192 DIVISION II.—COURSE OF DEVELOPMENT OF FUNGI, 
in Diatrype, Verrucaria, Endocarpon, Pyrenula, and in a very striking manner 
in Massaria and its nearest allies. In the latter the perithecia are formed inside 
a flat stroma which lives in the rind of trees, and the orifice is due to the disorgan- 
isation and ultimate disappearance of a comparatively thick strip of tissue outside 
and over the apex of the perithecium, together with the tissue of the rind enclosed 
by it. 
The neck is of course a prolongation of the wall, chiefly of its outer layers; this 
appears very distinctly in some perithecia developed in the interior of the thallus, as 
in Xylaria, the Valseae, Verrucaria, Endocarpon, and species of Pyrenula’, where 
it pierces through the surface of the thallus and comes out to the air. Its de- 
velopment is either rapidly completed at an early period, or it is capable under 
certain conditions of a long-continued apically progressive or intercalary growth 
in length, and while this is proceeding it is, especially in Sordaria?, in a high 
degree heliotropic; this variety in the mode of development depends on the species 
and genus. 
The asc¢ are inserted in the places in the delicate tissue of the inner wall 
which have been already indicated, and the ascogenous hyphae or cells are thrust 
in between the elements of the wall or lie immediately upon them. The asci 
fill the inner space of the perithecium, or at least the largest part of it, excepting the 
neck. All the space not occupied by them is filled with branches of the hyphae, 
which grow out from the inner layer of the wall toward the median line of the 
perithecium. Some of these branches lie between the asci, and are then termed 
paraphyses, as in the Discomycetes, and stand in the same relation as regards their 
development to the asci as in the Discomycetes, since as parts of the envelope 
they are formed before the asci which are afterwards introduced between them. 
Others may cover the portion of the perithecium which -is without asci, and 
even the canal, and then they are called by Füisting periphyses. In the canal they 
are like small closely set hairs of uniform height, which converge from all sides and 
are directed obliquely upwards towards the median line of the canal where their 
extremities almost touch. Below the inner (lower) entrance of the canal, in the 
part of the perithecial cavity where there is no hymenium, their direction and arrange- 
ment either remain the same as in the canal, as in Chaetomium and Sordaria 
fimiseda, or they point downwards towards the median line and the hymenium 
(Fig. 90). Periphyses would appear to be seldom entirely wanting, though this is 
sometimes the case, according to Fiiisting, as in some species of Massaria. 
It more frequently happens that there are no paraphyses between the asci, 
and then the asci alone constitute the hymenium; this is the case in Sordaria, 
Melanospora, Claviceps, Epichlo&, Chaetomium (Zopf), Sphaeromphale, and species of 
Dermatocarpon, Endocarpon, and Verrucariae (Winter, Füisting). Further details 
will be found in special treatises, though the accounts there given must often be 
received with caution, for the paraphyses and periphyses and other organs are often 
delicate and perishable, or easily overlooked or confounded if the observations are 
not conducted with sufficient care, and thus mistakes may often be made, especially 
if the material is not in a favourable state and the observer is wanting in experience. 

1 Bot. Ztg. 1868, p. 641. 2 Woronin, Beitr. II. 
