332 A MANUAL or THE PENICILLIA 



same colors as the exudate and coloring the surrounding agar, in others at 

 first grayish lavender, becoming purplish brown in age; penicilli variable, 

 commonly monoverticillate but frequently consisting of a terminal group 

 of diverging and unequal branches or metulae, irregularly arranged, de- 

 veloped either at the tip of the main axis or arising from lower nodes; 

 conidiophores with walls granular-tuberculate (fig. 89D), usually less than 

 lOOyu long by 2.0 to 3.0/x; metulae usually 10 to 20/x by 2.0 to 2.5^ with walls 

 granular; sterigmata in clusters of 5 to 10, compactly arranged, mostly 

 6 to 8^ by 2.0 to 2.5/x, broadest in central area with apices abruptly nar- 

 rowed and tending to diverge, bearing conidia in chains up to 100m in 

 length, commonly divergent; conidia globose, about 3.0 to 3.5/i in diameter 

 with walls conspicuously echinulate (fig. 89D). 



Colonies on steep agar growing more rapidly, approximately 4.5 to 5.0 

 cm. in diameter in 12 to 14 days, velvety, strongly furrowed in a radial 

 pattern, heavily sporing throughout (fig. 89C), with growing margin 0.5 

 to 1.0 mm. wide, white, quickly shading to deep grajash olive and to hair 

 brown in age (R. PI. XLVI); odor suggesting mushrooms; no exudate; 

 reverse through dull lavender-gray shades to dull reddish brown; penicilli 

 as described above. 



Colonies on malt agar attaining a diameter of 3.0 to 4.0 cm. in two weeks, 

 plane, velvety, heavily sporing (fig. 89B), quickly becoming deep grayish 

 olive; conidial structures as described above but with stalks more coarsely 

 roughened. 



Species description centered upon XRRL 2041, received from the Cen- 

 traalbureau in April 1946, as a strain contributed by Thom in 1930. This 

 culture probably represents the type strain sent to Baarn at the time of the 

 publication of Thom's Monograph. It differs from the original descrip- 

 tion, and from that presented above, only in the absence of exudate. 

 NRRL 848, of unknown origin, on the other hand, produces colonies with 

 exudate in strict agreement with the original description. The species is 

 often encountered in soil dilution plates. The type strain was isolated by 

 Dr. Elias Melin from forest soil. 



PeniciUium melinii is assigned to the Divaricata since an appreciable 

 number of the conidial structures show the divaricate character typical of 

 this group (fig. 89D). Many, if not an actual majority, of the penicilli, 

 however, appear monoverticillate and a possible relationship to this group 

 must be recognized. The globose, strongly echinulate conidia are strik- 

 ingly similar to P. nigricans, as is also the general character of its branched 

 penicilli. Color production likewise runs to orange-browns in both 

 species. It differs from P. nigricans particularly in producing conidio- 

 phores that are conspicuously granulate whereas the conidiophores in 

 P. nigricans are smooth-walled. 



