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disease spreads downwards into the thicker branches, 

 passes from thèse into healthy latéral branches and may 

 flnally also attack the trunk. In that case the tree 

 succumbs. Frequently, however, it happens that the 

 disease cornes to a stand-still, especially when it has 

 reached the trunk or a thicker branch, so that it remains 

 confined to a latéral branch with its twigs. 



Very frequently branches are not attacked on the whole 

 of their circumference, but a wider or narrower strip remains 

 healthy. In such cases the diseased portion is, as a rule, 

 on the lower side of the branch. Then the healthy por- 

 tion often still bears green leaves, when the diseased part 

 has already died off. 



Sometimes the disease runs a very rapid course, and 

 the discoloration which then occurs, may often spread 

 through a distance of more than a mètre in a few days. 



In a few instances we observed, that healthy trunks 

 which had been pruned on account of the witches'broom 

 disease, were attacked by the die-back disease and killed. 

 This, however, only occurred when the branches had been 

 eut off in an unfavourable rainy reason, when the cove- 

 ring of the eut surfaces could not take place sufficiently well. 



If the bark be stripped off from an attacked branch, 

 it becomes obvions that the diseased tissuc has been 

 discoloured in a peculiar way. The diseased bark, which 

 is still alive, shows a reddish-brown colour and forms a 

 transition between the dull brown bark which is already 

 dead, and the reddish yellow portion which is still heal- 

 thy. Furthermore, the fibres show up more clearly in the 

 diseased tissue than in the healthy bark; this is partly 

 due to the fibres of the healthy tissue having the same 

 light colour as the intervening medullary rays and phloem- 

 groups, whereas in the diseased tissue the last-named 

 become brown, while the fibres préserve their original 



