THE ASPERGILLUS TERREUS GROUP 203 



to 600m to 1 mm. deep, thinning toward the margin (fig. 58 D) and com- 

 monly spreading in unevenly radiating lines, commonly producing abundant 

 amber to brown exudate ; reverse in dark yellow shades through greenish to 

 brownish-black; odor slight. Conidiophores smooth with Avails colorless, 

 sinuate, more or less septate, slender, 4 to 6m in diameter, enlarging to a 

 hemispherical vesicle 8 to 15m in diameter or sometimes larger at the apex, 

 commonly 300 to 600m in length, occasionally up to 1000m long, and on other 

 substrata sometimes longer. Conidial heads showing chains of conidia in 

 comparatively loose columns, most frequently 20 to 30m in diameter but in 

 large heads up to 60m, with the general appearance of a snow white A. 

 terreus. Vesicular area hemispherical (fig. 57 D). Sterigmata in two series, 

 primary sterigmata 5 to 8m by 2.5 to 3.0m, secondary sterigmata 5 to 7m by 

 2 to 2.5m- Conidia 2.0 to 2.5m, rarely more, smooth, thin-walled, colorless. 



Represented in the NRRL collection by Nos. 515 (Thorn No. 5402.1), 

 288, and 1955. Repeatedly isolated from soil but less common than 

 Aspergillus carneus and the ubiquitous A. terreus. 



Typically the conidial apparatus is that of a white, loosety columnar 

 form of A. terreus. As described by Blochwitz, it does not show yellow in 

 culture. This is true of strain XRRL No. 515, although in age this culture 

 reaches dull ivory to pale buff on agar slants. In other strains, such as 

 XRRL No. 1955 from Dr. Timonin in Ottawa, Canada, limited areas mav 

 become yellow from the development of massed thick-walled hyphae as in 

 A. carneus. 



Sterigmatocystis pusilla Peyronel (I germi atmospherici dei funghi con micelio. 

 Thesis. Padova. 1931, p. 21) probably represents a synonym of A. niveus Blochwitz. 

 It was described as follows: Colonies white, very thin; sterile hyphae creeping, 

 sparingly branched, falsely septate, hyaline, 1.5 to 5/x in diameter; conidiophores 

 erect, unseptate, hyaline, 60 to 80m by 2.5 to 3m, with apical vesicles hyaline, obovoid 

 or subglobose, 7 to 10m in diameter, sterigmata radiate, in two series, with primaries 

 5 to 7/x by 2 to 2.5m and secondaries 3 to 5m by 2m in groups of 2 to 3; conidia globose 

 2 to 2.5m, hyaline, smooth. Habitat: from air in northern Italy at altitude of 1,700 

 meters. From description this would appear to represent a short-stalked member of 

 A. niveus. 



In their most typical manifestation, the conidial heads of Aspergillus 

 niveus are loosely columnar; vesicles are dome-like, and fertile over the 

 upper one-half to two-thirds only. They thus stand out in sharp contrast 

 against the typically globose heads and completely fertile vesicles of A. 

 candidus. But all heads of A. candidus are not globose, and all vesicles are 

 not fertile over their entire surface. In most strains small columnar heads, 

 not particularly different from those of A. niveus, can be found (fig. 60 D). 

 Considering this character, together with (1) the snow-white heads, (2) the 

 smooth colorless conidiophores, and (3) the small smooth conidia of both 

 species, one can readily imagine that we are here dealing with two interlock- 



