THE FUNGI: ASCOMYCETES AND BASIUIOMYCETES 335 



beginning of the gleba, which bears the basidiospores. It is covered by a 

 thin gelatinous endoperidium. The intermediate zone itself undergoes 

 differentiation. It forms outwardly a dense layer, in contact with the glebal 

 folds ; a thick middle zone, and, next to the columella, a close-fitting zone 



. ^'.'■\\\'-\'-\ ■;;:'/;; ' / ///■'^ VOLVA JELLY 



• . ■ ■ ■■ ■. .■,•.:■.■.•'■;./; . < • I ; ■ 



\\ ^ *. '• ■.:.^^•.■W-v^^'■•;'^'^;•/r•^r^''^:c/i:VVv»^■;ii'^;>^■ 





GLEBA ir^: 





ENDOPERIDIUM 



■ ■ .'y'lS.'-. . ft--.- • s 



•.k'-i>c- 





■mi 



.;?.■■■ 



■§>•; 



^■:::-0^:-:r:{A-:-$:i :^:''- axial column 



',ij ' ■ '■■'■■-i'..''. '■'.'■". '. , • •■.-"s- " '■>'';:'■.'■ '. •:!•■& , ■ ' 



! \ :■■■■:.•::■. ■ ■■- •=--.•.■.-■.:.■•• ?.»-■.>:;..■•.•:.••• 



JJ*i- .<■.:■:« 



;::!■■• 





INTERMEDIATE ZONE 



Fig. 329. — Phallus impiuiicus. Vertical section through part of a young fruiting 

 body to show the various layers. {After Fischer.) 



like a sleeve round the columella, which becomes first knotted and later 



spongy. 



The outer dense zone and the thick middle zone contribute to building 

 the pileus, which here forms a bell-shaped structure which lies beneath 

 and within the dome-shaped gleba, instead of being outside and above the 

 spore-bearing layer, as it is in the Agarics. By the time these structures 

 have been formed the gleba has darkened to greenish-grey and has formed 

 a thick layer of basidiospores, and its cells have broken down into a viscid 

 mass. External to it is the layer of volva jelly and the exoperidium of the 

 fructification, enclosing everv'thing else in an " egg " (Fig. 330). The egg 

 stage continues until all the inner tissues have matured. 



Water is now absorbed and the axial column and the spongy sleeve 

 around it become filled with water and expand. This ruptures the egg at 

 the top, and the pileus and gleba are carried rapidly upwards on the expand- 

 ing column, which is now known as the stipe. The exoperidium of the 

 egg is left behind as a sheath at the base of the stipe and forms a volva 



