THE ASPERGILLUS CLAVATUS GROUP 



93 



heavy walled, smooth, 3.0 to 4.0/x by 2.0 to 3.0/j, ocasionally larger in some 

 strains and irregular in others. 



D 



Fig. 21. Aspergillus clavatus Desm. A, Colony growing on Czapek's solution 

 agar, 10 days, room temperature, X 1.3 (Thorn No. 5169). B, Conidial heads showing 

 characteristic splitting in age, X 12 (Strain NRRL No. 1823). C, Conidial heads 

 showing characteristic clavate form of vesicle, X 180 (Strain NRRL No. 6). D, 

 Portion of a conidial head further enlarged, showing closely packed single series of 

 sterigmata, X 600 (Strain NRRL No. 6). 



Cosmopolitan in distribution and especially common in soil, decaying 

 vegetation, dung and other materials where active decomposition of nitrog- 

 enous materials is taking place. Cultures examined include numerous 



