ASYMMETRICA-VELUTINA 395 



anticipated among strains in cosmopolitan and variable species such as 

 P. roquejorti, hence, in our opinion, do not warrant continued recognition. 

 Identification of newly isolated cultures with one of the species descriptions 

 published by Sopp, Weidemann, Bainier, or Biourge is scarcely probable. 

 However, these descriptions may be illuminating as emphasizing the range 

 of variations found within the series, since in a general way they characterize 

 more or less definite members of a variable series of related organisms. 



The series embraces only one well-defined species in addition to Penicil- 

 lium roquejorti Thom, namely: P. casei Staub. This latter species is rather 

 frequently encountered as an infection of the rind of Swiss and related 

 cheeses where it produces small areas of brownish discoloration. In agar 

 plate cultures it shows the general characteristics of the series in the pattern 

 and markings of conidial structiu'es but consistently produces more re- 

 stricted colonies with less arachnoid margins than strains of P. roquejorti 

 Thom. 



Penicillium roquejorti Thom, in U. S. Dept. Agr., Bur. Anim. Ind., Bui. 82, 



pp. 35-36, fig. 2. 1906. Also t6frf., 118, p. 34, fig. 4. 1910; and 



The Penicillia, pp. 277-279, fig. 38. 1930 



Colonies on Czapek's solution agar (Col. PL VI) spreading broadly, at- 

 taining a diameter of 5.0 to 6.0 cm. in 10 to 12 days at room temperature, 

 heavy sporing, velvety with surface fairly smooth or plane, with margin 

 broad, white, thin (fig. lOoB), cobwebby or veil-like (arachnoid) with hy- 

 phae radiating partly on the surface and partly just below the surface of 

 the substratum, and green conidial areas following the hyphae in unevenl}^ 

 radiating lines (constituting the basis of Biourge's section Stellata), forming 

 a mass 100 to 300iu deep, at margin white then bluish green near gnaphalium 

 green or pea green (Ridgway, PI. XLVII) and then quickly dull green near 

 Russian green (R., PI. XLII); no exudate produced in most strains; odor 

 not characteristic or pronounced, slightly sour or moldy; reverse in shades 

 of green or bluish green to almost black, varying with conditions of culture 

 and often in different sectors in the same colony; penicilli variable in pat- 

 tern from simple monoverticillate structures (fig. IO4B3), to verticils of 

 metulae and sterigmata, or compact branching systems, with one or more 

 long appressed or diverging branches (fig. 104Bi and 2), sometimes giving a 

 cymose appearance, bearing conidia in long tangled chains or forming loose 

 columns (fig. 104A); conidiophores mostly short, usually about 100 to 150iu, 

 less frequently up to 200m long by 4.0 to 6.0m in diameter, ascending from 

 aerial loops or submerged sections of vegetative hyphae, often branched, 

 with walls granular from encrustments or protuberances of variable size 

 (occasionally smooth) (fig. 104B); metulae 12 to 15/i by 3.0 to 4.5/i, mostly 

 with walls more or less roughened or asperulate (fig. 104B) ; sterigmata 8.0 



