PERIODICAL LITERATURE 1053 



which had been overcut, overgrazed, and maltreated in every way. It 

 was 50 years ago when a change in management took place, and in the 

 last 25 years it is shown how the stock has been increased, the age-class 

 distribution improved, the average tree volume and the increment in- 

 creased; all this while the cut had been increased from 64 cubic feet 

 per acre in 1892 to loi cubic feet in 1916. 



The most important motion, however, was based on the fact that the 

 federal government in February, 19 17, found it necessary, in order to 

 prevent mismanagement during the war, to place all private forests 

 under the protection forest laws of 1876 and 1902, and the Society 

 proposes to press a memorial to the federal government to continue this 

 supervision of private property after the war and to revise the law of 

 1902, so as to extend the definition of protection forest in the economic 

 direction. 



A broad educational campaign among the people is to be carried on. 



Journal Forestier Suisse, September-October, 1917, pp. 153-174; 181-192. 



Wretlind^ has made an exhaustive investiga- 

 Thickness tion of the thickness of bark in Norway spruce 



of (Picca cxcelsa) and Scotch pine (Pinus sylves- 



Bark fris) in Sweden. Among the conclusions are the 



following: (i) The thickness of the bark in pine 

 at breast height maintains a constant relationship to the diameter of the 

 stem, regardless of age. In spruce, however, the proportion of bark 

 falls off in the higher diameters. (2) Spruce bark in particular shrinks 

 materially on drying. Investigations showed that the bark of a 40- 

 year-old spruce 22.7 cm. d. b. h., dried at room temperature, shrank in 

 48 hours from 4.4 mm. to 2.y mm. in thickness. The breast-high diam- 

 eter of the tree outside bark decreased during the same period from 

 22.70 cm. to 22.55 cm. This fact, aside from its commercial signifi- 

 cance, demands special consideration in investigations. (3) In spruce 

 the bark is, as a rule, thicker at the base than at breast height; it de- 

 creases slightly up to 20 to 30 per cent of the tree height and then rises 

 as the top is approached. The variations are not great, however, and 

 they are compensating to such an extent that for practical purposes the 

 bark per cent at breast height may be applied to tlie entire stem. The 

 author recommends that timber sold on the. stump be measured inside 



^Wretlind, J. E., Skogvdrds Foreningcns Tidskrift. Hiifti, January, 1017. 

 38 pages, 6 tables and 14 figures. 



