THE ASPERGILLUS GLAUCUS GROUP 107 



occasionally up to 125/x; asci 10 to 12ju; ascospores lenticular, mostly 4.8 

 to 5.6/x by 3.8 to 4.4ju, smooth-walled, with equatorial area rounded or 

 somewhat flattened and occasionally indented showing a trace of furrow 

 but without crests or ridges (fig. 27 A). Conidial heads abundant, varying 

 in different strains from 125 to 175m in diameter, consisting of diverging 

 chains of conidia radiating from a hemispherical vesicular apex of the 

 conidiophore (fig. 28 A); conidiophores smooth, mostly colorless, 500 to 

 1,000/x in length, broadening at the apex to a vesicular area, about 25 to 

 40/i m diameter; sterigmata in one series 7 to 10/z by 3.5 to 4.5/u; conidia 

 elliptical to subglobose, spinulose, mostly 5 to 6.5/x. 



Represented by cultures NRRL No. 12, No. 17, and more than a score 

 of others included in this study. In this connection it should be noted 

 that of 37 cultures examined in the present study that produced ascospores 

 characteristic of the A . repens series, 29 produced colonies and microscopic 

 details that place them in the species A. repens as described. 



This description is manifestly broad enough to include strains approxi- 

 mating the description given by Bainier and Sartory for Aspergillus scheelei 

 and Aspergillus B var. scheelei (1912b). Evidently A . scheelei was thought 

 by the describers to represent a species with somewhat larger ascospores 

 showing a more definite furrow, whereas Aspergillus B var. scheelei was a 

 strain with smaller ascospores almost without a trace of furrow. Both 

 species were described as characterized by the production of a yellow pig- 

 ment. In the authors' experience, a distinction based upon color is largely 

 invalidated by variants bridging the whole range from yellow-orange to 

 deep orange-red and even shades of brown when large numbers of strains 

 of this series are compared in culture. Strains also vary slightly in the 

 pattern of their ascospores, some rarely producing spores with a trace of 

 furrow and others bearing a large proportion with such traces. But among 

 spores of a single strain limited variation in this character is normally 

 encountered. Thus the presence or absence of a slight furrow, unless 

 accompanied by significant differences in morphology or colony character, 

 would not seem to justify specific descriptions in this series. 



A strain designated as Aspergillus dierckxii, presumably by Biourge 

 but thus far unpublished, was included in Gould and Raistrick's study of 

 pigment production in the A. glaucus group (1934). As received from 

 Raistrick's laboratory, this organism (NRRL No. 39) produces colonies 

 showing no zonate arrangement of conidial heads. Further, heads are 

 borne on shorter conidiophores than in typical A. repens and consist of 

 columns of conidia rather than radiating chains. Little or no red color 

 appears in the colonies or in reverse. Although no other strains showing 

 exactly these differences have appeared in the authors' collection, separa- 

 tion as a distinct species is believed unwarranted. 



