714 SYSTEMATIC BOTANY. 



melia, Variolaria, 8fc., are also sometimes employed in' Britain and elsewhere 

 in the manufacture of orchil. (See these species above.) Orchil and cud- 

 bear are used for staining and dyeing purple and red colours, and also occa- 

 sionally as tests for acids and alkalies. Litmus is employed as a test for 

 alkalies, acids, and some salts with a basic reaction. A decoction of orchella 

 weed possesses mucilaginous, emollient, and demulcent properties, and has 

 been used in coughs, catarrhs, &c. 



Natural Order 294. Fungi. — The Mushroom Order. — Pa- 

 renchymatous cellular plants, producing their fructification in 

 the air; growing in or upon decaying or living organic sub- 

 stances, and nourished through their vegetative structure called 

 the spawn or mycelium. (See page 385, and ^95. 150 — 152, 

 and 824). Fructification various. (See pages 385 — 388, and 

 figs. 824—827.) 



Distribution, ^c. — They abound in aU parts of the world. 

 Examples : — Agaricus, Polyporus, Hydnum, Phallus, Lyco- 

 perdon, Bovista, Torula, Puccinia, Uredo, Botrytis, Morchella 

 Peziza, Tuber, Sphoeria, Mucor. The number of species is 

 estimated at about 4000. 



Properties and Uses. — Fungi have very variable properties. 

 Some are medicinal, others edible, and others are deadly poi- 

 sons. Many deaths have occurred from poisonous fungi having 

 been mistaken for edible ones, and science as yet affords no 

 certain characters by which tliey may be distinguished; some 

 general characters, however, will enable us in most cases to 

 do so ; these may be tabulated as follows : — 



Edible Mushrooms, 



1. Grow solitary, in dry airy places. 



2. Generally white or brownish. 



3. Have a compact brittle flesh. 



4. Do not change colour when cut by the action of the air 

 ."i. Juice watery. 



6. Odour agreeable. 



7. Taste not bitter, acrid, salt, or astringent. 



Poisonous Mushrooms. 



1. Grow in clusters, in woods, and dark damp places. 



2. Usually with bright colours. 



3. Flesh tough, soft, and watery. 



4. Acquire a brown, green, or blue tint, when cut and exposed to the air. 



5. .Tuice often milky. 



6. Odour commonly powerful and disagreeable. 



7. .Have an acrid, astringent, acid, salt, or bitter taste. 



Wc should, moreover, avoid all fungi which insects will not 

 touch ; and those which have scales or spot.s on their surface ; 

 and whatever may be the apparent qualities of the fungi, we 

 should use with caution all which liave arrived at their full 

 development, or when they exhibit any signs of change. When 

 we arc doubtful as to the qualities of the mushrooms, it is very 

 advisable to cut them into slices, and macerate them in vinegar 



