198 Modern foreSx economy. 



though thus far Austria has escaped a visitation of this 

 dreaded guest, it is felt that there is uot the least reason 

 to suspect that it will be so always. 



'According to the investigations of Rostrub, in Denmark 

 (who for years, by commission from the Minister of 

 Finance, has studied profoundly the diseases of forest 

 trees in his fatherland), the course of the disease is more 

 rapid, or more slow, according as the fungus infection 

 makes itself seen only in spots on the leaves, or as it has 

 found its way into the body of the tree. In the latter 

 case the further development advances in one or other of 

 two different ways — namely, first when the mycelium 

 penetrates to the topmost shoots, after which the tree 

 always immediately and completely dies ; or, second, when 

 the mycelium finds its way only into one branch after 

 another, mostly first into the youngest, the half-developed 

 or altogether undeveloped leaves of which soon assume a 

 brown colour, and within a short time the whole tree takes 

 on a white colouring. The mycelium (with the presence 

 of which in the body of the tree earlier investigators were 

 not acquainted), is at first entirely colourless ; later, it 

 becomes brownish. It penetrates first of all the outer and 

 inner bark, but later it penetrates also the body of the tree, 

 and spreads itself at last through the entire organism. 

 After it has pressed its way into most of the leaves, it 

 produces, often even in the year of its first appearacoe, 

 what are known as Spermogonia, or reproductive organs, 

 which everywhere break forth over the surfaces of the, by 

 this time, blanched leaves. So long as the Schuette-pile 

 only records its presence in the first-mentioned way, while 

 it only comes upon single leaves, but does not seize upon 

 -the trunk and the branches of the tree, so long may the 

 black pine still continue in the fresh spring to develope 

 new leaves, and so for a longer time present the appear- 

 ance of a healthy tree. But when, by and by, the disease 

 gains the upper hand, and the mycelium once penetrates 

 into the branches, so that from a distance one can see the 

 state of the tree from the numerous brown coloured leaves, 



