THE ASPERGILLUS NIDULANS GROUP 



167 



characterized particularly by clusters of irregular ovoid to elliptical, thick- 

 walled hulle cells, at first colorless becoming reddish-purple in age, scattered 



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Fig. 45. Aspergillus caespitosus ; , NRRL No. 1929. A, Portion of colony on 

 Czapek's solution with 1 percent liver extract, showing crowded conidial heads in 

 central portion and scattered hulle cell masses in surrounding areas, two weeks old, 

 incubation at room temperature, X 1.8. B, Portion of colony enlarged showing 

 hulle cell masses, X 10. C, Silhouettes of conidial heads developed on hay infusion 

 agar, X 48. D, Typical conidial head showing form of vesicle and arrangement of 

 sterigmata, X 600. E, Portion of htille cell mass showing irregular size and form 

 of component elements, X 265. (Reprinted from Raper and Thorn, "New Species 

 of Aspergilli from Soil," Mycologia 36: Nov.-Dec. 1944.) 



unevenly (fig. 45 A and B) or arranged in irregular concentric zones; reverse 

 colorless at first, becoming dark reddish-purple in age, particularly beneath 

 the hulle masses; odor none. Conidial heads dark dull yellow-green to 



