100 Transactions British Mycological Society. 



ON DEMATIUM PULLULANS DE BARY. 



By Isfue A. Hoggan, Bathurst Student of Newnham 

 College, Cambridge. 



In the course of certain cultural work on fungi, the writer 

 has frequently encountered the form Dematium pullulans de 

 Bar3^ In view of the uncertainty prevalent in recent myco- 

 logical literature as to the identity of this fungus, the following 

 note was written on the suggestion of Mr F. T. Brooks. 



I. Morphological Characters of the Fungus. 



The name Dematium pullulans was given by de Bary(i) to 

 a fungus commonly occurring on the surface of plants and 

 characterised by small ellipsoid conidia which were abstricted 

 in large numbers in water or in sugar solutions from colourless, 

 branched, septate hyphae, and which budded in the liquid after 

 the manner of yeast cells. When the food supply was exhausted, 

 both hyphae and bud-spores passed into a resting stage; the 

 individual cells became rounded, with thick, dark-coloured 

 membranes, and one or more oil-drops developed. On trans- 

 ference to fresh medium, the resting cells germinated after a 

 short period, each cell sending out a single germ-tube which 

 gave rise to hyaline hyphae abstricting fresh conidia. 



The following year Loew(2) published a fuller account of the 

 same fungus, including details of the origin and development 

 of the conidia and the formation of resting cells, or "gemmae," 

 in a medium such as grape- juice. The yeast-like budding of 

 the conidia ceased with failure of the food-supply. In certain 

 of the spores a constriction appeared in the centre, and a 

 transverse septum arose dividing the spore into two cells. 

 Frequently other cross-walls followed, giving rise to a chain of 

 from three to six cells. Other spores increased greatly in size 

 but remained aseptate. The protoplasm became vacuolate 

 and frequently developed a characteristic oil-globule at either 

 pole. While these changes were taking place, the cell-wall 

 gradually thickened and darkened, assuming first a golden, 

 then olive-green or brown hue ; numerous drops of oil appeared 

 in the protoplasm. The final stage was reached after about five 

 or six days' culture in grape- juice. 



The individual cells of the hyphae underwent similar changes. 

 On transference to fresh medium both these and the gemmae 

 proper sent out hyaline hyphae which rapidly proceeded to 

 abstriction of conidia after the characteristic Dematium manner. 



