386 THE DEUTEROMYCETES (FUNGI IMPERFECTI) 



and the ascigerous stage of a goodly number of fungi. Quite 

 commonly cultures isolated from conidia s^ive rise to conidia in 

 culture, and cultures isolated from ascospores also give rise to 

 conidia. The production of ascocarps in cultures originating 

 either from conidia or from ascospores is of very much less com- 

 mon occurrence. The reasons for this situation are still largely 

 unknown. 



The structure of the conidial fructification in culture may be 

 quite different from that which characterizes the species when 

 it is grown on its natural substrate. Cultures of Septoria, a pyc- 

 nidial fungus, for example, may be hyphomycetous in that the 

 conidia are abstricted in succession from the apex of short, lateral 

 hyphal branches standing singly. Similarly, Cercospora in cul- 

 ture mav form conidia by successive acrogenous delimitation of 

 conidia from hvphal branches that stand singly, whereas in nature 

 the conidia are abstricted acropleurogenously from fasciculate 

 conidiophores. 



Classification. Several systems of classification of the Fungi 

 Imperfecti have been proposed. The oldest one, used by Sac- 

 cardo in Sylloge Fiingonnji, is serviceable and does not appear to 

 have been materially improved by the several modifications pro- 

 posed. In Saccardo's classification there are 4 orders, which may 

 be distinguished as follows: 



1. Conidia present 2 



2. Conidia in globoid, cupulate, or shield-sriaped pycnidia 



Phomales (Sphaeropsidales, Phyllostictales) 

 2. Conidia not in pycnidia 3 



3. Conidiophores short and aggregated at the surface of a thin 



parenchvmoid stroma (an acer\'ulus) Melanconiales 



3. Conidiophores varvdng in length but not on an acervulus, 

 formed singly in fascicles or on sporodochia (cushion-shaped 

 structures) Moniliales (Hyphomycetes) 



1. Conidia lacking Mycelia Sterila 



The Phomales comprise 4 families, separated as follows: 



1. Pycnidia globoid 2 



2. Pycnidia brown or black, membranaceous or carbonaceous 



Phomaceae (Sphaeropsidaceae) 

 2. Pycnidia hyaline or bright-colored, soft, fleshy, or waxy 



Zvthiaceae (Nectrioidaceae) 

 1. Pycnidia shield-shaped, sometimes radiately constructed 



Leptostromataceae 



