CHAPTER III. SPORES OF FUNGI. 97 



ascus-wall which surrounds them, and the protoplasm disappearing they at length 

 entirely fill the cavity of the ascus ; the wall of the ascus then forms a delicate septum 

 between each pair of spores, and not unfrequently appears constricted between each 

 pair c, but the septa are at length broken through in Sphaerophoron and most of the 

 Calycieae, and the spores are thereby set free from one another and are collected 

 together as a loose dust on the surface of the hymenium. In Lichina and Paulia the 

 spores remain firmly united together. 



The phenomenon which we are considering is very common in asci which ripen 

 in closed receptacles. Chaetomium (Zopf) and Melanospora parasitica 1 may be 

 mentioned first as trustworthy examples among the Pyrenomycetes. In these species 

 the wall of the ascus swells when the spores are ripe into a copious jelly, which increases 

 in volume by absorption of water to such an extent that it issues out of the orifice of 

 the perithecium and brings out with it the spores which are imbedded in it. The 

 tissue surrounding the asci also swells up and adds to the quantity of jelly employed 

 in the way described. The mass of spores thus forced out of the perithecium collects 

 at its orifice in the form of drop-like aggregations or twisted tendril-like filaments like 

 a tough mass squeezed through a narrow tube. This mode of emptying of asci and 

 perithecia is very common in Pyrenomycetes with thin-walled asci, occurring probably 

 in species of Nectria 2 , in Hypoxylon concentricum, Nummularia, Stictosphaeria, 

 Eutypa, Quaternaria, and many other Xylarieae and Valseae described by Tulasne 3 . 

 But more exact observation of individual cases is still required with reference to the 

 considerations mentioned in this section. Perithecia without an orifice like those of 

 Chaetomium fimeti and Cephalotheca tabulata * burst by the swelling of the gelatinous 

 substance in a fixed manner. 



The asci of Eurotium, Penicillium, Anixia truncigena 5 , Onygena, Elaphomyces, 

 and the Tuberaceae, which are also developed in closed receptacles but with no natural 

 aperture, and opening only in consequence of decay or some accidental lesion, are 

 dissolved or decomposed sometimes after temporary gelatinous swelling ; they disappear 

 entirely and allow the spores to enter free and unconnected into the cavity of the 

 receptacle. 



SECTION XXVIII. The liberation of the spores takes place in almost all 

 cases as soon as they have reached maturity, that is as soon as they are fully devel- 

 oped, and this as a rule precedes the commencement of germination. In the few excep- 

 tions to the rule, which are rendered more remarkable by its generality and apparent 

 necessity, the spores when they are liberated from the ascus increase considerably in 

 size either at the expense of their environment or of the reserve material which they 

 themselves contain, till they have reached the degree of development which strictly 

 corresponds to the state of maturity. Elaphomyces is specially noteworthy in this 

 respect 6 , in which the spores, after they are set free from the perishing asci, grow to 



1 Kihlmann, Zur Entw. d. Ascomyceten (Act. soc. Fennicae), XIII, 1883. 



2 Janowitsch in Bot. Ztg. 1865. 



3 Carpol. II. 



* Zopf in Sitzgber. d. nalurf. Freunde, see p. 85, and for Chaetomium, Nov. Act. Acad. Leopold 

 Bd. 42, Nr. 5 (1881). 



5 H. Hoffmann, Icon. Analyt. Ill, p. 70. 



6 See De Bary. Fruchtentw. d. Ascomyceten, p. 33. 



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