PERIODICAL LITERATURE 

 BOTANY AND ZOOLOGY 



In a volume of 166 pages Klebs on the 

 Rest basis of painstaking investigations, espe- 



Period cially on beech, demoHshes the theory that 



in Trees a rest period is a necessity for all trees, 



and that the variable period is a matter of 

 predisposition and adaptation to climatic conditions, which by 

 outside influences can be somewhat varied but not entirely over- 

 come. By means of electric light of from 200 to 1,000 candle 

 power, Klebs could force beech plants and twigs to either sprout 

 or remain quiescent at will. The shoots so forced either grew 

 continuously from November till spring with more leaves than 

 were originally found in Anlage, or grew more or less intermit- 

 tently. From these and other experiments, the author has 

 reached the conclusion that above all the relation between supply 

 of carbohydrates and nutritive salts to the vegetation points 

 decides whether rest or growth results. This explains also the 

 influence of light. Under illumination respiration is always more 

 intensive than carbonic acid assimilation, so that the nutritive 

 salts, which otherwise would be utilized in the latter process, 

 could go to the buds and stimulate them into activity. 



In nature the budding out in spring, with beech at least, is due 

 to increasing light together with satisfactory supply of salts. The 

 quiescent state of buds in summer arrives through the competi- 

 tion of leaves and cambium for the salts : the accumulation of 

 assimilated food impedes the growth energy of vegetative points. 

 The August shoot is a victory of strong light available to specially 

 favorably located buds. 



Since in the experimental plants spring wood and summer 

 wood was formed alternately, the author inclines to Hartig's and 

 Wieler's theory of this variation as being due to variations in 

 the nutrition of cambium cells, and proposes a change of terms to 

 wide and narrow wood (Weit- und Engholz). He recognizes, 

 however, an inherited structure of wood of different species. 



Ober das Treiben der einheimischen Bdume, speziell der Buche. Review. 

 Zeitschrift fur Forst- und Jagdwesen, March, 1915, pp. 211-212. 



382 



