348 A MANUAL OF THE PENICILLIA 



upon Czapek's solution agar 3.0 to 4.0 cm. in diameter at 10 days, typically 

 velvety, often plane but sometimes showing broad radial furrows, lily green 

 to slate olive in color (R., PL XLVII), producing limited pale yellow exu- 

 date, and showing colony reverse in dull to fairly bright yellow shades. 

 Colonies upon malt extract agar indistinguishable from those of typical 

 strains. Penicilli are entirely typical. Citrinin is produced. Representa- 

 tive of such forms is culture NRRL 1171, isolated from waste sulfite liquor, 

 and numerous strains, such as NRRL 2143, isolated from deteriorating 

 military equipment in tropical and sub-tropical areas. 



(2) Floccose, lightly sporulating strains: Colonies upon Czapek and 

 steep agars typically floccose, loose-textured, up to 2 mm. deep (fig. 92E), 

 penicilli often late in appearing and borne almost exclusively from aerial 

 hyphae, exudate limited, colorless to pale yellow; reverse uncolored to very 

 pale yellow. Colonies upon malt agar are restricted and typical of the 

 species (fig. 92F). Penicilli approximate those of typical strains of Peni- 

 cillium citrinum in form and dimensions of parts. Some citrinin is pro- 

 duced. Represented by NRRL 1841 received in 1942 from George Smith, 

 London School of Hygiene and Tropical Medicine, as "P. citrinum Thom 

 No. P6"; and NRRL 2144, isolated by Dr. Richard Baines, California 

 Department of Agriculture, Sacramento, California, from a nylon para- 

 chute returned from the South Pacific area. 



(3) Forms transitional toward the Penicillium chrysogenum series: 

 Colonies upon Czapek's solution agar 3.0 to 4.0 cm. in diameter at 10 days, 

 loose-textured, 1 to 2 mm. deep somewhat floccose, plane or radially fur- 

 rowed, medium to heavy sporing, court gray to artemisia green (R., PL 

 XLVII), exudate pale .yellow, and reverse in pale yellow shades. Colonies 

 on malt agar growing more rapidly than on Czapek. Conidiophores are 

 consistently longer than in typical P. citrinum strains but penicilli are 

 essentially typical of the species. These forms seem to represent a transi- 

 tional step between P. citrinum Thom and P. notatum Westling. Assign- 

 ment to an intermediate position is substantiated by an apparent capacity 

 to produce both citrinin and penicillin, when tested in spectrum plate cul- 

 tures against selected bacterial species (L. J. Wickerham, unpublished 

 notes). Representative of these forms is NRRL 822 (Thom No. 4482), 

 received in 1921 from Dr. Frank Forrey from the sputum of a woman with 

 a lung disease. 



(4) Forms transitional toward the Monoverticillata : Colonies essentially 

 duplicating typical strains of Penicillium citrinum in rate of growth, pat- 

 tern, texture, spore production and color of conidial surface and reverse; 

 but with conidial structures usually somewhat more variable, and often 

 appearing ramigenous. Conidiophores partly long trailing hyphae, partly 

 short branches from aerial hyphae, and partly erect structures of inter- 



