CHAPTER V. — COMPA RA TI VE RE VIE W. — A SCOMFCETES. — COLLEMA CEA E. 211 



covered on the 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 they are 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 toVanTieg- 

 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 

 recently confirmed by Eidam, 

 and rightly as far as I can 

 see. Some particulars are 

 still doubtful, and should be 

 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 perhaps 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 following 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 



FIG. 100. A, B Gyrophora cylindrical. A a vertical median section through a 

 spermogonium imbedded in the thallus ; o upper, u under rind, m medullary layer of 

 the thallus. B portion of a very thin section from the base of the spermogonium ; w 

 its wall from which proceed sterigmata with rod-like spermatia s, m medullary hyphae 

 of the thallus. C Cladonia Novae Angliae, Delise ; sterigmata with spermatia 

 1 from the spermogonium. After Tulasne. A magn. 90, B 390 times, C highly magnified. 



