i8o Transactions British Mycological Society. 



a re-arrangement at the base, and leaving the centre as the 

 driest region." The present writer's observations go to support 

 these conclusions. Water-soaked areas appear first of all in the 

 branch stumps in early spring and in most cases spread gradually 

 towards the circumference. Central water-soaked areas have 

 been noticed, however, in early autumn, and it is remarkable 

 that the fluxes are active practically all the year round. Prof. 

 Craib suggests that there might also be summer water-storage. 



All stages have been traced between these water-soaked areas 

 and the typical flux ; at least a year appears to be necessary for 

 the development of the latter. The clear fluid exuding from 

 the water-soaked areas is alkaline {pH about 9) and flows in 

 greatest quantity during hot weather*. Sugars are either absent 

 or occur only as traces. 



The medullary rays and wood parenchyma of the water- 

 soaked wood are full of a gummy substance, partly tannin and 

 partly starch, which gives the wood a brown colour. In the 

 later stages of the flux the vessels may be invaded by hyphae 

 and bacteria, in which case both vessels and parenchjnnatous 

 cells become filled with gum. The bark surrounding old fluxes 

 becomes blackened superficially. 



It is possible that in the case of wounds on the trunks of 

 trees, brown fluxes may develop from a simple sap-flow. Sap- 

 flows from artificial bore-holes in horse-chestnut trees quickly 

 developed some of the typical insect-larvae and fungi, but the 

 flow was not so constant as in the case of heart-wood exuda- 

 tions. 



Numerous inoculation experiments were carried out but in 

 no case did a typical flux appear within the time available. 



In order to discover if possible any noticeable effect of 

 these organisms on wood tissues and cellulose, cultures were 

 made on sterile wood blocks, twigs, sawdust, sawdust and 

 nutrient solutions, sterile filter paper, cellulose and filter paper 

 agars, etc., etc. These experiments showed that none of the 

 organisms (fungi, yeasts, and bacteria) have any marked dis- 

 integrating action on woody or cellulose tissues. This might have 

 been expected, since no decomposition of wood or bark takes 

 place except after prolonged periods. 



The white fluxes are totally confined to the bark and without 

 doubt arise in the phloem. Willow fluxes were distinctly acid 

 (^H 6 to 6-7). No sugars were detected in these, but somewhat 

 similar white fluxes of Ulmus campestris were distinctly sticky 

 and contained large quantities of glucose. Exudations of this 

 nature are not uncommon from the bark of trees which have 



* About o 750.0. was collected in half-an -hour. 



