MYCELIUM 13 



dead trunks in long brown or black cords, as thick as whip- 

 cord, flexible, but tirm, and either branched or joined by 

 cross connectives of the same substance, into a coarse net- 

 work. These Ioiil;' cords may be many feet in length, and 

 whitish internally, with a dark-coloured outer coat or skin. 

 The tips of the growing branches are paler. This peculiar 

 growth is very connnon in mines and other dark places, and 

 glows sometimes with a phosphorescent light. Tulasne 

 examined some specimens with a view to the discovery of 

 the cause of their luminosity, of which Humboldt, amongst 

 others, had given such an elaborate account. He found that 

 all the young branches brightened with a uniform phosphoric 

 light the whole of their length, and also the surface of some 

 of the older branches. The latter when split open were dull, 

 but after exposure for a time to the air they also became 

 luminous. By keeping them moist, they preserved their phos- 

 phorescence for several days. He also states that branches 

 which had been dried for more than a month, when plunged 

 into water, revived, and began to vegetate afresh, in a few days, 

 by sending forth numerous branches, but they were only 

 luminous on the surface of the new parts. One of our 

 commonest Agarics, to be found on nearly every rotten stump, 

 Agaricus melleus, is credited with being the complete develop- 

 ment of one of the species of Rhizomoiyha, which may be 

 stated in this way — the cord-like Rhizomorjpha is simply the 

 persistent mycelium of Agaricus melleus, which grows on 

 rotten stumps. We have no doubt that another form or 

 variety of lihizoviorpha is the mycelium, or vegetative con- 

 dition of Polyporus squamosus, and others, with more or less 

 certainty, are referred to other species of Agaric and Polyponis. 

 Something of the nature of Rhizomorpha is found amongst 

 dead leaves, mostly in long, simple, rigid black threads, which 

 in size and appearance are not unlike horse hair. These are 

 believed to be the mycelium — or rather, we should say, the 

 permanent mycelium, to distinguish it from the filamentouf. 

 white mycelium — of some species of Marasmiits. In tropical 

 and sub-tropical regions these horse- hair filaments are very 

 common amongst dead leaves, and are known to be sterile 

 conditions of several species of Marasmiits. 



