io6 Transactions British Mycological Society. 



mycelium on the upper half of the slant, which had no counter- 

 part in the Dematium tubes. The superficial mycelium darkened 

 much more rapidly; after a few days the formation of conidia 

 on the hyphae ceased, and in old cultures the greater part of 

 the mycelium was found to be completely sterile. 



(iv) Cultures on beerwort agar. These cultures also presented 

 strikingly different appearances to the naked eye. Old Dematium 

 cultures showed a black, leathery layer covering the surface 

 of the agar, and consisting of dark-coloured hyphae and numerous 

 gemmae. Scattered over this black layer were white, slimy 

 masses of bud spores, and isolated patches of a short, downy, 

 white mycelium. 



The Plowrightia cultures also showed a black surface layer, 

 but this consisted entirely of dark-coloured hyphae, no gemmae 

 being observed in any part. In addition, the layer was covered 

 by a dense, greenish, fluffy mycelium, amongst which numerous 

 greenish or black, spherical or club-shaped pustules had de- 

 veloped. Other similar black pustules had arisen on the under 

 surface of the shrunken agar. 



(v) Hanging drop cultures, [a) Currant wood-extract agar. On 

 agar drops Dematium spores budded in great profusion forming 

 dense masses of bud cells, which spread with great rapidity over 

 the surface of the agar. No trace of mycelium was observed 

 until, after several days, the drop began to dry up, when a few 

 fine poorly-developed hyphae appeared on the edge of the agar. 



Plowrightia spores gave rise immediately to an abundant 

 mycelium which soon abstricted numerous conidia. 



[h] Beerwort drops. Dematium spores gave rise to a profuse, 

 stout, hyaline mycelium abstricting masses of conidia which 

 budded in the liquid. Gemma formation proceeded on the edge of 

 the drop, apparently where this was beginning to dry up. In the 

 centre of the liquid the fungus remained hyaline for a week or more. 



Plowrightia spores gave rise similarly to mycelium and conidia, 

 but these darkened rapidly throughout the liquid, and in two or 

 three days the transformation into gemmae and resting mycelium 

 was complete throughout. 



From these observations it appears that Dematium pullulans 

 and the conidial stage of Plowrightia ribesia are not identical. 

 The differences shown between the two forms in culture are 

 considered sufficiently striking to warrant the retention of the 

 specific name for the former fungus, and recognition of it as 

 a distinct entity. 



With regard to Sphaerulina inter mixta, the writer has not 

 yet succeeded in obtaining material with which to carry out 

 a similar investigation; hence the possibility of the identity of 

 Dematium pullulans with this fungus is not excluded. 



