ASCOMYCETES 



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injured, and may germinate after a period of rest, forming at first 

 fresh superficial mycelium and conidia ; but, later on, outgrowths 

 may spring directly from them, as in some species of Peziza, which 

 bear broad disc-like fruits. Those Ascomycetes which have such 

 flat open fruits as are seen in Peziza are ranked as Discomycetes 

 (Fig. 322). The most notorious sclerotia are those of Claviceps 



Fig. 322. 



A, a sclerotium of Peziza, which has germinated and 

 given rise to numerous trumpet-shaped discs. B, section 

 through such a sclerotium (sc), and the Peziza disc (d) to 

 which it has given rise. b= stalk. a=asci. Magnified 

 and slightly diagrammatic. (From Marshall Ward.) 



purpurea, the Ergot of Rye, a fungus which causes a disease on 

 Rye-crops. The fungus attacks the ovaries of the Rye and other 

 Grasses at the flowering period, spreading over them and causing 

 the condition known as " Honey-Dew." This is the conidial stage, 

 and it is spread from plant to plant by insects, which are attracted 

 by a sugary secretion in which the conidia float (Fig. 323, a, b ; 

 also Fig. 293, p. 395). But the effect becomes more apparent as the 

 Rye-crop ripens, for in place of the normal grains long curved bodies 

 project from the ear (Fig. 323, c). These are the sclerotia of the fungus, 

 which fail off at the time of ripening of the grain. They are the 

 commercial source of supply of a useful drug. In this resting stage 

 the winter is passed. In spring the sclerotia germinate, forming 

 numerous pinhead-like growths, which bear the flask-shaped peri- 

 thecia characteristic of the large group of the Pyrenomycetes (Fig. 323, 

 d, e). Finally in these the asci and thread-like ascospores are 

 matured at about the time when the Grasses flower. It has been 

 proved experimentally that hyphae from the germinating ascospores 



