216 Studies in Forestry [CHAP. x. 



whilst Nordlinger, on the other hand, ascribed the enhance- 

 ment in increment to the increase in the foliage, but laid 

 particular stress upon what he considered the fact, that the 

 enhancement was not so much the direct result of the increase 

 in the mass of foliage as of the stimulated assimilative activity 

 of the leaves and needles, with simultaneous temporary increase 

 in the productive capacity of the soil. 



The correct explanation as to the enhanced increment is 

 probably to be found in a combination of these views. It seems 

 much more than probable that the utilization of the reserves 

 of productive matter (principally starch in various forms) is 

 most likely greatly favoured by the more active assimilation of 

 nutrients whenever the increase in the foliage takes place; 

 and there is no reason why this should not be directly con- 

 nected with the formation of the fuller crown of foliage 

 immediately after the partial clearance has been made. It is 

 still an open question how such reserves of nutrients are 

 formed, how they circulate throughout the tree, and how they 

 are finally utilized, although their existence in the parenchym- 

 cells of woody-fibrous plants is just as well known as that of 

 similar reserves in orchids, perennial tuberous plants, &c. The 

 recent destruction of forests in Bavaria by the Nun moth has 

 given Professor R. Hartig of Munich special opportunities for 

 studying a part of this subject, particularly with regard to the 

 Spruce l ; and he has conclusively proved that this species of 

 tree has much fewer reserve supplies of nutrients than the Scots 

 Pine. In general, as is well known, such reserve supplies are 

 far more plentiful in the broad-leaved deciduous species of 

 trees than in conifers, and larger in the deciduous Larch than 

 in the evergreen conifers. All the changes that take place in 

 trees prior to the commencement of the assimilative activity in 

 spring are ascribable to these nutrient reserves the flowering 



1 See Forstlich-naturwissenschaftliche Zeitschrift for January, February, 

 and March 1892. 



