CHAPTER XVII.

VEGETABLE LAMPS.

One of the most remarkable and awe-inspiring phenomena of the ocean is the water-spout,--a lofty column composed of tons of water, whirling upward, lifted by the mighty force of the wind. From a distance the formation of a spout is an interesting sight. In my own observations, there has generally been a low-lying bank of dark lead-colored cloud to announce its coming. From this a sharp cone, seemingly of cloud, was seen to drop, and in a very few moments an attenuated pillar rose from the water directly beneath it. The two appeared to meet, and, the alliance consummated, the lofty column moved away with a greater or less velocity.

Near proximity to them is not unaccompanied with danger; and I once found myself in the centre of four or five, which were moving slowly about. The wind almost entirely died away, so that had our boat been a large one, we would have been completely at the mercy of the aqueous giants; as it was, we lowered the sail, and taking the oars, succeeded in avoiding them all.

It is the general impression, that if a water-spout touches an object, or is struck, its form is broken, and the water descends; but this is not always the case. I was standing one day upon the sea-wall of Fort Jefferson, on the island of Tortugas, Florida reef, when I perceived a lofty water-spout, a mile to the east, headed directly for the fort, as I thought. In a few moments it struck Long Key, a narrow island a quarter of a mile away; passing over perhaps one hundred and fifty feet of it, striking a small schooner which had been hauled upon the beach, twisting it around, and then continuing its course with great rapidity. It now turned a little to the north; and, seeing that in all probability it would not strike the fort, I awaited its coming. Never shall I forget the awful grandeur of the sight, as the watery monster, seemingly several thousand feet in height, reached the shoal. For some reason which I cannot explain, the central portion was invisible, but the upper part was distinctly seen, and appeared to be nearly over my head; and its proximity may be imagined from the fact that the drops from it seemed like a heavy rain. The entire spout was bent like a bow by the wind, and was moving along with great rapidity. I could not keep up with it, though running at utmost speed as it passed. Its progress was accompanied by a loud roar, and a hissing, splashing sound, while great masses of foam were thrown up before and behind. In its wake followed numbers of gulls, feeding upon the small fishes killed by the rush of waters; and where it crossed the shoal, in perhaps eight feet of water, quite a trench was scooped out. Imagine such a column at night coursing over the ocean; its entire shape outlined against the darkness in phosphorescent light (Plate XXV.), and an idea may be gained of the magnificent spectacles which, on rare occasions, are produced by some of the simplest of plants,--the diatoms,[45] whose nuclei are luminous.

The southern oceans, in certain places, often swarm with these minute light-givers, and when borne aloft in the spout, they tend to produce one of the most remarkable and striking scenes possible to imagine. In color these luminous columns are yellow, of different shades, according to the numbers of diatoms present. The naturalists of the “Challenger” found that _P. pseudo-noctiluca_ was always present, and often existed at the surface in vast numbers, in the tropics and subtropical regions where the temperature was over sixty-eight or seventy degrees; and the most beautiful exhibitions seen during the cruise were due to these little forms. They have been observed in the Bay of Funchal all the year round. The light was equally brilliant in each species; and in each, when disturbed several times in succession, the phosphorescence perceptibly diminished, and finally disappeared: but after an hour’s rest, it re-appeared as brilliant as before.

The phosphorescence of plants, though not so remarkable in its general manifestations as in the forms previously reviewed, is sufficiently interesting to attract general attention. In nearly all countries these vegetable lamps are found; and even in the old legends of the Greeks, Hindus, and Persians, references to the “burning bush,” and other luminous phenomena are met with, evidently having some foundation in fact. In India the old natives tell the story, that their forefathers, who visited the mountain of Sufed Koh, at the north of Nalroo in Afghanistan, found a spring in which grew a bush which, from a distance, seemed to emit a brilliant light; but if any one approached, it immediately disappeared, vanishing in the air. In 1845 the white residents of Simla were informed by the natives that a wonderful plant was illuminating the mountains near Syree; and those who investigated it expressed the belief that the light, if it existed at all, came from a species of _Dictamnus_, which was known to grow about Gungotree and Jumnotree.

Even in Josephus we find reference to the luminosity of plants. “There is a certain place,” he says, “called Baaras, which produces a root of the same name with itself; its color is like to that of flame, and towards evening it sends out a certain ray like lightning; it is not easily taken by such as would do it, but recedes from their hands.”

