255 
of Poronia punctata (L.). 
in the middle, and the lateral hyphae gradually grow up 
through the stroma towards the surface, whilst from the base 
and sides of the swollen lower portions numerous septate 
filiform hyphae—the paraphyses—arise ; these grow up be¬ 
tween the ascogenous hyphae, and fill the cavity of the 
perithecium. The stouter ascogenous hyphae are still seen 
at the base, and in larger numbers than before; these, appa¬ 
rently by branching, give rise to the asci, which eventually 
line the perithecium in great numbers (cf. Figs. 24-26). 
The complicated nature of the perithecium at this stage, its 
thick wall and dense mass of paraphyses, make this point 
very difficult to demonstrate clearly, but a comparison of the 
stages observed in Poronia with those figured by Fisch 1 in 
Polystigma and Xylaria , makes it probable that the course of 
events is as described above. 
The mature perithecium consists of a very definite wall 
of closely interwoven hyphae lined with a smaller-celled 
hymenial layer, whence arise the very numerous club-shaped 
asci, intermingled with numerous paraphyses. The somewhat 
long neck, which opens by an ostiole to the exterior, is lined 
by delicate periphyses, which more or less completely fill the 
cavity leading into the perithecium (Fig. 26). 
It has been pointed out to me by Professor Marshall Ward 
that the observations at this stage suggest the possibility that 
the trichogyne-like hypha referred to above may be a sort of 
pioneer hypha to prepare the ostiole, and that it starts the disso¬ 
lution of the surrounding hyphae and so prepares the passage. 
A somewhat similar theory to the above was propounded 
in 1888 by Lindau 2 , in reference to the trichogynes developed 
by various Lichen-forming Fungi. At that time he regarded 
the trichogyne as partly sexual and partly mechanical in its 
function, but in 1899 3 he denied to the trichogyne, in the 
cases investigated by him, any sexual function, and described 
1 Fisch, Beitrage zur Entwickelungsgeschichte einiger Ascomyceten. Bot. Ztg., 
1882. 
2 Lindau, Ueber die Anlage und Entw. einiger Flechtenapothecien. Flora, 1888. 
3 See Darbishire, Pringsh. Jahrb. xxxiv, Heft 2, p. 330. 
