Miss Dale, Notes on Artificial Cultures of Xylaria. 101 



which have produced conidia ultimately shrink and become over- 

 run by the flocculent parts of the mycelium. The sterile stromata 

 are still growing. Free conidiophores were also produced in 

 X. polymorpha, while in X. Hypoxylon conidia were developed on 

 small tufts of hyphae united into coremium-like bodies. Up to 

 the present, only the conidia from the free conidiophores of 

 X. polymorpha have germinated 1 . They give rise to a thin 

 mycelium which slowly spreads over the substratum and which is 

 very unlike the dense flocculent masses so rapidly formed from 

 ascospores, although the young mycelia as seen under the micro- 

 scope are very similar in both cases. 



The structure of these conidiophores as seen in microtome 

 sections is remarkably like that of certain Basidiomycetes. The 

 centre of the organ consists of a dense mass of hyphae, somewhat 

 interlacing but running approximately parallel to the long axis. 

 Towards the periphery the tissue becomes looser and bends out- 

 wards, forming parallel branches which stand close together like a 

 hymenium. The branches are septate and each forms a single 

 spore on a sterigma-like process which, after the abstriction of the 

 spore, remains as a pointed prolongation of the spore-bearing 

 branch. 



The action of the fungus in destroying the wood which forms 

 its substratum shews some points of interest. Pieces of wood 

 were hardened in Flemming's solution, and transverse, radial, and 

 tangential sections were cut. The hyphae had penetrated into all 

 the tissues and could be seen running along the medullary rays 

 and down the vessels, wood-fibres, and wood parenchyma. The 

 hyphae varied considerably in thickness, the larger ones being 

 chiefly in the wide vessels. In all cases the mycelium passed 

 from cell to cell by means of the pits. One of the most striking 

 points is the way in which the wood-fibres are affected. In radial 

 sections some of the hyphae in the fibres are seen to run in a 

 straight line, while others take a spiral course and are united to 

 the straight hyphae by connecting branches. The explanation of 

 this seems to be that the hyphae make their way first into the often 

 narrow lumen of a fibre, and that from these hyphae there are 

 formed branches which penetrate the pits and grow spirally round 

 in the wall, decomposing it as they go, evidently by excreting 

 some wood-destroying enzyme. Often two or three hyphae may 

 be seen forming as many spirals round a fibre and lying in 

 channels which they have made in the cell-wall. 



1 Since the above notes were written conidia from old conidiophores of Xylaria 

 polymorpha have germinated. 



