Periodical Literature. 193 



Under an old oak stand the conditions were found still more 

 striking. In the soil layer 



down to 4 inches, 1545 lbs. 



4 inches to 12 inches, 2610 lbs. 



12 inches to 24 inches, 1642 lbs. 



24 inches to 32 inches, 732 lbs. 



6529 lbs. 

 per acre were found. 



Lately it has been found that frost reduces the nitrogen-gath- 

 ering capacity of soil bacteria, hence, clearing is liable to bring 

 damage in this direction. Thomas slag and phosphoric fer- 

 tilizers increase it. 



That plants may take up nitrogen directly through the leaves 

 has been held by various botanists. Lately, Jamieson had found 

 various trichomes on foliage to be organs specially adapted to 

 this purpose. He found such hairs of various shapes in Acer 

 campestre, Tilia, Ulmus, Sorbus, Fagus, Abies concolor; the 

 presence of nitrogen in these organs and their presence in the 

 youngest parts, which are richest in nitrogen, is the argument for 

 their functions. 



Last year, two Hungarians, Zemplen and Roth, of the Forest 

 Experiment Station, have published, illustrated by many colored 

 plates, their findings in Erdeszeti Kiiserletek, Heft 1 and 2, 

 which seem to confirm Jamieson's claim. 



A long series of deciduous leaved trees showing these trichomes 

 in a variety of shapes, mostly on the leaf stems and nerves, but 

 also on youngest shoots and fruits was investigated. Conifers 

 also were found to have these organs, but the nitrogen reactions 

 were weaker. The life and function of the hairs on deciduous 

 leaves is shorter and, therefore, perhaps more intensive. On the 

 fruit of Juglans regia the hairs are especially rich in nitrogen. 



The question remains open whether this nitrogen comes from 

 the air or other parts of the plant. Against the latter assumption 

 argues the fact that the albumen reaction does not begin until a 

 certain stage of development of the trichome is reached, and then 

 always in its head, only later in the foot. 



Centralblatt f. d. g. Forstwesen, February, 1909, pp. 89-92. 



