Page 717. For the diseases of the horseradish, we have referred to 

 our detailed article in the Zeitschrift fiir Pflanzenkrankheiten, 1899, p. 132. 

 It is stated there, "The forms of disease mentioned appear to me on this 

 account only as a great increase of a wide-spread tendency to gummy 

 degeneration . . . because in the production of the masses filling the 

 vessels the liquification of the secondary membranes cooperates in certain 

 cases." This theory has been shared recently by A. Schleyer (Der Anbau 

 des Merrettichs usw. cit. Biedermanns Zentralbl. f. Agrik., Part 8, 1908). 

 He says, "In my opinion, the turning black is conditioned by the fact that 

 the Pentosane and the sugar in the horseradish degenerates into gum." 

 Experiments also confirm the theory that lime should be used as a remedy 

 (since humic acid is often present in the soil). When the plants v/ere 

 cultivated in nutrient solutions, some of which were made up with calcium, 

 others without it, the gummy degeneration of "the sugar" could be proved 

 very soon in the plants which did not have calcium. 



Page 718. The subject of the injuries due to the gases of smoke and 

 other industrial waste substances is beginning to be separated as a special 

 branch of general pathology and is represented by a special publication. 

 Since 1908, there has existed the "Sammlung von Abhandlungen iiber 

 Abgase und Rauchschaden" edited by Prof. Dr. Wislicenus, who has already 

 given in the first part a comprehensive description "Ueber die Grundlagen 

 technischer und gesetzlicher Massnahmen gegen Rauchschaden." 



Recent investigations by Haselhofif (Z. f. Pflanzenkrankh. 1908) treat 

 of the action of sulfurous acid on soil. The experiments show that vege- 

 tation is not injured if the soil contains such amounts of decomposable 

 bases (especially calcium) that the sulfuric acid, formed from the supplied 

 acid, is combined. The case described by Wieler of soil impoverishment in 

 the presence of free acids in the soil may be found very rarely (perhaps in 

 forest soils). If, on the other hand, sulfurous acid is introduced into the 

 soil during the growth of the plants so that it shows an acid condition, dis- 

 turbances in growth become clearly noticeable. In soils continuing copper, 

 the copper is carried over into easily soluble compounds of the sulfurous 

 acid and this dissolved copper can then become injurious to vegetation. But 

 even here calcium carbonate helps since it arrests the dissolving action of 

 the acid. 



Page 761. The occurrence of a disadvantageous effect of Bordeaux 

 solution on the yield, which we first observed, has been confirmed by recent 

 experiments of v. Kirchner (Z. f. Pflankrank., Part II, 1908). The author 

 takes the older literature also into consideration. Probably the shading 

 action of the solution should be made responsible for the lessened yield. 

 This would explain also the rapid turning green of leaves with strong 

 illumination. The greater amount of starch is not to be ascribed to 

 increased assimulation but to a decreased removal of the assimilates. 



