78 FUNGI. 
hymenium soon becomes exposed. In some instances, there is 
a close affinity with the ivellacei, the exposed hymenium being 
similar in structure, but in ail the disc is at first closed. In 
orbicular forms, the fissure takes place in a stellate manner from 
the centre, and the teeth are reflexed. In the Hysteriacei, where 
the perithecia are elongated, the fissure takes place throughout 
their length. Asarule, the sporidia are more elongated, more 
commonly septate, and more usually coloured, than in Elvellacei. 
Only a few solitary instances occur of individual species that 
are parasitic on living plants. 
In the Spheriacei, the substance of the stroma (when pre- 
sent) and of the perithecia is vari- 
able, being between fleshy and waxy 
in Nectriei, and tough, horny, some- 
times brittle, in Hypoxylon. A peri- 
thecium, or cell excavated in the 
stroma which fulfils the functions of 
Dee a perithecium, is always present. 
i Ge ie The-hymenium lines the inner walls 
“ws _ of the perithecium, and forms a gela- 
tinous nucleus, consisting of asci and 
paraphyses. When fully mature, the asci are ruptured and the 
sporidia escape by a pore which occupies the apex of the peri- 
thecium. Sometimes the perithecia are solitary or scattered, and 
sometimes gregarious, whilst in other instances they are closely 
aggregated and immersed in a stroma of variable size and form. 
Conidia, spermatia, pycnidia, &c., have been traced to and asso- 
ciated with some species, but the history of others is still obscure. 
Many of the coniomycetous forms grouped under the Spheronemet 
are probably conditions of the Spheriacei, as are also the Melan- 
coniei, and some of the Hyphomycetes. A very common fungus, 
for instance, which is abundant on sticks and twigs, forming 
rosy or reddish pustules the size of a millet seed, formerly 
named Tubercularia vulgaris, is known to be the conidia-bearing 
stroma of the spheriaceous fungus, Wectria cinnabarina ; * and so 
Fic. 42.—Spheria aquila. 
* A Currant Twig and Something on it,” in ‘‘Gardener’s Chronicle ” for 
January 28, 1871. 
