SUPPLEMENT. 



Page 307. New investigations on Chlorosis have been published by 

 Molz (Die Chlorose der Reben, Jena 1907, G. Fischer). In confirmation of 

 the theory, w^hich we have expressed, a lack of oxygen for the roots may 

 actually be considered as the cause. On this account low positions, where 

 water flowing from higher ground can collect, are the most dangerous. In 

 heavy soils the development of the root system suffers from this. Lime 

 itself cannot produce chlorosis but soils rich in lime cause especially the 

 death of the roots, since they are often very fine grained and can produce an 

 alkaline reaction. Therefore, we may speak of a calcium chlorosis. Con- 

 tinued drought, as well as cold, can also produce chlorosis. Worth consid- 

 eration is Molz's theory that the weak constitution of a chlorotic plant can 

 be carried over by the wood used for propagation. The disease can either 

 be inherent in the cuttings from the beginning, or "certain disadvantageous 

 circumstances from outside, resulting from an inherited, strong predisposi- 

 tion, can cause the production of the icteric phenomenon and its results." 

 A permanent cure cannot be brought about by iron sulfate. At best only 

 the symptoms will be removed and it is probable that the greening of the 

 leaves is not caused by the iron but by the sulfuric acid. 



Page 335. Molz studied dropsy in grape cuttings (Bericht der Kgl. 

 Lehranstalt zu Geisenheim a. Rhein, 1906). The cuttings had stood for 

 some time in damp soil. They were swollen up like'clubs in different places, 

 thus splitting lengthwise the outermost tissue layers. A white, spongy tissue 

 became visible in the gaping wound, which consisted of hypertrophied bark 

 cells. Molz considers the disease, which is not uncommon in moist vine- 

 yards, to be identical with that in Ribes aureum described by Sorauer. 



Page 345. Black specks are found in the one-year-old shoots of T'itis 

 vinifera and, appear somewhat raised. Molz (Centralblatt f. Bakt. II, Vol. 

 XX, 1908, Nos. 8 und 9) describes these as small, round knobs of a blunt, 

 conical form ("bark warts"), which may be considered as a compensation 

 for the lenticles not found in Vitis vinifera. Each one has a stoma on its ' 

 tip which dries up rather early. This drying extends to the neighboring cell 

 groups and advances until halted by the formation of a protecting cork 

 layer. The stronger and better nourished the tissue is the more quickly the 



