IOO TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



of considerable importance in Sweden. So far as we have seen 

 this species is of no forest importance in Britain. Damage by 

 frost and canker has usually proved fatal to it. The Japanese 

 larch is also given considerable attention. In Sweden it would 

 appear to grow well but to be very productive of crooked 

 stems. This is a defect which we find in many of our British 

 plantations. 



Hendrik Hesselman produces a long report " On the effect of 

 our Regeneration measures on the formation of saltpetre in the 

 ground, and its importance in the regeneration of Coniferous 

 Forests" (English text). Reading from the English abstract 

 this study would appear to have been mainly an investigation 

 of the growth of the so-called nitratophilous plants. The 

 question of nitrification is very important in regeneration 

 measures, whether these are natural or artificial. The author 

 states that even in the best coniferous forests little or no 

 nitrification or nitrate formation occurs ; the transformation 

 does not appear to go further than the ammonia stage. 

 Thinnings or fellings allowing a great access of light are said 

 to make a radical change in the bacterial flora, and nitrification 

 becomes more active. An exception is made where the covering 

 is raw humus. In this case " there appears only a more active 

 transformation of the humus nitrogen, but no nitrification takes 

 place." The estimation of the nitrification can be done by 

 means of nitratophilous plants. The presence of nitrate is said 

 to induce the growth of raspberry, Epilobhim angusti/olwm, 

 Arenaria trinervis, Galeopsis bifida, etc. When this is lacking 

 Aim flexuosa occurs. Working the ground so that mineral soil 

 is mixed through the humus, rotting of trunks and brushwood, 

 and burning are said to produce the formation of nitrate even 

 in a markedly raw humus. 



This paper is well worthy of perusal, but in reading it one 

 must bear in mind the numerous changes which interference 

 with the growing crop introduces. There is, for instance, not 

 only an increased amount of light admitted, but, among other 

 things, the air has freer play and the competition for water is 

 lessened. (Fricke's experiments.) Under natural conditions 

 the whole question is complicated by the many factors that 

 come into play. 



In addition to the foregoing, there are reports by Nils Sylven 

 on " Melampsora (Caeoma) pinitorqua" and by Ivar Tragarth on 



