ASCOMYCETES 
i5 
In species not provided with a true mouth the perithecium 
ruptures irregularly for the spores to escape. 
In the Discomycetes the ascus-bearing surface is not 
enclosed, but is fully exposed at maturity, seated on a flat or 
cup-shaped ascophore. 
The hymenial surface is composed of asci and paraphyses. 
All the asci are not developed at once. Their apices rarely 
reach the surface of the hymenium. The longer, slender, 
and often thread-like paraphyses extend above and protect 
them. (In a few cases the ascus at maturity is prolonged 
well above the surface of the disc.) The paraphyses border- 
Fig. 4. 
Hymenial surface of a Peziza (Dis¬ 
comycetes), showing the slender 
paraphyses surrounding the asci 
containing the spores (highly 
magnified). 
Fig. 5. 
A, section through a Xylaria 
(Pyrenomycetes), showing the 
numerous perithecia embedded 
in the stroma, with their mouths 
opening on to the surface of the 
fungus ; B, a perithecium, mag¬ 
nified. 
ing an ascus are pushed aside when a spore is being 
expelled, immediately afterwards regaining their former 
position. An ascus usually contains eight spores or some 
multiple of eight. Occasionally there are four spores in an 
ascus, rarely two, and very rarely one. 
The paraphyses vary greatly in shape, being either 
simple, branched, club-shaped, curved, or curled and con¬ 
torted. They are developed before the asci. Their sides 
are gelatinous, and afford a protective and well-lubricated 
channel, between which the asci thrust themselves. That 
the paraphyses are abortive asci seems probable, because 
