THE SPORE AND ITS DISSEMINATION. 131 
In the Perisporiacei the perithecinm has no proper orifice, or 
ostiolum, for the discharge of the mature sporidia, which are 
usually small, and are disseminated by the irregular rupture of 
the somewhat fragile conceptacles. The asci are usually more 
or less saccate, and the sporidia approximate to a globose form. 
The asci are often very diffluent. In Perisporiuim vulgare the 
ovate brown sporidia are at first, and for some time, attached 
together in fours in a concatenate or beaded manner. In some 
species of Erysiphei the conceptacle en- 
closes but a single sporangium, in others 
several, which are attached together at the 
base. In some species the sporangia contain 
two, in others four, in others eight, and in 
others numerous sporidia. In Chetomium 
the asci are cylindrical, and in most cases 
the coloured sporidia are lJemon-shaped. 
When the conceptacles are fully matured, 
it is commonly the case that the asci are 
absorbed and the sporidia are free in the 
interior of the conceptacles. 
Of the fleshy Discomycetes the genus 
Peziza may be taken as the type. If the 
structure which prevails in this genus be 
brought to mind, it will be remembered 
that the hymenium lines an expanded cup, 
and that the asci are packed together, side 
by side, with their apices outwards, and 
their bases attached to a substratum of cells 
which form the inner layer of the recep- 
tacle. The sporidia are usually eight in 
each ascus, either arranged in single or 
double rows, or irregularly grouped to- 
gether. The asci are produced in succes- 
Fic, 66.—Asc’, sporidia, 
sion ; the later, pressing themselves upwards and paraphyses of Asco- 
between those previously developed, cause 
bolus (Boudier). 
the rupture of the mature asci at the apex and the ejection of 
the sporidia with considerable force. When a large Pe:iza is 
