Introduction to Fungi, Third Edition

238 ASCOMYCOTA (ASCOMYCETES)
Fig 8.11 Ascus development in Ascobolus (after Oso,1969). (a) Young ascus showing the formation of membrane-bounded vesicles
(V) from the nucleus (N).The ascus wall (AW) is lined by the plasmalemma (PM). (b) Appearance of the ascospore membrane (AM)
at the tip of the ascus and the arrangement of vesicles along the periphery of the ascus. (c) Ascospore membrane now in the form of
a peripheral tube open at the lower end.The diploid nucleus has divided. (d) Invagination of the ascospore membrane between the
haploid nuclei. (e) Young ascospores (S) delimitedby the ascospore membrane from the epiplasm (E). (f) Separation of the two layers
of the ascospore membrane due to the formation of the primary spore wall (PSW) between them.
ascospore discharge as compared with singlespored
projectiles (Ingold & Hadland, 1959). This
adaptation is especially common in coprophilous
fungi, i.e. those which grow and fruit on
herbivore dung, such as Ascobolus (Fig. 14.5) and
Sordaria. A special adaptation occurs in another
coprophilous fungus, Podospora, in which the
basal part of the spore proper develops as a
primary appendage, whilst other parts of the
perispore extend as mucilaginous secondary