110 



THE FUNGI IMPERFECT! AND THE ASCOMYCETES 



Fusarium. Fusarium is a large, widespread, and very difficult 

 genus. Forty-odd species and many more varieties have been found 

 in soil and frequently they are encountered as air contaminants. 

 ]\Iany other species are of considerable importance as the cause of 

 diseases of plants. One species, Fusarium oxysponim, has been 

 widely distributed in culture among bacteriologists, bearing the label 

 Trichophyton rosaceum, and this culture, supposedly a dermatophyte, 



Fig. 62. Fusarium Equiseti: above, macroconidia ; middle, mycelium; below, 

 microconidia. XIOOO. Camera lucida drawing bj^ Dr. Roderick Sprague. 



but actually a saprophyte," has been used extensively to test sub- 

 stances designed to be used in the treatment or prevention of fungus 

 infections of man. Conidiophores arise in verticillate arrangement 

 from short hyphal branches. On these are borne long fusiform or 

 sickle-shaped multinucleate conidia. The crosswalls of the conidia 

 are frequently somewhat indistinct. In addition to these large multi- 

 nucleate conidia, often designated macroconidia, several species pro- 

 duce also small, one- or few-celled, egg-, pear-, spindle- or kidney- 

 shaped microconidia. See Fig. 62. The perfect stage is known in 

 several species. The genus Fusarium has been monographed by 

 Wollenweber and Reinking.^^ 



Cladosporium (Hormodendrum). One not infrequently finds as 

 a contaminant on Petri plate cultures a rather small dark olive- 



