CHAPTER V.—COMPARATIVE REVIEW.—ASCOMYCETES.—COLLEMACEAE. 211 
covered on ihe inside with periphyses which converge towards the median line. All 
the periphyses, those of the neck as well as those beneath it, converge till their 
extremities touch, but without becoming firmly united, so that asci or spores can pass 
between them to the outside when theyare mature. In Melanospora parasitica the future 
canal of the ostiole is to some extent marked out from the first, for the non-ascogenous 
basal cells of the spiral archicarp, that is the cells turned towards the place of insertion, 
remain in their place as large vesicles, together forming a strand outside which the 
periphyses which converge towards it afterwards spring from the wall. Then the 
neck also grows in the direction of the strand outwards at the place of insertion of 
the perithecium or archicarp, while the vesicles are ejected as disorganised masses 
of mucilage. In Sordaria it would appear that the canal of the ostiole and the neck 
are formed on the side diametrically opposite to the place of insertion of the perithe- 
cium ; the first simply in consequence of corresponding surface extension of the young 
wall, and as an intercellular space which is at once filled with the periphyses; the 
formation of the neck has been less exactly studied. 
According to Van Tieg- 
hem’s observations Chaeto- 
mium is nearly related to 
the forms which we have 
been considering. The con- 
clusions of this writer have, 
it is true, been stoutly as- 
sailed by Zopf, but on the 
other hand they have been 
recentlyconfirmedbyEidam, 
and rightly as far as I can FIG. 100. A, B Gyrophora cylindrica. A a vertical median section through a 
spermogonium imbedded in the thallus; o upper, # under rind, » medullary layer of 
see. Some particulars are the thallus. 2 portion of a very thin section from the base of the spermogonium; w 
: its wall from which proceed sterigmata with rod-like spermatia s, 7 medullary hyphae 
still doubtful, and should be fobs sperogoniam, After Tose: magn so 5p tines ChgDy gta, 
submitted to further exam- 
ination with due reference to the works of these observers. The latter remark will 
apply also to Bainier’s short description of some species of Ascotricha examined 
by him and ferhaps belonging to this place; I have not been able clearly to 
understand his account of them. 
8. The development of the apothecia in the Discomycetes which are included 
in the group of the Collemaceae is in all points similar, according to Stahl’s 
observations, to those which have just been described. But it is preceded by 
fertilisation of the archicarp by spermatia formed at a distance from it, and this 
causes the fcllowing modifications. 
The Collemaceae form a gelatinous Lichen-thallus with lobe-like branches (see 
section CXVI. 5). Sections through the thallus show much-branched hyphae loosely 
distributed and interwoven in the thick gelatinous membrane-substance; the branches 
are also closely united together at certain spots in the fertile thallus in order to form 
the receptacles which produce the spermatia, and which were first clearly distinguished 
by Tulasne as spermogonia. These organs, of which Fig. 100 below will give some 
idea, though taken from other species, are in the mature state small bodies, but visible 
to the naked eye, having very much the shape of the flask-shaped perithecium of the 
P 2 

