642 A MANUAL OF THE PENICILLIA 



of its conidia. Despite the fact that the species does not conform very 

 closely with other members of the P. purpurogenum series, it is our belief 

 that mycologists and microbiologists encountering this species in culture 

 will locate it here more conveniently than elsewhere. 



Penicillium variahile Sopp, in Monogr., pp. 169-171; Taf. XVIII, fig. 124; 



Taf. XXIII, fig. 27. 1912. Thom, The Penicillia, 



pp. 477-478. 1930. 



Colonies on Czapek's solution agar attaining a diameter of 2.5 to 3.0 cm. 

 in 12 to 14 days, usually radially furrowed (fig. 163D), consisting of a fairly 

 tough mycelial felt 200/x or more deep, appearing velvety or slightly granu- 

 lar, usually developing abundant conidial structures which may be con- 

 centrated in central colony areas, arranged in conspicuous zones, or ir- 

 regularly produced in localized areas or patches, growing margin usually 

 conspicuous, in white through cream to bright yellow shades, commonly 

 1 to 2 mm. wide; colonies variously colored, with heavily sporing areas 

 ranging from sage green to slate olive or andover green (Ridgway, PL 

 XLVII) and with lighter sporing areas near Hathi gray to storm gray (R., 

 PI. LII), commonly showing extensive non-sporulating areas (fig. 163D) 

 variously colored in bright yellow, cream yellow, to orange buff shades 

 depending upon the age and abundance of yellow encrusted sterile hyphae, 

 sporulating and non-sporulating areas often intermixed to present a mottled 

 appearance; exudate lacking or limited in amount, usually clear; odor not 

 pronounced; reverse in yellow to orange-brown shades, often showing a 

 greenish cast, less commonly orange-red; conidiophores arising from the 

 mycelial felt, or in marginal areas of older colonies directly from the sub- 

 stratum, often short but sometimes up to 200/x or more in length by 2.5 to 

 3.0/x, smooth- walled, sometimes branched; penicilli typically biverticil- 

 lately symmetrical, usually consisting of a single verticil of 5 to 7 metulae, 

 varying in length from 7.5 to lO/x in some strains to 12 to 14ju in others; 

 sterigmata typically lanceolate, tapered, in clusters of 5 to 7, measuring 

 10 to 12m by 1.8 to 2.2^ conidia strongly elliptical, with ends often more or 

 less pointed, mostly 3.0 to 3.5 by 2.0 to 2.5)li, but showing great variability 

 in size, occasionally up to 7 to 8/i in long axis, with walls smooth or appear- 

 ing irregularly roughened in very large conidia. 



Colonies on steep agar 3 to 3.5 cm. in 2 weeks, plane or lightly furrowed, 

 heavily sporing throughout, in dull yellow-green to gray -green shades, show- 

 ing little or no admixture of sterile yellow hyphae in some strains, abundant 

 in others; exudate lacking; odor indistinct; reverse in yellow-orange to dull 

 brown shades, commonly more or less mottled; conidial structures as de- 

 scribed above. 



Colonies on malt agar (fig. 163E) essentially as on steep but with mar- 



