Under the name of Stylospores may be classed those spores which in some orders of Coniomycetes are produced at the apex of short threads, either enclosed in a perithecium, or seated upon a kind of stroma. These are exceedingly variable, sometimes large, and multiseptate, at other times minute, resembling spermatia. In such genera as are chiefly epiphytal, in Septoria, Phyllosticta, and their allies, the minute spores are enclosed within membranaceous perithecia, and when mature these are ejected from the orifice at the apex, or are exposed by the breaking off of the upper portion of the perithecia. In Diplodia and Hendersonia the spores are larger, mostly coloured, often very fine in the latter genus, and multiseptate, escaping from the perithecia by a terminal pore. Probably the species are only pycnidia of Sphæriacei, but that is of no consequence in relation to our present inquiry. Of stylospores which deserve mention on account of their singularity of form, we may note those of Dilophospora graminis, which are straight, and have two or three hair-like appendages at each extremity. In Discosia there is a single oblique bristle at each end, or at the side of the septate spores, whilst in Neottiospora a tuft of delicate hairs is found at one extremity only. The appendages in Dinemasporium are similar to those of Discosia. The spores in Prosthemium may be said in some sort to resemble compound Hendersonia, being fusiform and multiseptate, often united at the base in a stellate manner. In this genus, as in Darluca, Cytispora, and the most of those belonging to the Melanconiei, the spores when mature are expelled from the orifice of the perithecium or spurious perithecium, either in the form of tendrils, or in a pasty mass. In these instances the spores are more or less involved in gelatine, and when expelled lie spread over the matrix, around the orifice; their ultimate diffusion being due to moisture washing them over other parts of the same tree, since it is probable that their natural area of dissemination is not large, the higher plants, of which they are mostly conditions, being developed on the same branches. More must be known of the relations between Melanconium and Tulasne’s sphæriaceous genus Melanconis before we can appreciate entirely the advantage to Melanconium and some other genera, that the wide diffusion of their spores should be checked by involving them in mucus, or their being agglutinated to the surface of the matrix, only to be softened and diffused by rain. The spores in many species amongst the Melanconiei are remarkably fine; those of Stegonosporium have the endochrome partite and cellular. In Stilbospora and Coryneum the spores are multiseptate, large, and mostly coloured. In Asterosporium the spores are stellate, whilst in Pestalozzia they are septate, with a permanent peduncle, and crested above with two or three hyaline appendages.
Fig. 49.—Spore of Hendersonia polycystis. |
Fig. 50.—Spores of Dilophospora graminis. |
Fig. 51.—Spores of Discosia. |
Fig. 52.—Spore of Prosthemium betulinum. |
Fig. 53.—Spore of Stegonosporium cellulosum. |
Fig. 54.—Stylospores of Coryneum disciforme. |
Fig. 55.—Spores of Asterosporium Hoffmanni. |
Fig. 56.—Spores of Pestalozzia. |
Fig. 57.—Bispora monilioides. | |
The Torulacei externally, and to the naked eye, are very similar to the black moulds, and the mode of dissemination will be alike in both. The spores are chiefly compound, at first resembling septate threads, and at length breaking up into joints, each joint of which possesses the function of a spore. In some instances the threads are connate, side by side, as in Torula hysterioides, and in Speira, being concentrically arranged in laminæ in the latter genus. The structure in Sporochisma is very peculiar, the joints breaking up within an external tube or membrane. The spores in Sporidesmium appear to consist of irregular masses of cells, agglomerated into a kind of compound spore. Most of the species become pulverulent, and the spores are easily diffused through the air like an impalpable dust. They form a sort of link between the stylospores of one section of the Coniomycetes, and the pseudospores of the parasitical section.
