MOLDS 



55 



pale cream fruiting surfaces, Aspergillus flavus produces several shades 

 of yellow and green, Aspergillus ochraceus, ocher or tan. 



Much confusion is still found in the literature of this genus, so that 

 frequent references to the activities of particular species are difficult or 

 impossible to verify. 



CxADOSPORiuM (and Hormodendron) . — The species oi Clado- 

 sporium occur frequently in cultures of decaying vegetable matter, of 

 milk and cream, or butter. The colonies liquefy gelatin. . Both myce- 

 lium and spores are at first colorless, but later dark colored to almost 

 black, with spores becoming two-celled in very old cultures. 



Cladosporium herbarum is the commonest species encountered.* 



Fig. 36. Fig. 37. Fig. 38. 



Fig. 36. — Cladosporium herbarum, showing the forms of conidiophores and conidia 

 which are very common upon laboratory culture media. {Original.) 



Fig. 37. — Spores of Alternaria sp. {Original.) 



Fig. 38. — Fusarium from decaying potato, o, Spores showing curvature and 

 septa; 6, germination of spores; c, development of spores in petri-dish culture; d, 

 mass of spores as found in culture. (Original.) 



Colonies in culture media differ so greatly in structure from those upon 

 natural substrata as to make identification of species questionable. 

 Fig. 6. Much confusion is therefore found in the use of the names of 

 species of Cladosporium and the related genus, Hormodendron, which is 

 separated by some. 



Alternaria and Fusarium. — The frequent occurrence of species of 

 Alternaria and Fusarium in cultures demands that the generic charac- 

 ters be recognized. Both, as a rule, produce abundant growth with a 

 tendency to over-run cultures of other forms (Figs. 37 and 38). The 

 spores of Alternaria are brown, Indian-club form, muriform (divided 

 into several cells by longitudinal as well as cross- walls), and are con- 

 nected together into chains (Fig. 37). The spores of Fusarium are 



• This species has been shown to be a conidial form of Spharella tulasnei Janozewski, but 

 the bacteriological student will meet only the conidial stage. 



