FUNGI. 235 



burned in June. But of far greater importance are the parasitic 

 diseases caused by Fungi, lowly plants without chlorophyll, 

 unable to assimilate carbon, and dependent for their nutriment 

 either on dead organic matter (saphrophytic fungi) or on living 

 animal or vegetable organisms (parasitic fungi). But many 

 saprophytic fungi in our woodlands become parasitic whenever 

 their spores happen to germinate on any wound-surface, how- 

 ever small. 



Parasitic Fungi obtain nourishment through a mycelium with 

 branching filaments (Jiyphce) produced from spores borne by 

 the mycelium: This often assumes a complex form of bundles 

 of strands (rJiizomorpha) with branching root-like processes, or 

 the hyphce form tuber-like masses (sclerotia) whose spores may 

 long lie dormant before finding favourable conditions for ger- 

 minating. Spores are produced in sporangia on special branches 

 (sporophores) of the hyphce, and may be either gonidia (conidia) 

 formed at the points of hyphce growing erect, or sporidia on a 

 promycelium formed by the germination of resting-spores (ovi- 

 spores) produced sexually by the union of two cells or energids. 



In parasitic Fungi the Jiyphce pierce the cells of their host 

 and generate ferments enabling them to dissolve the cellulose and 

 the cell-contents and use them for their own nourishment ; and 

 they may either be autoxenous and complete their generation 

 on one host, or metoxenous and spend part of their life on a 

 second host usually belonging to quite a different kind of plant 

 from the first, and during this intermediate stage the fungus 

 appears to belong to quite a different genus. Trees of all ages 

 are most liable to fungus attack if sickly from any cause what- 

 ever, e.g., unsuitable soil or situation, partial suppression, or 

 damage of any sort ; and many dangerous diseases (e.g., Peziza, 

 Nectria) can only effect an entrance when wounds caused by 

 insects, hail, &c., give their spores a chance of germinating, 

 while others (e.g., Fomes, Agaricus, Rosellinia) spread from root 

 to root by mycelial infection. 



