826 EXPERIMENT STATION RECORD. 



Of the observed effects of the poisons the more important may be listed as 

 follows: (1) Accumulation of the toxic substances, particularly in the older 

 leaves, the chlorophyll of which is in part destroyed or the laminse are in part 

 dried out by the treatment; (2) a checking of the growth of the young shoots 

 by cobalt; and (3) development of parasites (otherwise too weak to invade the 

 vigorous plant) in the leaves the energy of which has been lowered by the in- 

 jurious action of sodium chlorid. Ascoehyta olece, Stictis panissei, Phyllosticta 

 insulana, Coniothyriuin olece, and Septoria olccc are mentioned as being favored 

 by the weakening influence of the salt. In this connection suggestions are made 

 as to the probable effects of soil solutions in nature in favoring parasitic and 

 physiological diseases, and as to the study of such natural conditions. 



Winterkilling and smelter injury in the forests of Montana, G. G. Hedg- 

 cocK (Torreya, 12 (1912), No. 2, pp. 25-30). — The author has made an extended 

 study of the winter injury of trees in the region about Anaconda, Mont., com- 

 paring this injury with that produced by smelter fumes from the large smelters 

 situated nearby. 



In both cases the needles of the pine trees are reddened, but the smelter 

 injury causes a brighter color and does not so often kill the whole leaf as the 

 winter injury. In the case of lodgepole pine and of Douglas fir trees the 

 winter injury in the acute form killed not only the leaves but often the terminal 

 buds and twigs, and the whole tree died the following season. In the acute 

 form of smelter or sulphur dioxid injury the leaves die more gradually, and 

 the terminal buds are usually the last portions of the tree to show injury. In 

 the less acute form the injury by smelter fumes causes a slow defoliation of 

 coniferous trees, while in the case of winter injuiy only a few terminal buds or 

 twigs and the leaves are affected. A third form of smelter injury consists of 

 a gradual premature defoliation of the trees, accompanied by slight chlorosis 

 and change of appearance in the leaves. 



• In all the forms of smelter injury the effect on the annual rings is very 

 pronounced, the size of the rings being gradually reduced, while in the case of 

 winter injury there is usually a sudden stopping of growth. In case the winter 

 injury was less severe but little growth was noticed in the year following the 

 injury, followed by an increased growth the subsequent season. 



Great difference in the ability of conifers to withstand the effect of smelter 

 fumes is noted, and the ability of trees to withstand the winter injury is not 

 in the same ratio as that of their resistance to smelter fumes. Trees in the 

 inner portion of the smelter zone bear few if any seed, and reforestation is not 

 progressing in this region, while outside of the smelter zone, where only winter 

 injury has occurred, reproduction is said to be gradually taking place. 



Investig'ations on wound stimulation and wound closure in plant organs, 

 O. Schneider-Orelli (CentU. BaU. [etG.^, 2. Aht., 30 {1911), No. 16-18, pp. 1,20- 

 1,29). — Experiments carried on with apples, pears, wounded potato tubers, and 

 those attacked by fungi are reported. 



In apples and pears plucked unripe, as well as in old tubers, it is claimed 

 that the ability to supply a wound periderm ceases before the close of the trau- 

 matic respiration stimulation. At low temperatures apples form no cork over 

 the wounded surface and permit infection thereat. Normal wound periderm 

 forms at the cut surface of potatoes without the participation of deeper-lying 

 tissue. Infected tubers usually respire more vigorously than sound ones, but 

 this appears to be referable to the stimulation of the host cells much more 

 than to the strong respiration of the parasite. 



Endotrophic mycorrhiza of the horse chestnut, P. Jaccard {Bui. Sac. Vaud. 

 8ci. Nat., 5. ser., ^7 {1911), No. 113, pp. XXV-XXVII ; abs. in Internat. Inst. 

 Agr. [Bome}, Bui. Bur. Apr. Intel, and Plant Diseases, 2 {1911), No. 7, pp. 



