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upper epidermal cells separated as a layer from the palisade 

 cells; the palisade cells fell apart and were found to be filled 

 with a brownish coloured material which gave a silver-brown 

 appearence to the leaves. No hyphae were to be obtained in the 

 leaves or petiole, nor could they be traced in any of the twigs 

 which measured less than 8 in. in length, although these 



twigs showed on cutting conspicuous discoloration from the basal 

 end upwards. 



The variety " Grenadier " was only slightly attacked, and instead 

 cf a shiny grey brownish tint on the upper surface, as in * Lord 

 Grosvenor," the leaves were a dark leaden colour. There was no 

 separation or falling apart of the epidermal or palisade cells. 

 In hand sections, the leaves seemed almost normal, with the 

 exception of a reduction in chloroplasts, and there was no sign of 

 discoloration in the twigs. Although I was unable to examine 

 the trees in the field, it is presumable from the information 

 received, together with the above observations, that the apparent 

 silvering in the variety " Grenadier" cannot be attributed to the 

 action of a foreign organism ; the lead colour is probably due to 

 some physiological weakness of the tree. 



Early in January, 1919, I observed a tree, stated to be 

 " Bramley's Seedling," growing in a cottage garden at New Cross, 

 London, which produced numerous confluent masses of fructifica- 

 tions of Stereum purpureum on a side-branch towards the base 

 of the stem ; the branches developing immediately above this on 

 the same side of the tree produced also tiny scattered tufts of the 

 fungus. On cutting off the lowest branch near the stem, the 

 characteristic browning could be seen at the amputated ends, 

 and on removal of the bark the discoloration was found to extend 

 down to the roots. The discoloration extended from the super- 

 ficial roots upwards into the main stem, whence it passed into 

 the main branches and twigs, affecting about half of the crown 

 of the tree, the other half being apparently normal. In the 

 main stem a segment of the wood, occupying about one quarter 

 of the whole area in transverse section, showed marked (lis- 

 coloration which extended from the cambium to the pith. 

 Owing to the very advanced state of the disease it was difficult 

 to draw definite conclusions as to whether infection took place 

 below soil level or from injured branches. Curiously enough, 

 the diseased part of the tree had suffered severely during the 

 last few years from " American Blight " (Eriosoma lanigera) ; the 

 damage caused by these insects was very marked on the branches 

 and the twigs, as shown by the presence of intumescences and 

 abnormal growth. It is highly probable that the punctures and 

 the subsequent wounds produced by this insect facilitated the 

 penetration of S. purpureum. 



Well-developed mycelium in the twigs, branches and main 

 stem was to be observed in longitudinal sections of the discoloured 

 wood. The fine threads could be easily traced from the branches 

 into the fruiting spurs, but with greater difficulty in the one- 

 year-old twigs; the hyphae branched frequently and were of 

 irregular thickness (see Text Fig. 3). They were found more 

 abundantly in the external lavers of xvlein than in the inner: 



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