CHAPTER V. — COMPARATIVE REVIEW. — ASCOMVCETES. 245 



and some others. Ripe and ripening perithecia may in these plants stand side by 

 side on the same mycelium or stroma with developing gonidiophores. 



It is scarcely necessary to remark that the succession of events does not always 

 proceed in these examples with perfect regularity; and the instance of Peziza 

 Fuckeliana described above on page 224 shows that considerable deviations from it 

 may and do occur. 



As regards the point of origin of the gonidiophores and their arrangement and 

 structure, it would seem that they occur in particular species in the ascocarps them- 

 selves, like the doubtful spermatia noticed on page 242. According to Berkeley 1 

 single paraphyses are found between the asci in Sphaeria oblitescens B. et Br., in which 

 one or two of the cells are enlarged into somewhat elongated septate ' spores ; ' the 

 terminal cells of such paraphyses in Dothidea Zollingeri, Berk. 2 are like simple 

 ellipsoid spores. Berkeley 3 makes a similar statement in the case of a species of 

 Tympanis and for Lecidea Sabuletorum 4 or an allied form ; but these points require 

 re-examination, as Tulasne has intimated 5 , because we are still ignorant of the 

 qualities of these spore-like bodies. 



Putting aside these few doubtful and possibly exceptional cases, all gonidial 

 formations conform to the examples described above which have been thoroughly 

 examined. The following special forms may be enumerated : — 



(a) Free filiform gonidiophores ; often very characteristic in their conformation, 

 as in Penicillium, Eurotium, Erysiphe, &c, and in such cases formerly assigned to 

 established form-genera. Thus species of Hypomyces were assigned to the form- 

 genera Verticillium, Sepodonium, and Mycogone of the old descriptions, and 

 Fusisporium Solani 6 ; species of Nectria to Fusisporium and Spicaria of the old 

 descriptions, and many other cases might be cited. To these may be added some 

 other forms, in which the distinction between gonidia and gonidiophores on the one 

 hand and portions of the mycelium on the other is less sharply defined, and may even 

 be arbitrary in each individual instance up to the extreme cases in which each cell 

 of a hypha or a hyphal strand first performs the part of a mycelium and then 

 assumes the characters of a spore. The latter is in extreme cases naturally 

 termed the formation of resting mycelium and has been elaborately studied by Bauke 

 and Zopf, especially in saprophytic Pyrenomycetes, though older observers often men- 

 tioned it incidentally. It occurs in old and specially in starved mycelia for example 

 of Pleospora, Fumago, and Cucurbitaria, in which the cells of the mycelium 

 acquire thick and usually brown walls, store up reserve food material, and pass into a 

 dormant state, and subsequently under suitable conditions germinate as spores. 

 Changes of form, especially swelling of the individual cells into a spherical shape, may 

 or may not accompany the changes which characterise the state of rest, and hence the 

 resting states differ in very various degrees from the vegetative mycelial forms. 



1 Ann. Mag. Nat. hist. ser. 3, III, p. 373, t. XI, 32. 



2 Hooker's Journ. Ill (1844), p. 336. 



3 Introd. Crypt. Bot. p. 244. 



4 See Ann. Mag. Nat. Hist. ser. 2, IX, and Crypt. Bot. p. 391. 



5 Mem. s. les Lichens, p. no. 



fi Reinke u. Beithold, Die Zersetzung d. Kartoffeln durch Pilze, 1879. 



