It seems not easy to determine precisely, to the operation of what cause or causes the increase in the size of these circles from year to year should be attributed. Is it the projectile force with which the spores are disseminated all round, that has carried them so uniformly beyond the margin of the last ring as to form a concentric circle for the next of larger diameter beyond? Or is the cause to be sought underground, in the general spread of the spawn of last year in all directions outwards, but only fertile in a concentric ring beyond the site of the last crop, which had already exhausted the ground, and so rendered it incapable of supporting any new vegetable life? Or do both these causes conspire in this result? The quantity of spawn and of the spores necessarily contained in it, and the depth to which they penetrate under the surface of the soil, renders the possibility of their spreading in the latter way easily conceivable.[102]
ON THE DEVELOPMENT OF FUNGUSES.
“Ins Innre der Natur dringt kein erschaffner Geist,
Zu glücklich wem sie nur die äussre Schale lösst.”—Haller.
It would be an insult to the reader’s understanding, and a most idle waste of his time, to attempt to confute such self-destroying dogmas as those of “spontaneous” or of “equivocal” generation, which last is only a clumsy équivoque expressive of the same thing: we might just as well talk of the pendulum of a clock generating the time and space in which it librated, as of dead matter spontaneously quickening and actuating those new movements of which some of its particles have become the seat; for how, in the name of common sense, can that which we assume to be dead, i. e. emphatically and totally without life, convey such purely vital phenomena as those of intus-susception and growth, which by the very supposition are no longer within itself? Life, on such an hypothesis as this, ceases to be the opposite and antagonist principle to death, of which it then becomes but a different mode and a new phasis. It is not the incomprehensibility of such a notion (be it well understood) against which the objection lies, for as life begins and ends in mystery, that would be no objection; it lies in the rashness of attempting to solve an admitted mystery, by placing a palpable absurdity in its room; vainly and irreverently arrogating to itself the honours of a discovery which we are to believe if we can! At this rate, addled eggs, abandoned by the vital principle, might take to hatching themselves! A more legitimate and very interesting subject for inquiry is, whether those funguses which are parasitical (i. e. derive their support from the structures whence they emanate) are so many separate constituents of a superior life under analysis, or each of itself a new individual? In support of the first view, it is urged that since reproduction in such lower existences is nothing but a modification of nutrition, a new process might well originate from its perversion, and thus give rise to new products; and just as the change in the ordinary nutrition of our bodily organs is prone to give birth to various local disorganizations or morbid growths, such, it is argued, might be the origin of fungoid growth on trees. But then comes the difficulty: such a view does not, and plainly cannot, explain the development of the not parasitical kinds, of which the origin should be the same; no, nor even of all that live by suction at the expense of other plants, since there are as many kinds which quicken in dead and decaying structures, as there are that issue out of decrepit and living ones; here, then, it is plain that perverted nutrition can have nothing to do with their production, for in this case nutrition has, by the supposition, ceased; and to talk of disease after death would be a strange figure of speech indeed! An elm or oak is frequently dead five, seldom less than three, years before these parasitical growths make their appearance, from which it would appear to follow that seeds are not developed by, but that they must be extraneous to, and independent of, any pathological relation of the plant from which they grow. If then fungus life be not to be sought for, and cannot with propriety be said to originate in any morbid conditions of the tissues from which they spring, whence do they derive life—in other words, whence in every instance comes that particular seed which, when quickened, is to produce after its kind? Lies this dormant for a season in those dead and decaying tissues, which a little later the plant originating from it is destined to embellish; or is the living germ first brought to them by the winds, and merely deposited on their surface, as in a fitting nidus on which their future development is to be effected? Some writers take one view, some another. Many believe the seeds of funguses to come directly from the earth,[103] and to be drawn up with the sap, which, as it penetrates throughout the tissues of the plant, must carry the seeds also along with it. That such is actually sometimes the case is certain, since we can not only plant parasitical blights of a particular kind so as to infect particular plants, but may also by digging a trench between those that have already become diseased, and those that are still healthy, stay the progress of the blight—thus clearly establishing not only the fact of seeds, but also the highly interesting additional one, of their ascent into the structures of plants by intus-susception; and to arrive at a general view from these particular cases, this would seem to be the usual mode of their propagation. Neither does it make against this