322 Forestry Quarterly. 



Referring to the biological value of leaf fall, the writer refers 

 to Wiesner's classification according to causes into summer leaf 

 fall, heat leaf fall, shoot leaf fall, autumn leaf fall and frost leaf 

 fall ; the first caused by insufficient light reaching the interior of 

 crowns, the second by drouth, the third caused by the sprouting of 

 dormant buds at the base of leaves, the last two by reduction of 

 transpiration and respiration. In all cases except frost leaf fall, it 

 is a natural reaction to exterior conditions and of advantage to the 

 life of the plant. 



The loss of foliage in the autumn reduces damage from wind 

 and snow. The fallen litter enriches the soil with minerals, espe- 

 cially carbon from the air, as well as nitrogen contained in organic 

 substance. By humification the physical condition of the soil is 

 improved and the leaf-litter protects the soil against radiation and 

 frost. In early spring the sun can reach all the buds in the leafless 

 crown and expedite their awakening, the summergreen trees hav- 

 ing in this respect an advantage over the wintergreen, whose buds 

 are confined to the periphery of the crown. 



Wirkung des Frostes auf den Laubabfall. Schweizerische Zeitschrift fiir 

 Forstwesen, April, 1909, pp. 105-112. 



The old doctrine that germination of seeds 

 Germination is promoted by the absence of light has been 



and dispelled by the investigations of Kinzel, 



Dormancy. who has demonstrated with a number of 



plants that the very opposite is true. De- 

 layed germination or dormancy, the same investigator finds not 

 necessarily to be due to the character of the seed coat, but pos- 

 sibly to the character of the embryo. 



Lichtkeimung. Berichte, Deutsche Botanische Gesellschaft, 1908, pp. 

 631-645. 



SOIL, WATER AND CLIMATE. 



A belated consideration of the proceedings 



Forests of the Navigation Congress at Milan, in 



and : 9°5^ ca hs forth a discussion by Buffault of 



Water Flow. the evidence reported at the Congress and 



elsewhere of forests on waterflow in answer 



to the position taken by Rabot, Secretary of the French Geo- 



