105 V. NOTABLE PHENOMENA. THERE are no phenomena associated with fungi that are of greater interest than those which relate to luminosity. The fact that fungi under some conditions are luminous has long been known, since schoolboys in our juvenile days were in the habit of secreting fragments of rotten wood penetrated by mycelium, in order to exhibit their luminous properties in the dark, and thus astonish their more ignorant or incredulous fellows. Rumphius noted its appearance in Amboyna, and Fries, in his Observations, gives the name of Thelephora phosphorea to a species of Corticium now known as Corticium cæruleum, on account of its phosphorescence under certain conditions. The same species is the Auricularia phosphorea of Sowerby, but he makes no note of its phosphorescence. Luminosity in fungi "has been observed in various parts of the world, and where the species has been fully developed it has been generally a species of Agaricus which has yielded the phenomenon."* One of the best-known species is the Agaricus olearius of the South of Europe, which was examined by Tulasne with especial view to its luminosity. In his introductory remarks, he says that four species only of Agaricus that are luminous appear at present to be known. One of them, A. olearius, D. C., is indigenous to Central Europe; another, A. igneus, Rumph., comes from Amboyna; the third, A. noctileucus, Lév., has been dis * M. J. Berkeley, "Introduction to Cryptogamic Botany," p. 265. Tulasne, "Sur la Phosphorescence des Champignons, in "Ann. des Sci. Nat." (1848), vol. ix. p. 338. covered at Manilla by Gaudichaud, in 1836; the last, A. Gardneri, Berk., is produced in the Brazilian province of Goyaz, upon dead leaves. As to the Dematium violaceum, Pers., the Himantia candida, Pers., cited once by Link, and the Thelephora cærulea, D. C. (Corticium cæruleum, Fr.), Tulasne is of opinion that their phosphorescent properties are still problematical; at least no recent observation confirms them. The phosphorescence of A. olearius, D. C., appears to have been first made known by De Candolle, but it seems that he was in error in stating that these phosphorescent properties manifest themselves only at the time of its decomposition. Fries, describing the Cladosporium umbrinum, which lives upon the Agaric of the olive-tree, expressed the opinion that the Agaric only owes its phosphorescence to the presence of the mould. This, however, Tulasne denies, for he writes, "I have had thʊ opportunity of observing that the Agaric of the olive is really phosphorescent of itself, and that it is not indebted to any foreign production for the light it emits." Like Delile, he considers that the fungus is only phosphorescent up to the timo when it ceases to grow; thus the light which it projects, ono might say, is a manifestation of its vegetation. "It is an important fact," writes Tulasne, "which I can confirm, and which it is important to insist upon, that the phosphorescence is not exclusively confined to the hymenial surface. Numerous observations made by me prove that the whole of the substance of the fungus participates very frequently, if not always, in the faculty of shining in the dark. Among the first Agarics which I examined, I found many, the stipe of which shed here and there a light as brilliant as the hymenium, and led me to think that it was due to the spores which had fallen on the surface of the stipe. Therefore, being in the dark, I scraped with my scalpel the luminous parts of the stipe, but it did not sensibly diminish their brightness; then I split the stipe, bruised it, divided it into small fragments, and I found that the whole of this mass, even in its deepest parts, enjoyed, in a similar degree to its superficies, the property of light. I found, besides, a phosphorescence quite as brilliant in all the cap, for, having split it vertically in the form of plates, I found that the trama, when bruised, threw out a light equal to that of their fructiferous surfaces, and there is really only the superior surface of the pileus, or its cuticle, which I have never seen luminous. "As I have said, the Agaric of the olive-tree, which is itself very yellow, reflects a strong brilliant light, and remains endowed with this remarkable faculty whilst it grows, or, at least, while it appears to preserve an active life, and remains fresh. The phosphorescence is at first, and more ordinarily, re cognizable at the surface of the hymenium. I have seen a great number of young fungi which were very phosphorescent in the gills, but not in any other part. In another case, and amongst more aged fungi, the hymenium of which had ceased to give light, the stipe, on the contrary, threw out a brilliant glare. Habitually, the phosphorescence