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him in Malaya, though it appears a constant feature. It is very transitory 

 as observed in the Laboratory; 4-5 days is the actual time between its 

 appearance and the dispersal of the spores, (b) is the upper black zone, 

 composed of compact tissue very similar to that composing the black lines, 

 as seen in a diseased collar, (c) is a white loosely compacted zone in 

 which the globular perithecia are formed, (d) is a broader band, grey 

 in colour and leathery in consistency, (e) is the black zone on the under 

 surface, which is continuous at the margins with the black zone towards 

 the upper surface. 



The globose perithecia communicate with the exterior by very narrow 

 channels. The first formed elements of the perithecia can be recognised 

 in suitably stained sections very early in the development of the fructifi- 

 cation, long before the production of conidia. These elements stain more 

 deeply with protoplasmic stains than surrounding ones and appear as 

 small circular patches of spirally running hyphae. 



In the early stages of development, the black zone is not present in 

 the fructification. Whilst the stroma is still soft and yellowish, the walls 

 of patches of cells of the loosely compacted layer, irregularly distributed, 

 but at the same depth, become impregnated with carbonaceous material. 

 Later, the walls of the cells of the loosely compacted layer intervening 

 between the black patches become impregnated with similar material, 

 their cell contents darken, and a continuous black, brittle zone is formed. 

 It is a very characteristic zone, and can be used as a rough diagnostic 

 feature when studying the variable forms of fructifications produced by 

 this fungus. This zone is always present in the " Xylaria " forms of the 

 fungus ; many true Xylarias are found on rubber trees killed by JJ. zonata, 

 but these do not show the black carbonaceous zone to which the fructifi- 

 cation of TJ. zonata owes its brittleness. The greenish-grey conidial layer 

 is formed about the time the black zone is completed, while the fructifi- 

 cation is still rather soft and leathery. In many cases observed, the 

 conidial layer is restricted to the younger, growing edges of the fructifi- 

 cation, while the older parts in the middle are showing the ostioles of the 

 perithecia. The hyaline conidia are abstricted abundantly from the 



