CHAPTER XXII 

 FUNGI IMPERFECTI (DEUTEROMYCETES) 



The life histories of the fungi belonging to this group are imperfectly 

 known, and hence, it happens that when it has been established, the 

 type is removed from the fungi imperfecti and properly classified with 

 some other group. The name Deuteromycetes, also applied to the 

 imperfect fungi, is derived from the Greek, Bevrepos = second. Many 

 important parasites are included here, and hence, it has been considered 

 important by mycologists to give the characters by which the fungi 

 imperfecti are distinguished. 



General Characters. — The mycelium consists of septate, hyaline, or 

 pigmented hyphse, or only of chain of yeast-like cells. The hyphae are 

 diffuse, or plectenchymatous (xXe/cros = woven). Stromata are fre- 

 quently present. The fructification is a single conidiophore, a layer 

 of conidiophores, or a conidial fructification (pycnidium). The 

 Fungi Imperfecti represent the accessory fruit forms of the ASCOMY- 

 CETALES, rarely those of other orders. The mycelium is practically 

 the same as found in the sac fungi. The septate hyphae spread over 

 the substratum, or penetrate its interior, and the fungi live sapro- 

 phytically, or parasitically. The arrangement of the hyphae in various 

 ways has suggested the segregation of species and genera. The under 

 layer (subiculum = felted stratum of hyphae) is of loose, entangled 

 threads, or disc-like bodies, or radially stretching fibrils, aggregated 

 loosely. The stroma on the contrary represents compact tissue, cor- 

 responding to similarly named structures in the ASCOMYCETALES. 

 The fruit layer originates in or on the stroma. 



Reproduction is dependent on exogenously produced spores, known 

 as conidiospores. In the simplest cases, the mycelium gives rise at 

 indefinite places to outgrowths, which are separated as spores. There 

 arise from the mycelium, erect conidiophores which form conidiospores 

 in the different species. With an unbranched conidiophore, the conidio- 

 spores arise at its apex followed by a second, a third, etc. When the 

 end of the conidiophore is globular, the spores arise on the ends of 

 sterigma. By the branching of the conidiophores originate conidial 



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