. REPORTS OF THE SWEDISH INSTITUTE OF EXPERIMENTAL FORESTRY, 
On the Effect of our Regeneration Measures on the formation 
of Saltpetre in the Ground and its Importance in 
the Regeneration of coniferous Forests. 
3Y HENRIK HESSELMAN. 
(Swedish text, pp. 923—1076.) 
CHaP, I. Introduction. 
Scarcely any problem in the sphere of forest economy has been discussed 
so much and given rise to such different views as the question of the easiest 
and most suitable way of regenerating the forest. When we have to study 
more closely the questions connected herewith, it is of the utmost importance 
to have a more intimate knowledge than we have so far possessed concerning 
the physiology of regeneration, a matter to which too little attention has 
hitherto been devoted. In this connection we must pay attention to the 
climate, the supply of light, and the nature of the ground. 
As regards the nature of the ground, it seems to me that the physiology 
of regeneration should be viewed in the main from two standpoints, namely 
in the first place the greater or lesser suitability of the ground for the germ- 
ination of the seed, and secondly its capacity to give the plant the requisite 
nourishment during the first years of development. The suitability of the 
ground as a germination-bed and its capacity to nourish the young plant, how- 
ever, are qualities of the ground which by no means need necessarily coin- 
cide with one another. Examples of this can be seen, for. instance, in the 
pine-heaths, where in the lichenous covering one comes across extremely 
numerous plants, the majority of which never develops any farther. Another 
example is offered by many newly drained peat-bogs, where the seeds easily 
germinate in the half-damp carpet of Sphagnum, but where most of the plants 
die sooner or later. 
The investigation- which are described in the present treatise are principally 
concerned with the capacity of the ground to nourish the young tree-plants, 
and with the effect in this respect of the usual measures for the care of the 
forest. Both theoretical and practical reasons have decided me to study in 
the first place the nitrogen. And I cherish the opinion that the results ob- 
tained confirm the correctness of my choice of this point of departure. 
CHaP. II. Increased access of light can increase or produce the 
nitrification of the nitrogen in the humus. 
It is a fact generally known that a greater and more abundant supply of 
light to the soil of the forest often produces a vegetation at once more pro- 
lific and more rich in varieties than that which is met with in dense woods. 
Usually we may ascribe this change in the vegetation solely and directly to 
