not affect the cure so readily. 

 Spring (May) months are the most appropriate time for this 

 operation. By this method I have effected a permanent 

 cure on many hundreds of trees of different varieties, not 

 excepting coniferous or evergreen trees. The deforming 

 anthracnose of the grape-vine rapidly disappears under the 

 influence of sulphate of iron, the leaves acquiring their 

 normal size and colour. In other experiments of this 

 internal method of nourishing the plants, not directly through 

 the roots, by means of various combinations of salts, dry or 

 in solution (using for this purpose a small and very simple 

 apparatus) I succeeded in increasing their size and improving 

 their colour, thus effecting a cure. 



Mokrzecki, S., Gard. Chron., Jan. 16, 1904, where refer- 

 ence to further literature by the same author is given. 

 Viala, P., Malad. de la Vigne, p. 430 (1893). 



Contagious chlorosis. Baur has shown that chlorosis of a 

 contagious nature exists in certain members of the Malvaceae, 

 also in Ligustrum and Laburnum, and is probably of wide- 

 spread occurrence. The cultivated variegated mallows were 

 derived from a form of Abutilon striatum called A. Thomsoni. 

 This plant transmits its variegated condition by grafting. 

 Baur discovered that if the leaves are removed from a 

 variegated plant, or if the shoots bearing leaves are removed, 

 and the plant is kept in the dark, the new shoots produce 

 only very few variegated leaves, and if those are removed, the 

 plant remains permanently green in the light, unless it is 

 again infected by grafting scions of a variegated plant. If 

 latent axillary buds of the old parts produce variegated leaves 

 the whole plant is quickly infected. When scions of the 

 immune A. arboreum are grafted on the infected A. Thomsoni 

 they grow readily but do not become infected ; whereas if 

 scions of a susceptible kind are in turn grafted on the A. 

 arboreum of the previous experiment, they become infected, 

 thus proving that the virus can travel unchanged through the 

 intermediate piece of A. arboreum. Shoots bearing green 

 leaves that are immune to the disease sometimes appear on 

 A. Thomsoni. If one of these shoots is grafted on a varie- 

 gated plant the scion continues to produce green leaves. If 

 in turn a susceptible scion is grafted on to the immune 

 branch, its leaves are variegated, showing that the virus 



