In the genus Endophyllum, as its name implies, the peridium is imbedded within the substance of the succulent leaves. The only species we possess is found rarely upon the common house-leek.
We have derived much pleasure in viewing the astonishment and delight exhibited by friends to whom we have personally communicated specimens of the little fungi we have enumerated for examination under the microscope; and we recommend with confidence this group of parasitic plants, unfortunately so little known, as well worthy of the attention of all who are interested in the minute aspects of nature, and who can recognize the hand—
“That sets a sun amidst the firmament,
Or moulds a dew-drop, and lights up its gem.”
CHAPTER II.
SPERMOGONES.
IN addition to their spore-bearing spots, lichens have for some time been known to possess other organs, termed spermogones, which are probably concerned more or less in the reproductive process. The first intimation of the existence of similar bodies in the entophytal fungi originated with M. Unger in 1833, but it was left to Dr. de Bary and the Messrs. Tulasne, twenty years later, to examine and determine satisfactorily the nature and value of the spermogones of the Uredines. It was at first believed that the smaller pustules—which sometimes precede, and sometimes accompany, the cluster-cups and some other allied fungi—were distinct species developed simultaneously therewith, or members of a new genus, which, under the name of Æcidiolum exanthematum, found a place in the mycologic system.
Without staying to trace the stages through which the elucidation of their true nature proceeded, it will suffice for our purpose to tell what is now known of these secondary organs; to accomplish which we must stand greatly indebted to the independent researches of Messrs. de Bary and Tulasne. It has been demonstrated that both these bodies, namely, the primary organs or cluster-cups, and the secondary organs or spermogones, are developed from the same mycelium; but the value of the latter is still undetermined. If they possess any fecundative power, the process has not been traced; or if they are in themselves reproductive, they have not at present been seen to germinate. Their uses, therefore, in the economy of the parasitic plant of which they are now known to form a part is still a mystery, and they remain valueless in the determination of genera and species. Any speculation which might regard them as male organs would be premature, and without support in fact. Hitherto only some species of the genera described in the foregoing chapter, and others belonging to genera not hitherto named, have been ascertained to possess spermogones. Of the former are the Rœsteliæ, some species of Æcidium, as those of Euphorbia, &c., and Peridermium Pini.
These spermogones are of a very simple structure—very delicate, indeed; so much so, that they will scarcely bear preparation for demonstration. De Bary states that they originate from plain, delicate, inarticulate threads, about half the thickness of the mycelium (the root-like branching fibres which form the fundamental stratum of fungoid growths), which are developed in large quantities, and closely packed together. These threads are compacted together so as to form an outer enveloping integument or peridium, which is either globular or hemispherical (or in some instances elongated), more or less immersed, and at length opening at the apex (fig. 153) by a regularly formed minute ostiolum. The inner wall of the peridium is covered with a thick forest of simple filaments standing on end. From the summit of these filaments or sterigmata, the spermatia are borne. These are either isolated or associated together in strings or chaplets, are exceedingly minute, of an ovoid or oblong shape, and are produced in such numbers as to fill the cavity of the spermogone. Besides these, a viscid fluid is secreted, in which the spermatia are immersed, and which is expelled with them from the orifice of the peridium. According to the density of this fluid, or the hygrometric state of the atmosphere, it appears sometimes in drops, and sometimes oozing out in threads or cirrhi from the spermogones. To compare minute things with gigantic, as a recent author has observed, it resembles the lava issuing from the crater of a volcano. The colour of this spermatiferous matter is commonly orange, but in some instances brown, though not constantly of the same colour as the spores produced from the same mycelium. This gelatinous substance is dissolved away from the granular bodies which are immersed in it, by adding a little water upon the slide on which the mass is placed for examination. The granules, or spermatia, then exhibit those peculiar movements which have been observed in the similar bodies in lichens, and fitly described as “a sort of oscillating motion, as of a body attached at one extremity.” The cause of this motion is at present uncertain, vibratile ciliæ, to which similar movements are referred, being altogether absent; but probably, as De Bary believes, the cause may be found in the influence of exosmose.
The largest spermatia yet examined (those of Peridermium Pini) have a length equal to 1/2500 of an inch, but their width seldom exceeds 1/100000 of an inch, whilst in others their length does not exceed the width of those just named.