Fig. 41. Aspergillus nidulans group; different species growing upon Czapek's 

 solution agar at room temperature. A, A. nidulans NRRL No. 194, typical strain 

 producing very abundant dark green conidial heads. B, Naturally occurring muta- 

 tion characterized by white heads, isolated from the preceding strain by Edward 

 Yuill and described as A. nidulans mut. alba. C, A. rugulosus NRRL No. 207, 

 characterized by heavy perithecium production, an almost complete absence of 

 conidial structures, and a tendency of colonies to split in central areas as shown. 

 D, A. variecolor NRRL No. 1954, characterized by the production of abundant large 

 perithecia. E, A. unguis NRRL No. 216, characterized by an absence of perithecia 

 and hulle cells. F, A. caespitosus NRRL No. 1929, characterized by the production 

 of masses of hiille cells suggesting abortive perithecia. 



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