ASYMMETRICA-VELUTINA 407 



P. stoloniferum and included in it numerous additional species with similar 

 conidial structures more recently described by Biourge (1923) and Zalcski 

 (1927). 



Our current study of this series has centered upon the comparative cul- 

 tural and microscopical examination of a large number of strains, including 

 many type cultures either maintained in our Collection, or contributed by 

 Prof. Westerdijk from the Centraalbureau in Baarn, or by Mr. George 

 Smith of the London School of Hygiene and Tropical Medicine. These 

 cultures appear to be quite variable, for in a number of cases cultures sup- 

 posedly from the same original source now show marked differences in cul- 

 tural appearance and to a lesser degree in details of microscopy. Further- 

 more, original descriptions of strains belonging to the series were often 

 drawn in almost identical terms, and types received as representative of 

 them fail to show sufficient basis for continued recognition of the species 

 based upon them. It is thus quite impossible to differentiate between all 

 of the species described and formerly assigned to this series. We believe 

 that a satisfactory separation into three species can be made. 



The species so accepted were among the first described, and in two of 

 the three cases are believed to represent those most generally recognized, 

 namely: Penicillium hrevi-compactum Dierckx, P. stoloniferum Thom, and 

 P. paxilli Bainier. 



The first of these, for which the series is named, is characterized by its 

 deep, looser-textured, and lightly wrinkled colonies; coarse, erect conidio- 

 phores with walls smooth or definitely roughened; and compact, often com- 

 plexly branched, penicilli with cellular elements (particularly branches and 

 metulae) commonly swollen or inflated. 



The second species is characterized particularly by its restricted growth, 

 close-texture, and strongly wrinkled colonies; comparatively thin, some- 

 what sinuous, smooth- walled conidiophores; and compressed and often 

 complexly branched penicilli without marked inflation of cellular elements. 



The third species is characterized by loose-textured, almost lanose col- 

 onies that are seldom strongly wrinkled, and more particularly by conidial 

 structures usually consisting of a simple and often large terminal verticil 

 of metulae bearing crowded sterigmata and divergent chains of conidia. 

 Viewed under high magnification, penicilli may be strongly suggestive of 

 Penicillium citrinum and allied forms except for their compactness, some- 

 what larger size, and slightly roughened conidiophores; viewed under low 

 magnifications, they show masses of tangled or divergent chains of conidia 

 rather than well marked columns. 



Penicillium hrevi-compactimi Dierclcx, in Soc. Scien. Brux, 25: 88. 1901; 

 Biourge, Monogr., La Cellule 33: fasc. 1, pp. 155-157; Col. PI. II and 

 PI. Ill, fig. 16. 1923; Thom, The Penicillia, pp. 295-296. 1930 



