(& HENRIK HESSELMAN. 
stumps or large boughs, favour the transformation of the nitrogen 
into nitric acid. For this, however, it is necessary that the timber should 
moulder in fairly large quantities; dry and slowly mouldering branches left 
behind in the clearings seem to have no effect whatever. 
In full analogy with what has been said here stands the vegetation in the 
places where timber has been rough-hewn, or the nature of the vegetation round 
small sawmills in the forest, where one finds piles of mouldering wood in 
the form of sawdust or chips. Characteristic plants are raspberry, Epilobium 
angustifolium and Galeopsis bifida, that is to say nitratophilous flora. In such 
spots they have proved to contain a great deal of nitrate (observations have 
been made at Hassela in Hälsingland, at Hoting in Angermanland, and at 
Vilhelmina in Lapland). 
CHar. VI. The effect of the preparation of the soil on 
the transformation of nitrogen. 
(Detailed description on page 1044.) 
It is a very common observation in our forests that near upturned roots, and 
in other places where to some extent the upper layers of soil have become 
intermingled, a flora is found of quite a different character than that on the 
less disturbed soil. It is extremely common to find there raspberry and £pilo- 
bium angustifolium. The younger raspberry plants always contain 
nitrate there, and the same is usually the case with Zpilobium. This 
is very well illustrated in fig. 14, which represents a fairly large wind-caused 
gap in Ansjö Crown Park in Jämtland. Round the upturned roots there is a 
distinctly rich raspberry vegetation; in July, 1915, the raspberry plants gave 
a powerful nitrate reaction; samples of soil from the same locality formed 
considerable quantities of nitrate on storing (see Table 13, No. 2). Where 
the ground has not been disturbed in this or some similar fashion, the dom- 
inating clearing plant in Ansjö Crown Park is Azra flexuosa, and nitrification 
is either altogether lacking or extremely weak. 
Similar observations can constantly be made in our forests. The same 
phenomenon is found round forest tracks, specially if they have been quite 
recently formed. The plants that appear on bared and disturbed 
soil almost always contain nitrate. 
I have shown in a previous treatise (HESSELMAN, 1917) that the flora 
usually encountered in gravel pits and in similar localities is a markedly 
nitratophilous one. The observations here mentioned also show that even a 
small disturbance of the uppermost layers of the ground suffice to set nitri- 
fication going under circumstances where it would not otherwise appear. This 
gives me occasion to render some account of the effect of the usual prepara- 
tion of the ground of the transformation of nitrogen. 
A very illustrative and interesting account of different experiments in pre- 
paring the ground, written by TH. GRINNDAL (1911), is to be found in the 
1911 volume of the periodical published by the Forest Preservation Associa- 
tion. Of these experiments in ground-preparation, that which was carried out 
with what is called a Finnish plough in the autumn of 1912 or 1913 offered 
