ASCOMYCETES 279 



Conidial forms are numerous throughout the group, and 

 are very diversified in form and structure, and consequently 

 have received special names without end. In many in- 

 stances conidial stages have been proved to be an integral 

 part of an ascigerous form, by the only certain proof, that 

 of producing the conidial from the ascigerous form and 

 vice versa. In the majority of instances, however, relation- 

 ship between two forms is only assumed, the evidence 

 being that of contiguity, or the constant sequence of two 

 or more forms. 



The whole of the large assemblage of forms included 

 under ' Fungi imperfecti,' including the Hyphomycetes, 

 Melanconieae, and Sphaeropsideae, are usually considered 

 as hitherto unattached conidial forms of the Pyrenomy- 

 cetes. 



The Order includes two sub-orders, Pyrenomycetes and 

 Discomycetes. 



KEY TO THE SUB-ORDERS 



Hymenium or ascus - bearing surface permanently en- 

 closed in a hollow sporophore or perithecium, usually 

 furnished with a small ostiolum or opening, through which 

 the spores escape at maturity. When no specialised open- 

 ing exists, the sporophore eventually ruptures irregularly, 

 thus allowing the spores to escape. Pyrenomycetes. 



Hymenium or ascus-bearing surface fully exposed at 

 maturity, borne on a flat or cup-shaped sporophore. 



Discomycetes. 



In typical examples the two groups are readily recognised, 

 the most general form of perithecium in the Pyrenomycetes 

 resembling a flask with a very short neck, the ostiolum or 