view nor is it more in favour of the other, which supposes the germs to be derived primarily from the air, and to be thence precipitated on the structures where they grow, that funguses are found on organizations in decay, on withered boughs, and on seared leaves, out of which all sap must of course have been long ago exsiccated; for what then? though the sap does, the seeds do not, evaporate with it. These, once absorbed and diffused during the lifetime of the plant throughout its whole economy, remain there in a state of potential activity, ready to burst forth and germinate whenever the necessary conditions for these wonderful changes shall be presented to them, just as though the seeds of corn now flourishing in different parts of England, had first existed for some thousand years as mummy wheat, potentially and unquickened. Nothing perishes in nature: “destructio unius matrix alterius;” life may change titles, but never becomes extinct; so soon as the more perfect plant dies, a host of other vegetable existences, hitherto enthralled by laws of an organization superior to their own, now that the connection has been dissevered, put forth their separate energies, and severally assert their independence. The poplar may have perished, root, stem, and branch, but its extinction is only the signal for other existences, which had been heretofore bound up and hid within its own, to assert themselves; and accordingly a Polyporus sprouts out here; here a Thelephora embellishes the dead bark; and here an Agaric springs out of the decaying fibres of its head: these in turn also decay, but as they moulder away they languish into a new kind of fungous life, of an inferior type to the last, as if their own vitality were inferior in kind to that of the decayed poplar, whence they lately issued.[104] Thus, since the seeds of funguses actually exist in great quantity in other plants, and since they occur in the closed interior of fruits and in corollas which are still in their envelopes (in either case out of the reach of the external air); since finally, the Pietra funghaia, which produces a Polyporus unknown to England, may be, notwithstanding, made to germinate in England by furnishing the stone with adequate supplies of water and of heat, that seems the more tenable hypothesis of the two, which, in every case, supposes the nidus of the fungus to furnish the seed, and the atmosphere, the conditions necessary for its quickening. How the seed is first made to quicken is another and most interesting question, still evolved in mystery. As there is no ocular evidence to be obtained of the usual organs of sex, some mycologists have separated funguses from the family of the clandestinely married Cryptogamia, to place them with the Agamia, which repudiate the marriage tie;[105] but as every argument from ignorance is unsafe, (and such would appear to be particularly the case here, when we consider how many things undoubtedly exist, which the imperfection of lenses and the circumscribed power of the eye prevent our seeing,) we should rather make use of what is displayed to us in the economy of other plants, in the way of analogy as applied to these, than deny what is likely, merely because it is not an object of sense. It would appear then, from what has been stated, that certain funguses are produced like other plants, from seeds; and more likely at least, in the parasitic kinds, that such seeds are derived by the plant which supports them from the ground, than deposited from the atmosphere. Before we proceed to the description of species, a few more words remain to be said about these spores, and a brief notice to be taken of those parts that are essential to all, and more especially of such as are characteristic of those higher forms of funguses which are the more immediate subject of the present work.
SPORES OR SEEDS.
All funguses have not seeds,—at least, seeds apparent to us;[106] but if we reflect that these, even where visible, can do no more than present to our senses the visible tabernacle of that life which is still invisible, and which, not being material, must ever elude our search,[107] then it will not appear so difficult to conceive that the apparently seedless threads of some particular moulds should include, in their interior, vital germs of some sort, which, being homogeneous with, or of the same colour as, the parenchyma of the mould itself, are invisible—just as we know them to be for a season in puff-balls, in the veins of truffles, or in the Agyrium, the receptacle of which last breaks up, when ripe, into sporidia, which then and not till then become manifest. The seeds of funguses are called spores: in the great majority of cases, the microscope, which brings their shapes under observation (for to the naked eye they appear as dust), presents them to us as round, oval, oblong, or even angular corpuscules, and, more rarely still, echinulate or with a tail. They are as various in size as in shape, the first bearing no proportion whatever to the dimensions of the future plant. They vary, too, greatly in colour, being sometimes of a pure white, and continuing so throughout the whole of their seminal existence; at other times, the white acquires a yellow tinge on drying. Some are brown, some yellow, some pink, some purple, some purple-black, and some pass successively from pink to purple, and from purple to purple-black.