398 A MANUAL OF THE PENICILLIA 



isolated originally from French Roquefort cheese in 1904, and numerous 

 other strains possessing similar cultiu'al and morphological characteristics 

 that have been isolated by the authors or received from collaborators over 

 a period of many years. Among such cultures now contained in our Collec- 

 tion may be mentioned NRRL 850, received in 1930 from Dr. W. T. John- 

 son, Grove City, Pennsylvania; NRRL 852 from the same source in 1933; 

 NRRL 853 from Professor F. D. Heald, State College of Washington in 

 1930; NRRL 854 from Dr. Paul Simonart, brought by him from Biourge's 

 Laboratory in 1936; NRRL 858 from Biourge as his Penicillium gorgonzola; 

 and a number of strains received in 1943 from Dr. E. R. Hiscox, National 

 Institute for Research in Dairying, North Reading, England. 



Other strains contained in this Collection fail to duplicate NRRL 849 

 and similar forms in all particulars, but do not differ from them sufficiently 

 to warrant separate recognition. These include: NRRL 851, received in 

 1940 from Dr. M. M. Harris, Waycross, Georgia; and NRRL 1168, received 

 in 1940 from Dr. G. A. Ledingham, Ottawa, Canada. Both of these pro- 

 duce colonies with denser and less arachnoid margins, are usually heavier 

 sporing, show a brighter green coloration in conidial areas ranging from 

 pistachio green to dark American green (R., PI. XLI), and run toward dark 

 brown rather than dark green or greenish black in colony reverse. A cul- 

 ture received from the Centraalbureau in May 1946 as the type of Peni- 

 cillium roqueforti var. viride Dattilo-Rubbo shows the same bright yellow- 

 green colors and general cultural characteristics of the above. Variants of 

 this type are fairly common, but lack sufficient bases for specific, or varietal 

 recognition. 



Other strains, not complying with either of the above groups, include: 

 NRRL 857, received from Biourge as Penicillium gorgonzola Weidemann; 

 NRRL 855, from Dr. Paul Simonart as Biourge's culture No. 156; and 

 NRRL 1165, isolated from waste sulfite liquor by G. A. Ledingham, Ottawa, 

 Canada. These cultures produce almost floccose, sparsely sporing colonies 

 which are light blue-green in color and show little or no color in reverse. 

 Recognition of P. gorgonzola to include cultures of this type is not warranted 

 since the strains involved show only quantitative differences in spore pro- 

 duction and development of aerial hyphae from typical P. roqueforti strains, 

 and since cultures of this particular type are not claimed to be especially 

 significant in the production of Gorgonzola cheese. 



While considerable variation characterizes the different members of the 

 Penicillium roqueforti series, it is interesting to note that, unlike cultures of 

 P. oxalicurn (p. 378), specific strains usually remain stable over long periods 

 of time in laboratory culture. Strain NRRL 849 (Thom's No. 18), for 

 example, duplicates in all essential characters the appearance and mor- 



