MOLD OR HYPHOMYCETE GROUP 399 



The conidiophores are erect. Conidia are 5 to 7 p in diameter, 



Fig. 175. Aspergittus flavus: 1, 2, 3, 4, Various stages in the development 

 of conidiophores; 5, section and surface of a hypha, showing the numerous 

 colorless granules with which it is covered; 6, natural size of the fungus; 7, 

 conidia (Wehmer). 



globose. Spore masses are yellow and yellowish green. Sclerotia 

 are small and dark. 



Aspergillus niger 



This organism occurs under conditions similar to the preceding, 

 and is believed also to be pathogenic to horses and other animals 

 that consume grain infected with it. 



Morphology. The mycelium is at first white, then darker, 

 abundant, and penetrates the medium to a considerable distance. 

 The conidiophores are long and the spores borne up at some dis- 

 tance from the surface of the substratum. The sterigmata are 

 branched. The conidia are 3.5 to 4.5 ^ in diameter, roughened. 

 The spore masses ultimately become black, and may be readily 

 differentiated in this manner from the two preceding. This 



