422 A MANUAL OF THE PENICILLIA 



of the two species noted above, and the synonymy for the series is con- 

 sidered in connection with our discussions of these species. 



The true relationship of Penicillium cajnemherti and P. caseicolum 

 is not known. Culturally they are strikingly similar except for conidial 

 color, and commerciall}^ they are used for the manufacture of essentially 

 similar cheeses, although the former is more actively proteolytic and pro- 

 duces a somewhat softer product (fig. 111). There is a possibility that 

 P. caseicolum represents a naturally produced colorless mutant of P. 

 camemherti since such are laiown to have developed in other species, in- 

 cluding P. urticae, P. ciirinum, and P. chrysogenum. No proof of such 

 origin, however, is available and there are sufficient cultural and physio- 

 logical differences between the two to separate them easily — hence both 

 are recognized. 



Penicillium caseicolum Bainier, in Bui. Soc. Mycol. France 23: 94, PI. X, 

 figs. 6-10. 1907. Thom, The Penicillia, pp. 310-312, fig. 44A. 



1930. 

 Synonyms: P. camemherti var. rogeri Thom, in U. S, Dept. Agr., Bur. 

 Anim. Ind., Bui. 118: 52-53, fig. 17, 1910. 

 P. epsteinii Lindau, in Deutsch. Krypt. Flora, Pilze 8: 



166. 1904-1907. 

 P. rogeri Wehmer, in Lafar Tech. Mycol. 2 aufl. 4: 226. 

 1906. 



Colonies on Czapek's solution agar growing rather restrictedly, 2.0 

 to 2.5 cm. in diameter in 2 weeks at room temperature, deeply floccose, 

 cottony, azonate (fig. IIOA), central areas 2 to 3 mm. deep, white, slightly 

 furrowed, often in quadrants, conidial heads abundant, white, borne upon 

 long conidiophores arising from aerial hyphae or direct from the substra- 

 tum; limited exudate produced as small droplets, often embedded in the 

 mycelial mass, colorless; odor more or less definite, suggestive of potato 

 peels; reverse colorless or nearly so; conidial structures inconspicuous 

 from lack of color, abundantly produced over the entire colony area, par- 

 ticularly abundant along inter-colony margins, usually large, asymmetric 

 but variable in form and dimensions, bearing conidial chains more or less 

 divergent or tangled, seldom parallel and never tending to form coliunns 

 (fig. 109A); conidiophores variable in length, commonly up to 400 to 450/* 

 when arising from the substratum or 50 to lOO^i when borne as branches 

 from aerial hyphae, generally 3.0 to 4.0m in diameter, commonly roughened 

 (fig. 109B); penicilli ranging from 60 to 85m in length, as3^nmetric, branch- 

 ing irregularl}' at 2 or 3 levels below the metulae and sterigmata (fig. 

 109A), bearing conidial chains up to 50 to 75m in length; branches variable 

 in dimensions but commonly ranging from 15 to 25 or 30m by 3.0 to 4.0m, 



