476 



The very interesting results of experiments made by G. Kraus^ to 

 explain sabre growths and other tree forms, induced by the wind, are of 

 great importance. If a fresh growing shoot of an herbaceous or woody 

 plant be bent so that its tip overhangs, the concentration of the cell sap on 

 the convex side has become more concentrated. The increased sap concen- 

 tration of the convex side is due to an essentially higher sugar content. 

 This sugar is newly formed when the shock takes place. This noteworthy 

 peculiarity is exhibited not only by the trunk and branches, but also by the 

 half grown and fully grown petioles. The sugar formation, however, is 

 not connected with the deformation but depends on the motion as such, and 

 frequently when the sugar is formed, the free acid disappears. Ferruza- 

 observed in palms and succulents that such interference increased the trans- 

 piration ; after VViesner" and I'.berdt* had shown that the wind hastened the 

 transpiration. It was found by Kohl'' and Baranetzky** that even very 

 slight interference would increase the amount of evaporation. Reference 

 should be made to Burgerstein in regard to further literature". 



The local distribution of the sugar warrants the conclusion that it is a 

 preliminary step, if not a direct one, in the formation of cellulose in the 

 plant's metabolism, and it should be stated that, with the increased sugar 

 formation in the parts of the plant moved by the wind, the formation of 

 cellulose and the development of the cell wall will be hastened. It is a 

 comparatively rare occurrence that plant tissues remain in the stage of their 

 development in which sugar is formed. More frequent is the process, 

 especially in growing shoots, that the sugar disappears to the same extent 

 as the cells become thicker walled. We will, therefore, scarcely go astray 

 in stating that deformations, resulting from the action of the wind, are more 

 stable, since the convex side of the bend forms sugar and cellulose more 

 easily; hence its growth is completed sooner. If we consider that the place 

 bent is more favorable for the action of light and warmth, then the early 

 termination of the period of cell elongation is really a matter of course. 

 The branch hardens sooner and does not grow so long; hence, therefore, 

 the compact structure of the windward side and the slender, almost whip- 

 like branch formation on the side protected from the wind. 



No more thorough discussion is necessary to understand the fact that , 

 seed beds and young plantations in light soils may at times be blown to 

 pieces, that surface soil may often be blown away and become sterile because 

 of the sudden imprudent removal of protective strips of forest and that 



1 Kraus, G., tlber die Wasserverteilung in der Pflanze, II. Der Zellsaft und 

 .seine Inhalte. Sep.-Abdr. aus d. Abhandl. d. Naturf.-Ges. zu Halle, Vol. XV; cit. 

 Bot. Zeit. 1881, p. 389. 



2 Ferruzza, G., Sulla traspirazione di alcune palmi, etc.; cit. Bot. Jahresber. 

 1899, II, p. 124. 



3 Wiesner, Jul., Grundversuche iiber den Einfluss der Luftbewegungen auf 

 die Transpiration der Pflanzen. K. K. Akad. d. Wissensch., Wien, 1887, Vol. 96. 



4 Eberdt, O., Transpiration der Pflanzen und ihre Abhangigkeit von ausseren 

 Bedingungen. Marburg 1889, p. 82. 



s Kohl, F. G., Die Transpiration der Pflanzen. Braunschweig 1886. 

 6 Baranetzky, tlber den Einfluss einiger Bedingungen auf die Transpiration der 

 Pflanzen. Bot. Zeit. 1872. 



~ Burgerstein, Transpiration der Pflanzen. 1904. 



