THE ASPERGILLUS CLAVATUS GROUP 95 



among the strains examined by us and must be considered somewhat 

 atypical. It deserves particular attention because it was obtained from 

 the Centraal bureau in Baarn in 1908 as Aspergillus clavatus Desm. and has 

 undoubtedly been widely distributed by that organization — in fact, it is 

 quite probable that it has been examined by more investigators than any 

 other strain belonging to this group. We refrain from using it as a basis 

 for the species description, however, despite its classic history, since the less 

 floccose and more heavily sporing strains are so much more commonly 

 encountered in nature. 



Members of this species produce a strong alkaline reaction upon many 

 culture media and this is usually associated with a strong foetid odor. For 

 example, when grown upon Czapek's solution agar containing only NaN0 3 

 as nitrogen and sucrose as a carbon source, the reaction of typical strains 

 may reach pH 9.5 or even higher accompanied by a strong odor of tri- 

 methylamine almost approaching putridity. No other species of Asper- 

 gillus is known to react in this manner although some strains of A . flavipes 

 give some suggestion of it. The ability to produce, and more particularly 

 to withstand strong alkaline conditions undoubtedly accounts for the 

 common occurrence of this species upon dung and other nitrogen rich 

 substrata undergoing decomposition. 



Aspergillus giganteus Wehmer, in Central, f. Bakt., etc., 2, Abt. 18, No. 



13/15: 385. 1907. 



Colonies upon Czapek's solution agar growing rapidly at 20° C, charac- 

 terized by an extensive surface and submerged vegetative mycelium and an 

 early development of abundant conidiophores 2.0 to 4.0 mm. high, followed 

 by the subsequent development of less numerous conidiophores ranging up 

 to several centimeters in length (PI. Ill, B and Fig. 23 A), the latter 

 strongly phototropic and generally more abundant in marginal areas, com- 

 monly obscuring the more central mass of short conidiophores ; colonies at 

 first white, becoming pale blue-green as conidial heads mature ; reverse dull 

 tan, becoming brown in age; odor none to somewhat foetid in certain 

 strains. Conidial structures varying greatly in dimensions and falling for 

 the most part into two general size ranges: (1) conidiophores commonly 

 2 to 3 mm., rarely exceeding 4 mm. in height, bearing clavate heads 200 to 

 350/x in length; (2) conidiophores one to several centimeters in length, 

 bearing heads up to 1 mm. in length. The relative proportions of these 

 head types is strongly influenced by environmental conditions, and specific 

 strain characteristics. Conidial heads pale blue-green, in age splitting into 

 2 or more columns extending the length of the vesicle (Fig. 23 B). Vesicles 

 consisting of the expanded terminus of the conidiophore, ranging from 100 

 to 250m by 30 to 50m upon short conidiophores to 400 to 600m by 120 to 



