W. N. C. Bblgrave 



187 



Effects of the fungi on the tissues of the host. 



The action of the fungi on the tissue of the host has been examined. 

 The stains found most effective in this examination were Delafield's 

 Haematoxylin, and the double stain Picric-Aniline Blue (picric acid 

 being added to saturation). 



It is found that the hyphae travel in the soft tissues of the bark, 

 thence spreading laterally into the wood (cf. Fig. 5). 



Fig. 5. 



In all the tissues gum makes its appearance, in the bark and medul- 

 lary rays as droplets ; in the wood large masses are of frequent occurrence. 

 As pointed out above, the diseased areas are easily identified by their 

 collapsed bark. This collapse is caused by the death and decay of all 

 living cells, only the fibrous cells remaining. It is usual to find above 

 the junction areas of collapsed and healthy areas of bark, considerable 

 lengths of red or brown wood, in which no hyphae can be traced, but 

 gum is abundant (cf. Fig. 6). This phenomenon, however caused, is 

 of common occurrence. 



