x INTRODUCTION 



the small effused forms. The hymenium may be spread over 

 radiating gills or plates as in the mushroom, line the interior of 

 tubes or pores as in Polyporus, cover teeth-like projections as in 

 Hydnum, be immersed in a gelatinous mass as in Tremella, or be 

 borne on variously shaped structures known as receptacles as in 

 the Phalloids. 



The sporophore is of different shapes, e.g. globose as in puff- 

 balls, sessile with outstretched flaps as in Stereum, erect, clavate, 

 coralloid or dendroid as in Clavaria, or differentiated into dis- 

 tinct stem, pileus or cap and hymenium-bearing surface as in the 

 mushroom. When young the sporophore is often completely 

 surrounded by a universal veil or membrane termed the volva 

 which is ruptured by the growth of the stem and in many species 

 portions or traces of this remain permanently at the base of the 

 stem. A second membrane or partial veil consisting of either 

 interwoven or arachnoid threads often protects the hymenial 

 surface before it is mature and extends from the stem to the 

 margin of the pileus : it either disappears completely or remains 

 as a ring on the stem, or in appendiculate fragments at the 

 margin of the pileus. The wall surrounding the Gasteromycetae 

 is termed the peridium and consists of one, two, or more layers, 

 the exoperidium to the exterior and the endoperidium to the 

 interior. The peridium sometimes incloses separate hymenium- 

 bearing bodies, the peridiola, which are either free, attached by 

 a cord (funiculus) or form a compound structure. The contents 

 of the peridium are collectively known as the gleba ; in addition 

 to spores there are often certain threads, the capillitium, which 

 arise either directly from the base, from the walls of the peridium 

 or are attached to a denser central portion, the columdla. 



In some cases the external walls of the hyphae deliquesce 

 and this gives a jelly-like consistency to the whole fungus as in 

 Tremella, whilst in other cases the deliquescence is confined to 

 certain areas and constitutes a valuable diagnostic feature. In 

 the genus Coprinus the edge of the gill gradually undergoes a 

 process of autodigestion which ensures the economical dispersion 

 of the spores. The tramal plates of many Gasteromycetae finally 

 dissolve and disappear. All fungi since they have no chlorophyll 

 and are thus unable to form carbohydrates are either saprophytes 

 obtaining their nourishment from dead organic matter or are 



