Fungi: Their Nature and Uses

by M. C. Cooke

Here, then, we have undoubted evidence of Nectria cinnabarina, with its fruit, produced in asci growing from the stroma or stem, and in intimate relationship with what was formerly named Tubercularia vulgaris. A fungus with two forms of fruit, one proper to the pink, or Tubercularia form, with naked slender conidia, the other proper to the mature fungus, enclosed in asci, and generated within the walls of a perithecium. Instances of this kind are now known to be far from uncommon, although they cannot always, or often, be so clearly and distinctly traced as in the illustration which we have selected.

Fig. 106.—D. Nectria surrounding Tubercularia; E. tuft of Nectria cinnabarina; F. section of stroma; G. ascus and paraphyses.

It is not uncommon for the conidia of the Sphæria to partake of the characteristics of a mould, and then the perithecia are developed amongst the conidial threads. A recently recorded instance of this relates to Sphæria Epochnii, B. and Br.,[L] the conidia form of which was long known before the Sphæria related to it was discovered, under the name of Epochnium fungorum. The Epochnium forms a thin stratum, which overruns various species of Corticium. The conidia are at first uniseptate. The perithecia of the Sphæria are at first pale bottle-green, crowded in the centre of the Epochnium, then black green granulated, sometimes depressed at the summit, with a minute pore. The sporidia are strongly constricted in the centre, at first uniseptate, with two nuclei in each division.

Another Sphæria in which the association is undoubted is the Sphæria aquila, Fr.,[M] which is almost always found nestling in a woolly brown subiculum, for the most part composed of barren brown jointed threads. These threads, however, produce, under favourable conditions, mostly before the perfection of the perithecia, minute subglobose conidia, and in this state constitute what formerly bore the name of Sporotrichum fuscum, Link., but now recognized as the conidia of Sphæria aquila.

In Sphæria nidulans, Schw., a North American species, we have more than once found the dark brown subiculum bearing large triseptate conidia, having all the characters of the genus Helminthosporium. In Sphæria pilosa, P., Messrs. Berkeley and Broome have observed oblong conidia, rather irregular in outline, terminating the hairs of the perithecium.[N] The same authors have also figured the curious pentagonal conidia springing from flexuous threads accompanying Sphæria felina, Fckl.,[O] and also the threads resembling those of a Cladotrichum with the angular conidia of Sphæria cupulifera, B. and Br.[P] A most remarkable example is also given by the Brothers Tulasne in Pleospora polytricha, in which the conidia-bearing threads not only surround, but grow upon the perithecia, and are crowned by fascicles of septate conidia.[Q]

Instances of this kind have now become so numerous that only a few can be cited as examples of the rest. It is not at all improbable that the majority of what are now classed together as species under the genus of black moulds, Helminthosporium, will at some not very distant period be traced as the conidia of different species of ascomycetous fungi. The same fate may also await other allied genera, but until this association is established, they must keep the rank and position which has been assigned to them.

Another form of dualism, differing somewhat in character from the foregoing, finds illustration in the sphæriaceous genus Melanconis, of Tulasne, in which the free spores are still called conidia, though in most instances produced in a sort of spurious conceptaculum, or borne on short threads from a kind of cushion-shaped stroma. In the Melanconis stilbostoma,[R] there are three forms, one of slender minute bodies, oozing out in the form of yellow tendrils, which may be spermatia, formerly called Nemaspora crocea. Then there are the oval brown or olive brown conidia, which are at first covered, then oozing out in a black pasty mass, formerly Melanconium bicolor, and finally the sporidia in asci of Sphæria stilbostoma, Fries. In Melanconis Berkeleii, Tul., the conidia are quadrilocular, previously known as Stilbospora macrosperma, B. and Br. In a closely-allied species from North America, Melanconis bicornis, Cooke, the appendiculate sporidia are similar, and the conidia would also appear to partake of the character of Stilbospora. We may remark here that we have seen a brown mould, probably an undescribed species of Dematiei, growing in definite patches around the openings in birch bark caused by the crumpent ostiola of the perithecia of Melanconis stilbostoma, from the United States.

In Melanconis lanciformis,[S] Tul., there are, it would appear, four forms of fruit. One of these consists of conidia, characterized by Corda as Coryneum disciforme.[T] Stylospores, which are also figured by Corda under the name of Coniothecium betulinum; pycnidia,[U] first discovered by Berkeley and Broome, and named by them Hendersonia polycystis;[V] and the ascophorous fruits which constituted the Sphæria lanciformis of Fries. Mr. Currey indicated Hendersonia polycystis, B. and Br., as a form of fruit of this species in a communication to the Royal Society in 1857.[W] He says this plant grows upon birch, and is in perfection in very moist weather, when it may be recognized by the large black soft gelatinous protuberances on the bark, formed by spores escaping and depositing themselves upon and about the apex of the perithecium. This I suspect to be an abnormal state of a well-known Sphæria (S. lanciformis), which grows upon birch, and upon birch only.

We might multiply, almost indefinitely, instances amongst the Sphæriacei, but have already given sufficient for illustration, and will therefore proceed briefly to notice some instances amongst the Discomycetes, which also bear their complete or perfect fruit in asci.