1899] MICROSCOPICAL JOURNAL. 189 



the continuance of the species depending entirely on the 

 production of asexual conidia, aided by various vegeta- 

 tive methods whose gradual evolution progressed during 

 the period of decadence of the sexual method of repro- 

 duction. 



The last-mentioned group, including the well-known 

 and universally distributed "toadstools," mushrooms, 

 puffballs, etc., illustrates the highest phase of evolution 

 of the conidial form of reproduction ; which, contrasted 

 with the delicate mould-like form first evolved, shows a 

 remarkable amount of differentiation, being always com- 

 paratively large, often gigantic, and sometimes woody 

 and perennial. 



Among vegetative modes of reproduction two forms are 

 worthy of special mention. Sclerotia are solid aggrega- 

 tions of mycelium of variable size and form, depending 

 on the species to which they belong. In New South 

 Wales, Victoria, and Queensland, certain irregularly 

 globose bodies varying in size from a cricket ball to that 

 of a child's head, dark brown externally, whitish and 

 marbled within, and of a woody hardness, are fairly 

 abundant in the soil in certain districts, and are known 

 locally as "native bread." Berkeley, recognizing the 

 fungus 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 or- 

 gans. 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. 



