G THE PARASITIC FUNGI. 



known as Trametes radiciperda, is an undoubted parasite of 

 pines, spruces, and other trees, yet on timber in mines ^ it 

 grows luxuriantly, and reproduces abundantly from sporophores, 

 which, however, differ somewhat from the typical form. Again, 

 the rhizomorph-strands of Agaricus melleus grow under dead 

 bark, in the earth, in mines, and in wooden water-pipes, while 

 other forms of its mycelium are completely parasitic ; thus 

 the apices of the rhizomorphs penetrate the bark of young 

 conifers, and, in the form of a mycelium, live parasitic on rind, 

 bast, and cambium. 



Polyporus vaporarius, a true parasite on living Scots pine, 

 is also an enemy of timber in newly-buUt structures, or in 

 subterranean spaces and cellars, so long as it can obtain the 

 necessary moisture. Polyporus sidpTiureus produces sporophores 

 on the bark of living trees, as well as on the dead stools of 

 felled trees. Many other related forms would probably be able 

 to live on dead timber if they were not dependent on a certain 

 degree of moisture, and could submit to drying-up as easily as, 

 for example, Polyporus ahietinus, a true saprophyte, and one of 

 the most common enemies of old wooden bridges. 



Fungi from other groups are also known to effect an entrance 

 into the wood of trees through wounds only, yet when once in, 

 they spread rapidly, and at length bring about the death of their 

 host The spores of Ciwurhitaria labvmi were demonstrated 

 by me to germinate on the laburnum, on wounds produced 

 by hail and otherwise, and to send into the wood so exposed 

 a mycelium, which spread through the vessels and into the rind, 

 killing all the tissues on its way. Similarly Nectria cinnabarina, 

 after it has killed its host, lives thereon as a saprophyte, and 

 develops patches of conidia and perithecia on the dead bark. 

 Peziza Willkommii, although really a strict parasite on the living 

 rind, yet continues to grow and to reproduce itself on the dead 

 branches. 



Hemi-parasites. 



If the examples already given, i.e. Mucor, Penicillium, Botrytis, 

 Pythium, are typical of hemi-saprophytes, then there may arise 

 a doubt whether the remainder, the wood-destroying Polyporeae, 

 Nectria, CiKuriitaria, and Agaricus mellefiis, should not be regarded 



• Harz, Botan. CentraiblaU, 1888, Vol. xxxvi. ; Magnus, Botan. Vtrein d. Prov. 

 Brandeiibury, 1888. 



