proceeds rapidly till the depth of intensity has been gained. This blue colour is so universally confined to dangerous species that it is given as a caution that all species which exhibit a blue colour when cut or bruised, should on no account be eaten. The degree of intensity varies considerably according to the condition of the species. For example, Boletus cærulescens is sometimes only very slightly, if at all, tinged with blue when cut, though, as the name implies, the peculiar phenomenon is generally highly developed. It cannot be said that this change of colour has as yet been fully investigated. One writer some time since suggested, if he did not affirm, that the colour was due to the presence of aniline, others have contented themselves with the affirmation that it was a rapid oxidization and chemical change, consequent upon exposure of the surfaces to the air. Archdeacon Robinson examined this phenomenon in different gases, and arrived at the conclusion that the change depends on an alteration of molecular arrangement.*

One of the best of the edible species of Lactarius, known as Lactarius deliciosus, changes, wherever cut or bruised, to a dull livid green. This fungus is filled with an orange milky fluid, which becomes green on exposure to the air, and it is consequently the juice which oxidizes on exposure. Some varieties more than others of the cultivated mushroom become brownish on being cut, and a similar change we have observed, though not recorded, in other species.

The presence of a milky juice in certain fungi has been alluded to. This is by no means confined to the genus Lactarius, in which such juice is universal, sometimes white, sometimes yellow, and sometimes colourless. In Agarics, especially in the subgenus Mycena, the gills and stem are replete with a milky juice Also in some species of Peziza, as for instance in Peziza succosa, B., sometimes found growing on the ground in gardens, and in Peziza saniosa, Schrad., also a terrestrial species, the same phenomenon occurs. To this might be added such species as Stereum spadiceum, Fr., and Stereum sanguinolentum,

• Berkeley, "Introduction to Crypt. Bot." p. 266.

Fr., both of which become discoloured and bleeding when bruised, while Corticium lactescens distils a watery milk.

Fungi in general have not a good repute for pleasant odours, and yet it must be conceded that they are not by any means devoid of odour, sometimes peculiar, often strong, and occasionally very offensive. There is a peculiar odour common to a great many forms, which has come to be called a fungoid odour; it is the faint smell of a long-closed damp cellar, an odour of mouldiness and decay, which often arises from a process of eremocausis. But there are other, stronger, and equally distinct odours, which, when once inhaled, are never to be forgotten. Amongst these is the fetid odour of the common stinkhorn, which is intensified in the more beautiful and curious Clathrus. It is very probable that, after all, the odour of the Phallus would not be so unpleasant if it were not so strong. It is not difficult to imagine, when one encounters a slight sniff borne on a passing breeze, that there is the element of something not by any means unpleasant about the odour when so diluted; yet it must be confessed that when carried in a vasculum, in a close carriage, or railway car, or exposed in a close room, there is no scruple about pronouncing the odour intensely fetid. The experience of more than one artist, who has attempted the delineation of Clathrus from the life, is to the offect that the odour is unbearable even by an enthusiastic artist determined on making a sketch.

Perhaps one of the most fetid of fungi is Thelephora palmata. Some specimens were on one occasion taken by Mr. Berkeley into his bedroom at Aboyne, when, after an hour or two, he was horrified at finding the scent far worse than that of any dissecting room. He was anxious to save the specimens, but the scent was so powerful that it was quite intolerable till he had wrapped them in twelve thick folds of the strongest brown paper. The scent of Thelephora fastidiosa is bad enough, but, like that of Coprinus picaceus, it is probably derived from the imbibition of the ordure on which it is developed. There needs no stronger evidence that the scent must not only be powerful, but unpleasant, when an artist is compelled, before a rough sketch is more than half finished, to throw it away, and seek relief in the open air. A great

number of edible Agarics have the peculiar odour of fresh meal, but two species, Agaricus odorus and Agaricus fragrans, have a pleasant anise-like odour. In two or three species of tough Hydnum, there is a strong persistent odour somewhat like melilot. or woodruffe, which does not pass away after the specimen has been dried for years. In some species of Marasmius, there is a decidedly strong odour of garlic, and in one species of Hygrophorus, such a resemblance to that of the larva of the goat moth, that it bears the name of Hygrophorus cossus. Most of the fleshy forms exhale a strong nitrous odour during decay, but the most powerful we remember to have experienced was developed by a very large specimen of Choiromyces meandriformis, a gigantic subterranean species of the truffle kind, and thisspecimen was four inches in diameter when found, and then partially decayed. It was a most peculiar, but strong and unpleasantly pungent nitrous odour, such as we never remember to have met with in any other substance. Peziza venosa is remarkable when fresh for a strong scent like that of aquafortis.

Of colour, fungi exhibit an almost endless variety, from white, through ochraceous, to all tints of brown until nearly black, or through sulphury yellow to reds of all shades, deepening into crimson, or passing by vinous tints into purplish black. These are the predominating gradations, but there are occasional blues and mineral greens, passing into olive, but no pure or chlorophyllous green. The nearest approach to the latter is found in the hymenium of some Boleti. Some of the Agarics exhibit bright colours, but the larger number of bright-coloured species occur in the genus Peziza. Nothing can be more elegant than the orange cups of Peziza aurantia, the glowing crimson of Peziza coccinea, the bright scarlet of Peziza rutilans, the snowy whiteness of Peziza nivca, the delicate yellow of Peziza theleboloides, or the velvety brown of Peziza repanda. Amongst Agarics, the most noble Agaricus muscarius, with its warty crimson pileus, is scarcely eclipsed by the continental orange Agaricus cæsarius. The amethystine variety of Agaricus laccatus is so common and yet so attractive; whilst some forms and

species Russula are gems of brilliant colouring. The golden tufts of more than one species of Clavaria are exceedingly attractive, and the delicate pink of immature Lycogala epidendrum is sure to command admiration. The minute forms which require the microscope, as much to exhibit their colour as their structure, are not wanting in rich and delicate tints, so that the colour-student would find much to charm him, and good practice for his pencil in these much despised examples of low life.

Amongst phenomena might be cursorily mentioned the peculiar sarcodioid mycelium of Myxogastres, the development of amoeboid forms from their spores, and the extraordinary rapidity of growth, as the well-known instance of the Reticularia which Schweinitz observed running over iron a few hours after it had been red hot. Mr. Berkeley has observed that the creamy mycelium of Lycogala will not revive after it has become dry for a few hours, though so active before.

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VI.

THE SPORE AND ITS DISSEMINATION.

A WORK of this character would hardly be deemed complete without some reference to the above subject, which has moreover a relation to some of the questions discussed, and particularly of spore diffusion in the atmosphere. The largest spore is microscopic, and the smallest known scarcely visible under a magnifying power of 360 diameters. Taking into account the large number of species of fungi, probably scarcely less numerous than all the flowering plants, and the immense number of spores which some of the individuals produce, they must be exceedingly plentiful and widely diffused, though from their minuteness not easy to be discerned. It has been attempted to estimate the number of spores which might be produced by one single plant of Lycoperdon, but the number so far exceeds that which the mind is accustomed to contemplate that it seems scarcely possible to realize their profusion. Recent microscopic examinations of the common atmosphere* show the large quantity of spores that are continually suspended. In these investigations it was found that spores and similar cells were of constant occurrence, and were generally present in considerable numbers. That the majority of the cells were living, and ready to undergo development on meeting with suitable conditions, was very manifest, as in those cases in which preparations were retained under observation for any length of time, germination rapidly took place in many of the cells. In few instances did any development take place,

*

Cunningham, in "Ninth Annual Report of the Sanitary Commissioner with the Government of India." Calcutta, 187 2.