FUNGI. -CLEISTOCARPOUS ASCOMrCETES. 



105 



antheridial branch (IV, h] in close contact with the archicarp and unite in an arch 

 over its apex ; the filaments then become pluricellular by transverse divisions, and 

 close up laterally, forming a pseudo-parenchyma. As the investment increases in size 

 it puts out short branches from its inner side, and these fill up the now enlarged space 

 between it and the archicarp which has as yet grown but little larger (see Fig. 65, 

 V, ft). Then the still unicellular archicarp begins to enlarge and is divided by a 

 transverse septum into a lower and an upper cell ; the former may be considered to be 

 the simplest case of an ascogenous filament, the apical cell of which becomes an ascus 

 at once ( V^ a). Eight spores arise by free cell-formation in the protoplasm of the ascus, 

 which increases in size and ultimately fills up the space inside the envelope, and will 

 slip out from it if the fructification is squeezed (77, a). In other Erysipheae, as E. 

 Umbelliferarum, communis, lamprocarpa and others, where the fruits contain several 

 asci, the archicarp, here too at first unicellular, grows inside the envelope to a long, 

 thick, curved filament, which is divided by several transverse septa ; then several of 

 the cells thus formed put out short lateral branches, and these produce the asci. 



The Erisypheae with several asci furnish a transition to the Eurotieae, in which the 



W p 



FIG. 65. /, // Podosphaera pannosa. 1 Gonidiophore. with gonidial chain. // Ripe fructification after Tulasne. 

 Podosphaera Castagnei. Ill Archicarp and antheridial branch. IV the same at commencement of the formation of 

 the fructification. Kthe young fructification ; c archicarp, p antheridial branch, h envelope of the fruit, a the single 

 ascus. After de Bary, magn. 600 times. 



archicarp elongates considerably before fertilisation, and in doing so is twisted like 

 a corkscrew. 



b. The history of the development of Eurotium repens and Eurotium Asper- 

 gillus glaucus has been described in detail by De Bary. Both these species live in 

 decomposing organic substances of very various kinds, and especially in preserved fruit. 

 In the latter case the fungus covers the surface of the fruit with a delicate white floccu- 

 lent mycelium, from which gonidiophores soon begin to rise in large numbers ; these 

 swell at their upper extremity into a globular form, and from the upper half of the globe 

 a number of conical projections, the sterigmata, arise, closely crowded and radially 

 disposed. Each of these projections gradually produces a long chain of greenish 

 gonidia, and at length the head of the gonidiophore is covered with a thick layer of 

 them. During the production of the gonidia sexual organs are being formed on the 

 same mycelium. The archicarp is the corkscrew-like extremity of a branch of the 

 mycelium (Fig. 66, A, as), the turns of which approach nearer and nearer to each other, 

 till at length they touch and form a hollow screw (C, D). During this proceeding 

 about as many delicate transverse septa make their appearance as there are turns of the 

 screw, namely, from five to six. Two slender branches then shoot out from two opposite 