In the “Proceedings of the Royal Asiatic Society” of April, 1845, there is reference to a luminous root-stock found in the Oraghum jungles, “gleaming in the dark with all the vividness of a glow-worm, or the electric scolopendra, after having been moistened with a wet cloth applied to its surface for an hour or two, and did not seem to lose the property by use, becoming lustreless when dry, and lighting up again whenever moistened.” It is probable that this is the plant which is referred to by the Brahmins as _Jyotismati_, produced, it is said, by a variety of _Cardiospermum_. According to Sanscrit authorities, it abounds in the Himalaya Mountains; and is well known, according to Major Madden, at Almora, where investigation showed it to be, at least in this locality, the roots of the fragrant khus-khus grass, which at certain times, as rainy nights, was luminous.

In South America and Asia occurs a plant known to science as _Euphorbia phosphorea_; which emits, when severed or cut, a milky juice somewhat resembling that of the dandelion. At night the juice of the former is, when heated, brilliantly phosphorescent; so much so, that, according to M. Martins of Montpellier, if the stem be broken and used as a pen, this _latex_ may be employed as a luminous ink, the characters appearing in the dark as letters of fire. One of the most familiar exhibitions of vegetable luminosity is seen in the “touchwood” or “fox-fire,” which many a schoolboy has employed in the perpetuation of a practical joke. It is found about old decayed trees, and is simply rotten wood permeated by the mycelium of fungi, which is luminous in the dark. This simple luminant is often quite sufficient to enable one to read large print, and is often the cause of laughable episodes among camping-parties. A friend of the writer, in building a camp-fire in the deep woods, hauled an old log to the door of the tent, and there broke it up, making a fire about which the men slept. In the night, after the fire was extinguished, one of the party awoke, and with a shout aroused the rest, who sprang to their feet, believing that they were lying among coals; as all about were masses of wood seemingly at a white heat, but which investigation showed to be fox-fire.

This luminous decayed wood often rolls out from trees in the forests, to the astonishment or alarm of animals unfamiliar with fire.

Perhaps the most remarkable exhibition of fox-fire is recorded by the Rev. M. J. Berkeley, who says, “A quantity of wood had been purchased in a neighboring parish, which was dragged up a very steep hill to its destination. Amongst them was a log of larch or spruce, it is not quite certain which, twenty-four feet long, and a foot in diameter. Some young friends happened to pass up the hill at night, and were surprised to find the road scattered with luminous patches, which, when more closely examined, proved to be portions of bark or little fragments of wood. Following the track, they came to a blaze of white light which was perfectly surprising; on examination it appeared that the whole of the inside of the bark of the log was covered with a white byssoid mycelium of a peculiarly strong smell, but unfortunately in such a state that the perfect form could not be ascertained. This was luminous; but the light was by no means so bright as in those parts of the wood where the spawn had penetrated more deeply, and where it was so intense that the roughest treatment scarcely seemed to check it. If any attempt was made to rub off the luminous matter, it only shone the more brightly; and when wrapped up in five folds of paper the light penetrated through all the folds on either side as brightly as if the specimen was exposed; when, again, the specimens were placed in the pocket, the pocket when opened was a mass of light. The luminosity had now been going on for three days. Unfortunately we did not see it ourselves till the third day, when it had, possibly from a change in the state of electricity, been somewhat impaired; but it was still most interesting, and we have merely recorded what we saw ourselves. It was almost possible to read the time on the face of a watch, even in its less luminous condition. We do not for a moment suppose that the mycelium is essentially luminous, but are rather inclined to believe that a peculiar occurrence of climatic conditions is necessary for the production of the phenomenon, which is certainly one of great rarity. Observers as we have been of fungi in their native haunts for fifty years, it has never fallen to our lot to witness a similar case before; though Professor Churchill Babington once sent us specimens of luminous wood, which had, however, lost their luminosity before they arrived. It should be observed that the parts of the wood which were most luminous were not only deeply penetrated by the more delicate parts of the mycelium, but were those which were most decomposed. It is probable, therefore, that this fact is an element in the case as well as the presence of fungoid matter.”

[Illustration:

PLATE XXII.

LUMINOUS FISH.

(_Malacosteus niger._)

With two luminous disks, one emitting a golden, the other a greenish light.]

Any one who has wandered among old tree-trunks in search of insects, or been a careful observer in underground nooks and corners, must have seen the white tangles, often of beautiful shape, which constitute the forms of some fungi. They are frequently to be seen under old boards in frost-like designs of great delicacy, and many of these are supposed by some to have a certain relation to luminous woods. Around old tree-stumps, the decayed arms of the oak especially, long, cylindrical, flexible branches with a hard bark covering are often found. When freshly broken, the interior is pure white, later changing to a more or less deep brown tint. The white, flocculent extremities form the mycelium of the fungus known as _Rhizomorpha subterranea_, one of the most interesting of the luminous plants. Its mystic light is often seen in caves, where the rootlets have made their way, gleaming with a soft phosphorescence.

