STRUCTURE. 59 
movement, suffices to cause dehiscence, which is generally 
followed by a scarcely perceptible contractile motion of the 
receptacle. 
There is manifestly a succession in formation and maturity of 
the asci in a receptacle. In the true Ascobolei, in which the 
sporidia are coloured, this may be more dis- 
tinctly seen. At first some thin projecting 
points appear upon the disc, the next day 
they are more numerous, and become more 
and more so on following days, so as to 
render the disc almost covered with raised 
black or crystalline points ;* these after- 
wards diminish day by day, until they ulti- 
mately cease. The asci, after separation 
from the subhymenial tissue, continue to 
lengthen, or it may be that their elasticity 
permits of extension during expulsion. 
Bondier considers that an amount of elas- 
ticity is certain, because he has seen an 
ascus arrive at maturity, eject its spores, 
and then make a sharp and considerable 
movement of retraction, then the ascus re- 
turned again immediately towards its pre- 
vious limits, always with a reduction in the 
number of its contained sporidia. 
The dehiscence of the asci takes place in 
the Ascobolei, in some species of Peziza, 
Morchella, Helvella, and Verpa, by means 
of an apical operculum, and in other Pezize, 
Helotium, Geoglossum, Leotia, Mitrula, &c., Fe eres siane, pari 
by a fissure of the ascus. This operculum %¥ (Boudier'. 
may be the more readily seen when the ascus is coloured by a 
drop of tincture of iodine. 
The sporidia are usually four or eight, or some multiple of 
that number, in each ascus, rarely four, most commonly eight. 
At a fixed time the protoplasm, which at first filled the asci, dis- 
* Only in some of the Discomycetes are the asci exserted. 