Pseudospore is, perhaps, the most fitting name which can be applied to the so-called spores of the parasitical Coniomycetes. Their peculiar germination, and the production of reproductive bodies on the germ tubes, prove their analogy to some extent with the prothallus of other cryptogams, and necessitate the use of some term to distinguish them from such spores as are reproductive without the intervention of a promycelium. The differences between these pseudospores in the several genera are confined in some instances to their septation, in others to their mode of development. In the Æcidiacei the pseudospores are more or less globose, produced in chains within an external cellular peridium. In the Cæomacei they are simple, sometimes produced in chains, and sometimes free, with or without a caduceous peduncle. In the Ustilaginei they are simple, dark coloured, and occasionally attached in subglobose masses, as in Urocystis and Thecaphora, which, are more or less compact. In the Pucciniæi the distinctive features of the genera are based upon the more or less complex nature of the pseudospores, which are bilocular in Puccinia, trilocular in Triphragmium, multilocular in Phragmidium, &c. In the curious genus Podisoma the septate pseudospores are involved in a gelatinous element. The diffusion of these fruits is more or less complete according to their compact or pulverulent nature. In some species of Puccinia the sori are so compact that they remain attached to the leaves long after they are dead and fallen. In the genus Melampsora, the wedge-shaped winter-pseudospores are not perfected until after the dead leaves have for a long time remained and almost rotted on the ground. It is probable that their ultimate diffusion is only accomplished by the rotting and disintegration of the matrix. In the Cæomacei, Ustilaginei, and Æcidiacei the pseudospores are pulverulent, as in some species of Puccinia, and are easily diffused by the motion of the leaves in the wind, or the contact of passing bodies. Their diffusion in the atmosphere seems to be much less than in the case of the Hyphomycetes. By what means such a species as Puccinia malvacearum, which has very compact sori, has become within so short a period diffused over such a wide area, is a problem which in the present state of our knowledge must remain unsolved. It may be through minute and plentiful secondary spores.
| Fig. 58.—Pseudospores of Thecaphora hyalina. | Fig. 59.—Pseudospores of Puccinia. | Fig. 60.—Pseudospores of Triphragmium. |
| Fig. 61.—Pseudospores of Phragmidium bulbosum. | Fig. 62.—Melampsora salicina. (Winter fruit.) |
Spermatia are very minute delicate bodies found associated with many of the epiphyllous Coniomycetes, and it has been supposed are produced in conjunction with some of the Sphæriacei, but their real function is at present obscure, and the name is applied rather upon conjecture than knowledge. It is by no means improbable that spermatia do exist extensively amongst fungi, but we must wait in patience for the history of their relationship.
Trichospores might be applied better, perhaps, than conidia to the spores which are produced on the threads of the Hyphomycetes. Some of them are known to be the conidia of higher plants; but as this is by no means the case with all, it would be assuming too much to give the name of conidia to the whole. By whatever name they may be called, the spores of the Hyphomycetes are of quite a different type from any yet mentioned, approximating, perhaps, most closely to the basidiospores of the Hymenomycetes in some, and Gasteromycetes in others; as, for instance, in the Sepedoniei and the Trichodermacei. The form of the spores and their size differ materially, as well as the manner in which they are produced on the threads. In many they are very minute and profuse, but larger and less plentiful in the Dematiei than in the Mucedines. The spores of some species of Helminthosporium are large and multiseptate, calling to mind the spores of the Melanconiei. Others are very curious, being stellate in Triposporium, circinate in Helicoma and Helicocoryne, angular in Gonatosporium, and ciliate in Menispora ciliata. Some are produced singly and some in chains, and in some the threads are nearly obsolete. In Peronospora, it has been demonstrated that certain species produce minute zoospores from the so-called spores. The dissemination of the minute spores of the Mucedines through the air is undoubted; rain also certainly assists not only in the dispersion of the spores in this as in other groups, but also in the production of zoospores which require moisture for that purpose. The form of the threads, and the mode of attachment of the spores, is far more variable amongst the Mucedines than the form of the spores, but the latter are in all instances so slightly attached to their supports as to be dissevered by the least motion. This aids also in the diffusion of the spores through the atmosphere.
Fig. 63.—Spores of Helicocoryne.