XrV. AJjGM. 965 



Their colour is moat variable, and often depends on the age and degree of moisture of the species. 

 In general it is not brilliant : if we find yellow, red, blue, violet, white, and black Fungi, the tinfa are 

 usually subdued, and the green one (Peaiza eeruginosa) cannot be compared as to tint with the green of 

 chlorophyll. The peculiar tissues of Fungi present the same variety of shades ; although white is the 

 chief colour of Agarics, and lusset that oi Boleti, yet some change quickly to indigo the moment they 

 are broken and their tissue exposed to the air. Certain Fungi are phosphorescent: several exotic Agarics, 

 and those of the Olive {A. oharius), of the south of Europe, present this singular phenomenon. 



If plunged in water, and exposed to the action of light, Fungi give oif hydrogen, azote, and carbonic 

 acid ; nevertheless, according to some experimentalists, Tremelke behave differently, and give off oxygen 

 when they are placed in the same conditions as Phsenogams provided with green matter. 



A Fungus, if broken or cut in one of its parts, continues to live ; but the wound does not heal, and 

 the exposed surfaces wither or dry. 



Properly speaking, only one species of Fungus is cultivated; but A. JEgerita is sometimes produced 

 by burying round slabs of Poplar, and A. albellus by moving earth from one place to another. The 

 young Truffle-oaks do not give rise to Truffles; but it often happens that the presence of young plants in 

 suitable soil tends to the production of these valuable tubers. 



The chemical composition of Fungi is somewhat complicated : they contain, in addition to water, 

 which sometimes forms nine-tenths of their substance, cellulose, associated vsdth other peculiar elements, 

 which together constitute what chemists have termed fmighxe ; general principles, as agaricine, viscosine, 

 mycetide, a certain quantity of alhtimime, as well as an azotized fatty matter ; some colouring, resinous or 

 hydrogenized principles ; fixed or volatile oils ; an amyloid substance, turning blue with iodine ; ferment- 

 able sugar ; mannite ; glucose, more abundant in old Fungi than in young ones (probably the result of 

 the transformation of other hydro-carbons) ; propylamine is also extracted from them, which gives the 

 smell of rotten fish to Bunt and the Ergot of Rye ; finally, amanif.ine, a principle of which the poisonous 

 actioh> is only too certain, but the atomic composition of which is not yet known. Besides these substances, 

 Fungi contain phosphates, malates, oxalates, and citrates of lime, magnesia, and alumina, and even free 

 oxalic acid and chloride of potassium. The spores of Fungi are so minute, says Fries, that a single 

 Meticularia possesses millions; so subtle as to be individually imperceptible, so light that they are carried 

 by the atmospheric vapours, and so numerous that it is diflicult to imagine a space too small to contain 

 them, as is shown by the learned and ingenious experiments of M. Pasteur, and the difficulty of guarding 

 against the introduction of Penicillium, glaucum in a multitude of experiments upon the spontaneous gene- 

 ration of Fungi. Fermentation and the mysterious part which it plays in the decomposition of organic 

 matter is closely connected with the existence of the plants belonging to the genera Cryptocoeeus, Bor- 

 misdum, &c., which consist of free oblong or ovoid microscopic cells. 



Fungi are of scarcely any use in the arts, with the exception of amadou and some colouring principles, 

 among which we shall only quote that of Dothidea tinctoria, which lives on the leaves of a Baccharis of 

 New Granada, and yields a very solid green dye. In medicine none are now used but the Ergot of Rye 

 or Wheat, to arrest certain haemorrhages, and to assist in childbirth. The Ergot of Paspalum ciliare, which 

 has no resemblance in form or colour to that of Rye, is similarly used in North America. Dr. Roulin saw, 

 in New Granada, mules, deer and parrots seriously injured, and even die after eating ergoted Maize, the 

 taste of which was disguised by that of the Sphacelia, which is rather sweet ; this Ergot is called in the 

 country peladero, on account of its causing to animals th« loss of hair, nails, claws and beak. It is 

 known that flour which contains a certain quantity of Ergot becomes extremely poisonous, and causes 

 very serious diseases, described by doctors as ergotism and dry caries of the joints ; diseases which in 

 certain rainy years have raged in an endemic form, like cholera, in various places. J. H. LfivBii,L:fi. 



XIV. ALG^, Jussieu, Agardh, Lamouroux, Kutzing, &c. 



Cellula/r Acotyledons, aquatic, or growing on damp ground, always exposed to the 

 light ; very various inform, texture and colour ; free, or fixed hy roots or fulcra; sometimes 

 microscopic, unicellula/r; sometimes furwished with a simple or branched stem, terminated 

 hy fronds, always deprived of stomata. Eeproduotive oegans sometimes of one kind 

 only, resulting from the concentration of the green matter, and becoming spores fwmished 



