120 



l)er cent, in Psnlliota arcensis, to 3'0 in Poli/porus fomentarius, all calculated on 

 the dried plant. 



Another class of substances containinc; nitrogen are " alkaloids," or organic 

 bases. These do not afford nutriment, but are characterised by poisonous or 

 medicinal action. They are generally present in very small quantities. We will 

 defer their consideration for the present. 



Starch and cldornphijU, two prominent constituents of other vegetal.s, are absent 

 in fungi, but a near relative of the former, Mi/co-inuUn, closely resembling the 

 inuliu found in Dahlia, roots, &c., has been discovered in a kind of truffle, Ela- 

 phomuces (jfanulatm. It is a white, tasteless substance, soluble in hot water, and 

 not blued by iodine. Its formula is C,. Hj^ O.. 



The Swjars found in fungi are : — 



1. Mannite, identical with that extracted from the manna of Fraxinus ornus 

 and other kinds of Ash. 



2. Mycose or Trehalose, formula the same as cane sugar, Cj., H.,., O^j, con- 

 tained in ex'got and other fungi, and in a peculiar kind of manna from the 

 East. It is colourless, crystallizable, very sweet and soluble, and ferments with 

 difficulty. 



3. An uncrystallizable and easily fermentable sugar, resembling honey or 

 treacle (Isvulose). 



Other obscure gummy substance.-^ are present, and are classed together as 

 "extractive matters." They in'esent little interest. 



Oils and fats occur in most. Ergot contains 30 per cent., consisting of pal- 

 mitin, olein, and possiby peculiar fatty acids. 



The vegetable acids of fungi comprise citric, malic, furaaric, oxalic, agaricic, 

 and others. Famaric acid is closely related to malic, the acid of apples ; it occurs 

 also in Okelidoniam maj us a,nd Funiaria officinalis. Agaricic acid is a crystallized 

 colourless body, discovered by Fleury (J. Pharm. [4] x., 202) in Boletus laricis and 

 Puhjporus officinalis. Hamlet and Plowright established the presence of oxalate of 

 lime, or acid oxalate of potassium, in 30 species of Agaricus. In Fistalina hcpatica 

 they found 0'083 per cent, of free oxalic acid. See the Chemical Society's Journal, 

 1879, for other analyses by them. The " f ungic acid" of Braconnot and earlier 

 observers is a mixture of citric, malic, and phosphoric acids. Some fungi contain 

 free acetic acid. 



Various resins have been isolated, but are not well defined. 



The colouring matters of fungi are often very characteristic, but are chemically 

 still very obscure. Four yellow or orange matters have been made out, distin- 

 guished by giving, when viewed through the spectroscope, two absorption bands in 

 the green or blue, differing in position. Phycoxanthine is yellow. Peziiaxanthinc 

 from Peziza aurantia is orange. There are also two relatives of the Xanthophyll, 

 or yellow colouring matter of leaves. All these are destroyed by light, but are not 

 immediately altered by weak acids or alkalies. 



A red colouring matter was extracted by Phipson from Aj/aricus violaceus. 



From Polyporus purpuraeeus occurring on oaks, and remarkable for turning 

 violet with ammonia, Stahlschmidt (Liebig's Annalen, clxxxvii., 177) extracted 



