G. MASSEE AND THE FUNGUS FORAY. 137 



within, and of a woody hardness, are fairly abundant in the soil 

 in certain districts, and are known locally as "native bread." 

 Berkeley, recognising the fungous nature of these productions, 

 bestowed on them the name of Mylitta australis^ but was unable 

 to indicate their affinity owing to the absence of reproductive 

 organs. Quite recently these structures have been proved to be 

 the sclerotia of a fungus called Polyporus mylittce, Cke. and 

 Mass. Many other species of fungi produce sclerotia, some of 

 which are not larger than a pin's head. Sclerotia are formed 

 from the vegetative mycelium of the fungus, and functionally are 

 of the same value as the various kinds of resting-spores, remaining 

 for a time in an unchanged condition — sometimes for many 

 years — and eventually giving origin to a new plant, either directly, 

 or from mycelium or conidia, which are first formed. 



Rhizomorphs differ from sclerotia in being long, cord-like bodies 

 formed also from the mycelium. These structures radiate from 

 the point of origin in all directions in the soil, at a depth of a few 

 inches below the surface. When the tip of a rhizomorph comes 

 in contact with the root of a tree it penetrates the tissues, where 

 a dense mycelium soon forms, feeding upon and eventually killing 

 the tree, after which the above-ground fruit of the fungus is 

 developed, new rhizomorphs meanwhile radiating from the new 

 centre of development in search of other victims. Armillaona 

 mellea, a very common British ''toadstool," spreads rapidly by 

 means of subterranean rhizomorphs, and proves very destructive 

 to various species of forest trees. 