[108] These seeds or spores are sometimes naked, but are much more commonly shut up in little pouches or receptacles, either of a regular or of an irregular shape; the first are called thecæ, the latter sporanges; thecæ (which are in shape similar to the cases of the same name that used to receive the ancient εἱλίγματα, or scrolls) are small, cylindrical bodies, in which the seeds lie one over the other, as in a rouleau; they are themselves let into a receptacle (or that part of the fungus the office of which is to receive and support the reproductive organs) in a regular and symmetrical manner, and at length occupy it completely. Not all are prolific; for some, pressing upon others, cause them to abort, leaving wherever this happens, sterile thecæ, or paraphyses, between those that are fertile. Sporanges are little globose or turbinated receptacles, frequently furnished with a pedicle, in which the seeds lie without order, as they are themselves inserted symmetrically, or without order, into the receptacle. Sometimes these seeds are packed in series of fours, as in the fimetary Agarics; in other genera, as in the Helvellæ and Morels, they are stored away in series of eights. The spores, so soon as they are ripe, either drop out of the sporiferous membrane (hymenium), or, as more frequently happens, are projected from it with an elastic jerk, or else, as is the case of Agarics of a deliquescent kind, return to the earth mixed up with the black liquid into which these ultimately resolve themselves. Sometimes the whole external surface of the fungus is dusted with seed; but much more frequently they are restricted to some particular part, and either lie on the upper side, as in the Pezizæ, or on that which is beneath, as in the mushroom. The spores generally lie on the outside of the fungus, but in the puff-ball, as every one knows, they are internal, and in such prodigious quantity as sometimes entirely to fill its cavity. It is a speculation from Germany, that spores are capable of altering their forms, and that according to the accidents of climate or soil, they assume this or that type, and give rise at different times to different kinds of funguses; on which it is sufficient to remark, that while there is not the least foundation for such an hypothesis, there is in fact much evidence against it; nature acts by immutable laws and has no changelings. To appeal to experience, when did mushrooms ever spawn toadstools? When was the Pietra funghaia ever seen to bring forth anything but its own Polyporus? or the fig, the poplar, or the hazel (when singed and watered to render them prolific) exhibit any but their own particular mushroom? Spores are endowed, like other seeds, with an extraordinary vitality, which may lie dormant in them for an indefinite period; but unlike most other seeds, they seem capable of resisting the prolonged heat of boiling water, infused in which, and poured upon the ground, they are still capable of producing each after its kind. The specific gravity of spores is greater than that of water, as may be seen by placing a mushroom over a glass which contains it, when, falling upon the surface, they presently subside to the bottom. These spores sometimes merely multiply without any further progress in development; sometimes they proceed a certain way only, and then, the conditions necessary for their further advance failing, this is arrested; sometimes, as in the Sistotrema, the plant appears twice under a perfect form, being for part of its existence a Hydnum, and during the other half a Boletus; but, generally speaking, these minute corpuscular bodies are destined to receive an infinite variety of protean and imperfect forms, and to pass stage by stage, and step by step, to the full attainment of that ultimate one which they assume when their growth has reached its natural limits. Sometimes the spore expands outright into a puff-ball; sometimes it shoots up straight into a club, as in some of the Clavarias; or lies like a bowl, resupinate on the ground and stalkless, as in the Peziza; in other cases, it assumes the more perfect but much less simple forms of Chanterelle, Boletus, Dædalea, Morel, or Mushroom.
DEVELOPMENT OF SEEDS.
The mode in which the organs immediately containing the seeds are formed, differs according to the family. In the tribe of puff-balls, where the seed is formed in the interior of the fungus, there is no hymenium; a few of the internal cells (when the Lycoperdon has attained its full size) begin to enlarge, and these in a short time are found to contain small granules, generally of a determinate number, and moistened by a fluid secreted from within the walls. In such funguses as have an hymenium it is only some of the superficial cells, and these in a particular position in reference to the receptacle, that contain seeds; though perfect identity of structure throughout, is evinced in a conclusive manner if we invert the head of a young fungus on its stalk; for then these thecæ begin to form and to fill themselves with seed, not on the side where they were about to do so previous to this inversion of the head, but on that which was the uppermost and sterile surface, and which, now that it is the undermost, has become prolific. The expansion of a fungus, according to Vittadini, is effected as follows:—“These thecæ,” of which we have been speaking, “as they swell, become distended with the contained seed, and mostly so at their free extremity, since they have more room for expansion in that direction than at the other, which is impacted into the substance of the pileus; in consequence of this, a series of wedges are formed which, as the seed continues to distend them, force out the pileus, loosen its marginal connections with the stalk, uncurl its involuted borders, and finally open up its cells, pores, and sinuses.”[109]