In coal-mines this plant is quite common, and has been especially observed near Dresden. Ehrman speaks in enthusiastic terms of these “vegetable glow-worms,” as he calls them, which he observed gleaming on the walls and in the crevices of Swedish mines.

In Bohemia the caves are not uncommonly illumined by this interesting cryptogam; and, according to Phipson, sufficient light has been emitted in English coal-mines from this source to enable miners to read ordinary print. In the mines of North Hesse, Germany, the conditions are particularly favorable for such displays, the gleams being described as resembling moonbeams stealing through the gloomy caverns.

That this fungus is luminous when detached, is shown by the following from M. Tulasue, in the “Annals of Natural Science,” 1848. “On the evening of the day I received the specimens,” he writes, “the temperature being about 22° C., all the young branches brightened with an uniform phosphoric light the whole of their length. It was the same with the surface of some of the older branches, the greater number of which were still brilliant in some parts, and only on their surface. I split and lacerated many of these twigs, but their internal substance remained dull. The next evening, on the contrary, this substance, having been exposed to contact with the air, exhibited at its surface the same brightness as the bark of the branches. Prolonged friction of the luminous surfaces reduced the brightness, and dried them to a certain degree, but did not leave on the fingers any phosphorescent matter.” And again, “By preserving these _Rhizomorphæ_ in an adequate state of humidity, I have been able for many evenings to renew the examination of their phosphorescence; the commencement of desiccation, long before they really perish, deprives them of the faculty of giving light.”

Rumphius, the celebrated botanist, was perhaps the first European to discover the phosphorescence of fungi, observing it in a large specimen on the island of Amboine, which he named _Fungus igneus_, or fire-mushroom. In America such exhibitions are rare. Mr. H. K. Morrell, editor of “The Gardiner (Me.) Home Journal,” informed me some few years ago that he had observed the phosphorescence of _Tianus stypticus_ in his garden; the young of which, being especially brilliant, emitted a steady light. In Brazil a certain agaric is famous for its vivid luminosity. It was observed by Mr. Gardner in 1840, who says, referring to the species which has been named _Agaricus gardneri_, “One dark night about the beginning of December, while passing along the streets of the Villa de Natividate, Goyaz, Brazil, I observed some boys amusing themselves with some luminous object, which I at first supposed to be a kind of large fire-fly; but, on making inquiry, I found it to be a beautiful phosphorescent species of _Agaricus_, and was told that it grew abundantly in the neighborhood on the decaying fronds of a dwarf palm. The whole plant gives out at night a bright phosphorescent light, somewhat similar to that emitted by the larger fire-flies, having a pale greenish hue. From this circumstance, and from growing on a palm, it is called by the inhabitants ‘Flor de Coco.’”

Dr. Cuthbert Collingwood had a similar experience with an allied species in Borneo. “The night being dark, the fungi could be very distinctly seen, though not at any great distance, shining with a soft, pale greenish light. Here and there spots of much more intense light were visible, and these proved to be very young and minute specimens. The older specimens may more properly be described as possessing a greenish, luminous glow like the glow of the electric discharge; which, however, was quite sufficient to define its shape, and when closely examined, the chief details of its form and appearance. The luminosity did not impart itself to the hand, and did not appear to be affected by the separation from the root on which it grew, at least not for some hours. I think it probable that the mycelium of this fungus is also luminous; for, upon turning up the ground in search of small, luminous worms, minute spots of light were observed, which could not be referred to any particular object or body, when brought to the light and examined, and were probably due to some minute portions of its mycelium.” Mr. Hugh Low has stated that “he saw the jungle all in a blaze of light, by which he could see to read, as some years ago he was riding across the island by the jungle road, and that this luminosity was produced by an agaric.”

Australia has produced a number of luminous toadstools. Drummond found some striking forms near Swan River. He had noticed two species growing as parasites on the stumps of trees. Their appearance in the daytime did not attract particular attention; but at night they developed into veritable plant lamps, exceeding any thing that he had ever seen. One was about two inches across, and grew in clusters on the stump of a banksia-tree which was surrounded by water. When the little plant was secured from its miniature island home, it could have been used as a lamp for several successive nights, a newspaper being read by placing the agaric on it, the light illuminating the type in the immediate vicinity. As the plant dried, the light gradually diminished.