is distributed in an unequal manner upon the stipe, and the same upon the gills. Although the stipe is luminous at its surface, it is not always necessarily so in its interior substance, if one bruises it, but this substance frequently becomes phosphorescent after contact with the air. Thus, I had irregularly split and slit a large stipe in its length, and I found the whole flesh obscure, whilst on the exterior were some luminous places. I roughly joined the lacerated parts, and the following evening, on observing them anew, I found them all flashing a bright light. At another time, I had with a scalpel split vertically many fungi in order to hasten their dessication; the evening of the same day, the surface of all these cuts was phosphorescent, but in many of these pieces of fungi the luminosity was limited to the cut surface which remained exposed to the air; the flesh beneath was unchanged. “I have seen a stipe opened and lacerated irregularly, the whole of the flesh of which remained phosphorescent during three consecutive evenings, but the brightness diminished in intensity from the exterior to the interior, so that on the third day it did not issue from the inner part of the stipe. The phosphorescence of the gills is in no way modified at first by immersing the fungus in water; when they have been immersed they are as bright as in the air, but the fungi which I left immersed until the next evening lost all their phosphorescence, and communicated to the water an already sensible yellow tint; alcohol put upon the phosphorescent gills did not at once completely obliterate the light, but visibly enfeebled it. As to the spores, which are white, I have found many times very dense coats of them thrown down on porcelain plates, but I have never seen them phosphorescent. "As to the observation made by Delile that the Agaric of the olive does not shine during the day when placed in total darkness, I think that it could not have been repeated. From what I have said of the phosphorescence of A. olearius, one naturally concludes that there does not exist any necessary relation between this phenomenon and the fructification of the fungus; the luminous brightness of the hymenium shows, says Delile, 'the greater activity of the reproductive organs,' but it is not in consequence of its reproductive functions, which may be judged only as an accessory phenomenon, the cause of which is independent of, and more general than these functions, since all the parts of the fungus, its entire substance, throws forth at one time, or at successive times, light. From these experiments Tulasne infers that the same agents, oxygen, water, and warmth, are perfectly necessary to the production of phosphorescence as much in living organized beings as in those which have ceased to live. In either case, the luminous phenomena accompany a chemical reaction which consists principally in a combination of the organized matter with the oxygen of the air; that is to say, in its combustion, and in the discharge of carbonic acid which thus shows itself." We have quoted at considerable length from these observations of Tulasne on the Agaric of the olive, as they serve very much to illustrate similar manifestations in other species, which doubtless resemble each other in their main features. Mr. Gardner has graphically described his first acquaintance in Brazil with the phosphorescent species which now bears his name. It was encountered on a dark night of December, while passing through the streets of Villa de Natividate. Some boys were amusing themselves with some luminous object, which at first he supposed to be a kind of large fire-fly, but on making inquiry he found it to be a beautiful phosphorescent Agaric, which he was told grew abundantly in the neighbourhood on the decaying fronds of a dwarf palm. The whole plant gives out at night a bright 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 was called by the inhabitants "flor de coco."* The number of recognized phosphorescent species of Agaricus is not large, although two or three others may be enumerated in addition to those cited by Tulasne. Of these, Agaricus lampas, and some others, are found in Australia. In addition to the Agaricus noctileucus, discovered by Gaudichaud, and the Agaricus igneus of Rumphius, found in Amboyna, Dr. Hooker speaks of the phenomenon as common in Sikkim, but he seems never to have been able to ascertain with what species it was associated. Dr. Cuthbert Collingwood has communicated some further information relative to the luminosity of a species of Agaricus in Borneo (supposed to be A. Gardneri), in which he says, "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 In "Hooker's Journal of Botany " (1840), vol. ii. p. 426. |