16 TEXT-BOOK OF FUNGI 



other short-lived species. On the other hand, in many 

 perennial forms, as Fomes, Daedalea^ etc., the walls become 

 much thickened and frequently form a mass as hard and 

 durable as wood. Such thick walls often show stratifica- 

 tion, and are frequently coloured, the colouring matter 

 either permeating the entire thickness of the wall, or being 

 confined to certain layers. 



A second type of structure presented by the cell-wall 

 occurs in the members of the family of fungi called 

 Tremellineae, also in the cells forming the cuticle in many 

 Agarics, and elsewhere. The peculiarity consists in the 

 outer layer of the cell-wall becoming resolved into a soft, 

 mucilaginous mass, or in many of the Tremellineae the 

 great bulk of the wall behaves in this manner ; hence in a 

 section the lumens of the cells, containing granular matter, 

 resemble complete cells enclosed in a dense, colourless 

 mass of gelatinous matter. 



Fungi possessing this structure are soft, pliant, and more 

 or less gelatinous when growing; becoming hard, horny, 

 and much contracted when dry, and assume their original 

 appearance when moistened. Among Agarics many species 

 of Cortinarius present this peculiarity, the mucilage being 

 produced in such abundance that it actually drips from the 

 cap and stem. In Mycena rorida and M. epipterygia the 

 stem is covered with dripping gluten derived from deli- 

 quescence of the external layer of the cell-walls. 



The cell-wall in some instances consists of cellulose, as 

 shown by Wager in the case of Cystopus candidus ; but in 

 the majority of instances the insolubility of the wall in an 

 ammoniacal solution of cupric hydrate, and the absence 

 of a blue colouration when treated with iodine and 

 sulphuric acid or with Schulze's solution, prove that the 



