Fungi: Their Nature and Uses

by M. C. Cooke

Finally, the spermogonia must be regarded as in some occult manner, which as yet has baffled detection, influencing the perfection of sporidia[P] In Rhytisma, found on the leaves of maple and willow, black pitchy spots at first appear, which contain within them a golden pulp, in which very slender corpuscles are mixed with an abundant mucilage. These corpuscles are the spermatia, which in Rhytisma acerinum are linear and short, in Rhytisma salicinum globose. When the spermatia are expelled, the stroma thickens for the production of asci and sporidia, which are afterwards developed during the autumn and winter.

Several of the species of Hysterium also possess spermogonia, notably H. Fraxini, which may be distinguished from the ascigerous perithecia with which they are associated by their smaller size and flask-like shape. From these the spermatia are expelled long before the maturity of the spores. In Hypoderma virgultorum, H. commune, and H. scirpinum, the spermogonia are small depressed black capsules, which contain an abundance of minute spermatia. These were formerly regarded as distinct species, under the name of Leptostroma. In Stictis ocellata a great number of the tubercles do not pass into the perfect state until after they have produced either linear, very short spermatia, or stylospores, the latter being reproductive bodies of an oblong shape, equal in size to the perfect sporidia. Some of the tubercles never pass beyond this stage.

Again, there is a very common fungus which forms black discoid spots on dead holly leaves, called Ceuthospora phacidioides, figured by Greville in his “Scottish Cryptogamic Flora,” which expels a profusion of minute stylospores; but later in the season, instead of these, we find the asci and sporidia of Phacidium ilicis, so that the two are forms and conditions the one of the other.

In Tympanis conspersa the spermogonia are much more commonly met with than the complete fruit. There is a great external resemblance in them to the ascigerous cups, but there is no evidence that they are ever transformed into such. The perfect sporidia are also very minute and numerous, being contained in asci borne in cups, which usually surround the spermogonia.

In several species of Dermatea the stylospores and spermatia co-exist, but they are disseminated before the appearance of the ascigerous receptacles, yet they are produced upon a common stroma not unlike that of Tubercularia.

In its early stage the common and well-known Bulgaria inquinans, which when mature looks like a black Peziza, is a little tubercle, the whole mass of which is divided into ramified lobes, the extremities of which become, towards the surface of the tubercle, receptacles from whence escape waves of spermatia which are colourless, or stylospores mixed with them which are larger and nearly black.

Amongst the Sphæriacei numerous instances might be cited of minute stylosporous bodies in consort with, or preceding, the ascigerous receptacles. A very familiar example may be found at the base of old nettle stems in what has been named Aposphæria acuta, but which truly are only the stylospores of the Sphæria coniformis, the perithecia of which flourish in company or in close proximity to them. Most of these bodies are so minute, delicate, and hyaline that the difficulties in the way of tracing them in their relations to the bodies with which they are associated are very great. Nevertheless there is strong presumption in favour of regarding some of them as performing the functions which the name applied to them indicates.

Professor de Bary cautiously refrains from accepting spermatia other than as doubtful or at least uncertain sexual bodies.[Q] He says that the Messrs. Tulasne have supposed that the spermogonia represented the male sex, and that the spermatia were analogous to spermatozoids. Their opinion depends on two plausible reasons,—the spermatia, in fact, do not germinate, and the development of the spermogonia generally precedes the appearance of the sporophorous organs, a double circumstance which reminds us of what is known of the spermatozoids and antheridia of other vegetables. It remained to discover which were the female organs which underwent fecundation from the spermatia.

Many organs placed at first amongst spermatia have been recognized by M. Tulasne as being themselves susceptible of germination, and consequently ought to take their place among legitimate spores. Then it must be considered that very many spores can only germinate under certain conditions. It is, therefore, for the present a doubtful question whether there exist really any spermatia incapable of germination, or if the default of germination of these corpuscles does not rather depend on the experiments hitherto attempted not having included the conditions required by the phenomena. Moreover, as yet no trace has been discovered of the female organs which are specially fecundated by the spermatia.

Finally, there exist in the Ascomycetes certain organs of reproduction, diverse spore-bearing apparatus, pycnidia, and others, which, like the spermogonia, usually precede ascophorous fruits. The real nature of the spermogonia and spermatia should therefore be regarded as, at present, very uncertain; as regards, however, the spermatia which have never been seen to germinate, perhaps it is as well not to absolutely reject the first opinion formed concerning them, or perhaps they might be thought to perform the part of androspores, attributing to that expression the meaning which Pringsheim gives it in the Conferoæ. The experiments performed with the spermatia which do not germinate, and with the spermogonia of the Uredines, do not, at any rate, appear to justify the reputed masculine or fecundative nature of these organs. The spermogonia constantly accompany or precede fruits of Æcidium, whence naturally follows the presumption that the first are in a sexual relation to the second. Still, when Tulasne cultivated Endophyllum sempervivum, he obtained on some perfectly isolated rosettes of Sempervivum some Æcidium richly provided with normal and fertile spores, without any trace of spermogonia or of spermatia.