On Dematium pullulans de Bary. Isme A. Hoggan. 105 



and in morphological characters to the Dematium pullulans of 

 Loew and Laurent as to leave no doubt in the mind of the writer 

 that she was dealing \\-ith the same fungus. Shght variations 

 in beha\'iour were noted at times among the different strains, 

 but these were not considered sufficiently marked to necessitate 

 any separation into species as Berlese suggested. On the other 

 hand several striking differences, both macroscopic and micro- 

 scopic, have been observed between the Dematium cultures and 

 those of Plowrightia ; so that, although the work is still in pro- 

 gress, it is hoped that a prehminary account of the cultures of 

 Plowrightia ^\•lll not be out of place. 



(i) Cultures on currant uvod blocks. The difference in macro- 

 scopic appearance of the two forms was here verv striking. 

 Dematium spores budded in great profusion on the wood, forming 

 a white, slimy mass, which later became almost entirely black 

 as gemma-formation proceeded, ^'erv little or no mvcehum 

 developed; this, if present, remained sparse and white. 



Plonrightia spores, on the other hand, immediately gave rise 

 to an abundant mycehum extending over the whole surface of 

 the wood, becoming rapidlv gre\*ish green or bro\\"n in colour 

 and long and fluffy in texture. Xo trace of budding spores was 

 found. Later, black, club-shaped organs, one to several milH- 

 metres long, appeared, possibly perithecial in nature. Nothing 

 corresponding to this was observed in the Dematium cultures. 



(ii) Cultures on Dox's agar. Dematium spores budded for 

 several days forming a white, waxy mass almost bacterial in 

 appearance. Later, h\-phae developed on the surface of the 

 slant, bearing masses of conidia. The cultures remained white 

 for several months, or occasionally a shght blackening of the 

 h^-phae was observed. 



Plonrightia spores behaved similarly at first, but the developing 

 h\-phae bore fewer or no conidia. The waxy masses rapidly 

 coloured to a dirty yellow or black, so that the cultures could 

 readily be distinguished from those of the former fungus. 



(iii) Cultures on currant wood-extract agar. Dematium spores 

 budded for several days, after which a superficial mycehum 

 developed bearing masses of conidia. 



Plourightia spores behaved similarly. After about a fortnight 

 the hyphae and spores had become very dark in colour, con- 

 trasting with the still colourless growths of Dematium. 



Cultures were also made from portions of mycelium placed 

 at the top of the agar slant. The subsequent growth in the case 

 of Dematium was confined to the surface of the medium or 

 deeper layers, and consisted of h\'phae bearing numerous 

 conidia. In time the mycehum darkened somewhat. 



Plowrightia ga\-e rise in addition to a dense, greenish, aerial 