[Illustration:

PLATE XIII.

LUMINOUS MUSHROOMS.

LUMINOUS INSECT. (_Geophilus electricus._)]

Later Mr. Drummond found a giant specimen that was sixteen inches in diameter and a foot high, a veritable chandelier. He says regarding it, “This specimen was hung up inside the chimney of our sitting-room to dry; and, on passing through the apartment in the dark, I observed the fungus giving out a most remarkable light, similar to that described above. No light is so white as this, at least none that I have ever seen. The luminous property continued, though gradually diminishing, for four or five nights, when it ceased on the plant becoming dry. We called some of the natives, and showed them this fungus when emitting light. The room was dark, for the fire was very low and the candles extinguished; and the poor creatures cried out, ‘Chinga,’ their name for a spirit, and seemed afraid of it.”

A very attractive agaric, _Agaricus olearius_ (Plate XIII.), is found at the foot of olive-trees in Southern Europe. During the daytime the color is yellow, but observed at night it emits a brilliant blue light. Like the Australian species, it continues to emit light after it has been taken from the ground, the phosphorescence persisting for successive nights. So brilliant are the gleams, that they may be perceived at times before darkness sets in. Experiment showed that the light was extinguished when the temperature was below +90° to +6° C.; but the luminosity was not destroyed, as it re-appeared when the temperature was raised above this point. If kept some time in a temperature below freezing, it loses its light-emitting property entirely. It gleams as brightly under water as out; pure oxygen seems to have no effect upon it, and the most careful experiments fail to show the slightest elevation of temperature about the parts which shine. The light seems to emanate from the head (_pileus_) of the fungus, the _lamellæ_ of the latter, where the seeds are found, being the centre of the luminous phenomenon.

These interesting light-givers are perhaps more common than we are aware of, from the fact that nocturnal investigations in the woods are not frequent, nearly all the discoveries being the result of accident. A small, luminous fungus has been observed in the Andaman Islands. Gandichand found one in Manilla, while Dr. Hooker, as we have seen, refers to the presence of one in the Sikkim Himalayas.

These curious families of fungi are not only ornamental, but useful. In European countries the common mushroom[46] enjoys the widest popularity as an esculent, especially the cultivated varieties. The meadow mushroom is scarcely inferior, though stronger in flavor, and is preferred by many to the cultivated species. In France the champignon is largely eaten; and in Austria a kind which has no admirers in England finds a constant place in the markets during the summer. Truffles and morels are favorites not only in Europe, but also in the vales of Cashmere, where two or three species of morels are dried for consumption throughout the year. The great puff-ball is increasing in reputation as a breakfast delicacy in Great Britain, while the chantarelle and the hedgehog fungus are esteemed by many.

Numerous other species are more or less eaten by mycophagists, although they are never found in the public markets. A species of _Boletus_, cut in slices and dried, may be purchased throughout the year in most of the Continental cities. In Tahiti the Jew’s ear[47] is dried in large quantities and exported to China; while a species of agaric comes into the markets of Singapore, and another dried agaric is sent from the Cabul hills and the plains of north-western India. Several species of _Cyttaria_ are eaten in the southern parts of South America, and in Australia a native kind[48] is a favorite article of food. Indeed, a very long catalogue might be made of the species which are more or less consumed in different parts of the world.

The cultivation of fungi for esculent purposes has not hitherto been successful with any other species than the ordinary mushroom. Attempts were made in France to cultivate truffles, at first apparently with considerable promise, but ultimately without much satisfaction. There is no good reason to suppose it impossible or improbable that many species might be devoted to experiments in that direction. Some species of _Polyporus_ have been employed as styptics, or beaten till soft and used as amadon. One species in Burmah has a good reputation as an anthelmintic. Some species of _Polysaccum_ and _Geaster_ are employed medicinally in China. Species of _Elaphomyces_ were at one time supposed to possess great virtues now deemed apocryphal. Ergot, developed on rye, wheat, and the germen of various grasses, still maintains its position in the pharmacopœia; but is almost the only fungus now employed, and that sparingly, by the legitimate medical practitioner.

In the Cardiff coal-mines an interesting plant is found, which emits so brilliant a light, that the men have been able to “see their hands by it,” and was visible at a distance of sixty feet. Mr. Worthington Smith, who is an authority for this, observed the same phenomenon in _Polyporus sulfureus_.

While various theories have been recorded as to the physiological cause of the light in cryptogams, and many writers give the most careful details of the structure of the luminous parts, we are unable to go a step farther to explain the cause of the light which appears to be a combustion, but does not consume.