Periodical Literature. 325 



blue beech, has become poor, crippled underbrush, which in 50 years 

 has hardly grown 25 feet. The larch, on the contrary, shows ex- 

 cellent growth, fine form and large production, with trees of 70 cu- 

 bic feet in the bole it forms the main stand, with pine, birch, ash, 

 oak, elm, and maple as subordinate mixture in formal rows. 



It is clear that the soil had lost more than gained by the agricul- 

 tural use: the cultivation supposedly beneficial is offset by loss of 

 humus and mineral constituents, and by the removal of stones. Prob- 

 ably at first the plantations were benefited, but the benefit did not 

 last, the absence of the humus cover also causing absence of the 

 angle worms and consequent loosening of the soil. An imperfectly 

 decomposed humus from the leaf fall of the plantations covers the 

 hardened mineral soil without mixing with it. 



Chemically, also, the soil is unfavorable to deciduous trees, lack- 

 ing in lime, which in addition to other factors, like frost, undue 

 shade and the undesirable physical condition of soil has produced 

 the remarkable deterioration of the beech — a warning to consider 

 more carefully the biology of the species used in forming planta- 

 tions ! 



Das Vorwaldsystem, seine Ziele und seine Erfolge. Schweiz- 

 erische Zeitschrift fiir Forstwesen. Sept. 1906, pp. 273-278. 



Very careful and very extensive investiga- 



Variations tions are recorded by Ogiewski in the Rus- 



of sian Lesnoj journal regarding the strip 



Strip System. system with fellings in series, and in 



echelons. The factor of light and its in- 

 fluence is especially investigated in regard to duration 

 and intensity. A point a in the open is fully lighted as 

 long as the source of light lasts, a point b lying be- 

 tween two stands of timber is lighted only for a portion of the 

 time, which may be expressed as a percentage of the duration of 

 light on '«. If Z) is the length of day, S the average intensity of 

 light during the same, d the duration of light on an opening or cut, * 

 its intensity, and P the product of duration and intensity, then 

 P:100:=ds:DS, or P=^|-100. D is known, d is found by observa- 

 tion on sunny days, S and s depend on direction of the sun's rays, 

 and are expressed by the sine of the angle M, with which they 



