635 



themselves, or lean somewhat down hill, and slowly continue growth. 

 Usually growing branches are found only on the side toward the valley, 

 since the rolHng snow masses have broken off those of the opposite side. 

 In deciduous forests, deformed bushes develop, because of the tearing out 

 of the roots or trunks ; they look as if produced by the grazing of wild 

 animals. 



The influence of the snow covering, and of the accompanying frosts on 

 seeds has been mentioned already in an earlier chapter. In regard to 

 changes in temperature in the soil, reference should be made to Wild and 

 \Vollny\ The ice-water, produced by the melting of the snow, can not be 

 without effect, as soon as it reaches green meadows and seeded fields. 

 Kiister-, for example, has shown that, as a result of cooling with ice-water 

 in the chlorophyll grains of Funaria leaves, a vacuole formation is started 

 which results in the green pigment's lying at the edge of the vacuoles in the 

 form of crescents. 



Ice coating and icicles. The injuries from ice formed on trees are 

 more rare. A quickly melting coating of smooth ice is usually considered 

 non-injurious. Nevertheless, in general many growers ascribe the produc- 

 tion of blasted specks to the deposition of ice on smooth barked branches 

 and trunks. If, with Nouel, the production of smooth ice is considered 

 as the solidifying of the rain drops due to the impact of striking the tree, the 

 drops having already been cooled below zero degrees, it can be assumed 

 that the cold of the ice acts injuriously. From the experiences collected 

 from artificial frost experiments, I am of the opinion that the smooth ice 

 covering can act injuriously, because of changes in tension in the ice-covered 

 tissue. It may be proved, in very light spring frosts, that clefts arise in 

 the bark tissue of herbaceous shoots without any extensive browning of 

 the cell; therefore, without the chemical action of the frost having made 

 itself felt. Such injuries to the tissues are also possible from smooth ice, 

 if it remains for some time on the plant and especially if it outlasts the 

 fluctuations in temperature frequently occurring with the formation of 

 smooth ice. 



It is possible to distinguish from the usual formation of smooth ice, 

 the ice and mist coverings which might be compared with snow pressure 

 because they depend upon different processes of formation. As character- 

 istic of the phenomenon, we will consider a description by Breitenlohner", 

 who made extensive observations. On January 2y, 1879, precipitation 

 began in the middle of the day, in A. forest near Vienna with a complete 

 cessation of wind and with misty weather, under an increasing air pressure 

 and low temperature. This precipitation was half way between a drizzle 

 and mist and soon hardened to smooth ice. A one-sided ice covering 3 to 



1 Bot. Jahresber. 1898, I, p. 584-85. 



2 Kiister, E., Beitrage zur Physiologie u. Pathologie der Pflanzenzelle. Z. f. 

 allg-em. Physiologie 1904, Vol. 4. 



3 Breitenlohner, Der Eis- und Duftanhang im Wiener Walde. Forsch. auf d. 

 Gebiete d. Agrikulturphysik 1879, p. 497. 



