Soft and yielding as vegetable structures appear to the touch, the expansive force of their growth is almost beyond calculation. The effects of this power, of which the experience of every one will furnish him with some instances, are perhaps nowhere more strikingly exemplified than amidst the ruins of its own creation. Coeval with many old brick fabrics of earlier times, perhaps embedded in the very mortar which holds them together, it may lurk there for centuries in quiescence, till once arousing its energies, it continues to exert them in ceaseless activity ever after. It has at Rome planted its pink Valerians on her highest towers, and its wild fig-tree in the breaches of her walls; nor are the granite obelisks of her piazzas, nor the classic groups in marble on her Quirinal mount, entirely exempt from its encroachments. A conspiracy of plants, one hundred strong, have long ago planned the destruction of the Coliseum; their undermining process advances each year, and neither iron nor new brickwork can arrest it long. That old Roman cement, which the barbarians gave up as impracticable, and the pickaxe of the Barberini had but begun to disintegrate, will, ere the lapse of another century, be effectually pulled to pieces by the rending arm of vegetation. Here, as erst in Juvenal’s time, the mala ficus finds no walls too strong to rive asunder, no tower beyond the reach of its scaling, no monument too sacred for it to touch. In the class of plants immediately under consideration, while the expansive effort of growth is equal to what it is in other cases, its effects are far more startling from their suddenness. M. Bulliard (to cite one or two instances out of a great many) relates, that on placing a Phallus impudicus within a glass vessel, the plant expanded so rapidly as to shiver its sides with an explosive detonation as loud as that of a pistol. Dr. Carpenter, in his ‘Elements of Physiology,’ mentions that “in the neighbourhood of Basingstoke a paving-stone, measuring twenty-one inches square, and weighing eighty-three pounds, was completely raised an inch and a half out of its bed by a mass of toadstools, of from six to seven inches in diameter, and that nearly the whole pavement of the town suffered displacement from the same cause.” A friend has seen a crop of puff-balls raise large flagstones considerably above the plane of their original level; and I have myself recently witnessed an extensive displacement of the pegs of a wooden pavement which had been driven nine inches into the ground, but were heaved up irregularly, in several places, by small bouquets of Agarics, growing from below.
REPRODUCTIVE POWER.
Funguses have a remarkable power of re-forming such parts of their substance as have been accidentally or otherwise removed. Vittadini found that when the tubes of a Boletus were cut out from a growing plant, they were after a time reproduced. Where deep holes have been eaten into these plants by snails, such holes, on the Boletus attaining to its full growth, are partially refilled. If the tender Polyporus be cut across, the wound immediately sets about healing by the first intention, leaving not even a cicatrice to mark the original seat of the injury. The Lycoperdons (Bovista), which are often accidentally wounded by the scythe, have the same faculty of repairing the injury, remodelling afresh the parts that may have been excised from them.[39]
MOTION.
In a recent work on ‘Insect Life,’ I have discoursed somewhat at large on the insufficiency of any kind of movements as proofs of sensation, quoting, amidst other evidences to this effect, certain remarkable movements in plants. Some of the present family exhibit the phenomena of insensitive motion in a remarkable manner, and might have been added to the list already cited in that publication. Mr. Robson has given us a very interesting account of the movements he observed in the scarlet Clathrus, which is here transcribed in his own words. It is interesting to notice how an unbiassed observer uses the very terms to designate the movements of a plant which would have been minutely descriptive of those of an insect:—“At first I was much surprised to see a part of the fibres, that had got through a rupture in the top of the Clathrus, moving like the legs of a fly when laid on his back. I then touched it with the point of a pin, and was still more surprised when I saw it present the appearance of a little bundle of worms entangled together, the fibres being all alive. I next took the little bundle of fibres quite out, and the animal motion was then so strong as to turn the head halfway round, first one way and then another, and two or three times it got out of the focus. Almost every fibre had a different motion; some of them twined round one another, and then untwined again, whilst others were bending, extending, coiling, waving, etc. The fibres had many little balls adhering to their sides, which I take to be the seeds, and I observed many of them to be disengaged at every motion of the fibres; the seeds appeared like gunpowder finely granulated.” Instances from other authors abound. “An Helvella inflata, on being touched by me once, threw up its seeds in the form of a smoke, which arose with an elastic bound, glittering in the sunshine like particles of silver.”[40] “The Vibrissea truncorum, taken from water and exposed to the rays of the sun, though at first smooth, is soon covered with white geniculated filaments, which start from the hymenium, and have an oscillating motion.”[41] The Pilobolus, of which so accurate an account has been given us by the great Florentine mycologist,[42] casts, as its name imports, its seeds into the air; these also escape with a strong projectile force from the upper surface of Pezizas, the anfractuosities of the Morel, and from the gills of Agarics.[43]
PHOSPHORESCENCE.
Several kinds of funguses, and the spawn of the truffle, emit a phosphorescent light; of the first, the Agaricus olearius, not uncommon in Italy, is sometimes seen at night, feebly shining amidst the darkness of the olive grove. The coal-mines near Dresden have long been celebrated for the production of funguses which emit a light similar to a pale moonlight. Mr. Drummond describes an Australian fungus with similar properties; and another very interesting one, an Agaric, is noticed by Mr. Gardner, in his ‘Travels in Brazil.’[44]
DIMENSIONS.
Most funguses do not present great anomalies in their size, but retain nearly the same dimensions throughout the whole course of their being; some few species, however, seem to have a faculty of almost indefinite expansion. The usual size of a puff-ball, as we all know, is not much larger than an egg, but some puff-balls attain to the dimensions of the human head,[45] or exceed it. Mr. Berkeley quotes the case of a Polyporus squamosus, which in three weeks grew to seven feet five inches in periphery, and weighed thirty-four pounds; also of a Polyporus fraxineus, which in a few years measured forty-two inches across. Clusius[46] tells us of a fungus in Pannonia, of such immense size, that after satisfying the cravings of a large mycophilous household, enough of it remained to fill a chariot; this must have been the Polyporus frondosus, to which Polyporus John Bapt. Porta[47] also alludes as that called gallinace[48] by the Neapolitans, which is so big, he says, that you can scarcely make your hands meet round it, “brachiis diductis vix homo complecti possit;” he had known it attain twelve pounds weight in a few days.[49] Bolton, in 1787, found an Agaricus muscarius, which, “after the removal of a considerable portion of its stalk, weighed nearly two pounds;” Withering, an A. Georgii, “which weighed fourteen pounds,” and Mr. Stackhouse another of the same species in Cornwall, “which was eighteen inches across, and had a stem as thick as a man’s wrist;” and I lately picked in the park at Buckhurst, a Boletus edulis which measured twenty-eight inches round its pileus, and eight round the stem, and a few days later a B. pachypus, the girth of which was thirty-two inches.