IX 



INTRODUCTION 



FUNGI are non-chlorophyllous cryptogams reproduced by spores. 

 In the larger fungi these spores are borne either to the exterior 

 of a cell called the basidium or are contained within a sac-like 

 cell called the ascus. Fungi with basidia constitute the 

 BASIDIOMYCETAE, whilst those with asci are known as the 

 ASCOMYCETAE. The present work deals only with the former 

 group. 



The Basidiomycetae were, until quite recently, divided into 

 two main groups, HYMENOMYCETAE and GASTEROMYCETAE : in 

 the former the spores are freely exposed to the air at maturity, 

 whilst in the latter they remain inclosed within the body of the 

 fungus. The spores on germination either give rise to threads or 

 hyphae (collectively known as the mycelium or spawn) or they 

 produce secondary spores termed sporidiola which on germina- 

 tion develop the mycelium. This mycelium constitutes the 

 vegetative portion of the fungus and consists of septate hyphae, 

 in some cases with lateral outgrowths known as clamp connections 

 which arise near the septa and connect two adjacent cells. The 

 mycelium is either filamentous or forms cord-like strands. At 

 their extremities the hyphae give rise to other hyphae which 

 terminate in basidia, sterile paraphyses which act as spacing 

 elements and in some cases other sterile cells termed cystidia. 

 These elements together constitute the hymenium and generally 

 form a homogeneous layer but in some of the Gasteromycetae the 

 basidia are irregularly distributed as in Scleroderma. The tissue 

 between the hymenial layers is known as the trama. The basidium 

 may consist either of a continuous cell, or be longitudinally 

 divided, or transversely septate. It is usually surmounted at the 

 apex by short stalks, the sterigmata, which bear the spores; some- 

 times these are lateral or arise from the division of the transversely 

 septate basidia: sometimes the spores are borne directly on the 

 hyphae. In some genera long vesicular hyphae are present which 

 traverse the tissue in various directions and these are often filled 

 with a granular coloured or colourless latex. The vegetative 

 hyphae constitute the main portion of the sporophore except in 



