120 TEXT-BOOK OF FUNGI 



the growth of fungi, whereas larger proportions of the 

 same salts act as a poison. 



Giinther, Beitr. z. mineralischen Ndhrung d. Pilze ; 

 Inaug. Diss., Erlangen, 1897. 



Molisch, Die Pflanzen\ ihre Beziehungen z. Eisen\ Jena, 

 1892. 



Wehmer, Beitr. z. Kennt. einheimischer Pilze ; Jena, 

 1895. 



EFFECT OF LIGHT AND DARKNESS RESPECTIVELY 

 ON THE GROWTH OF FUNGI 



It is not possible to formulate laws as to the action of 

 light on fungi. The photochemically active rays of the 

 spectrum the blue end destroy bacteria, and according 

 to Klein these same rays prevent the formation of conidia 

 in Botrytis cinerea, which can only be produced in dark- 

 ness. Ferguson's experiments also tend to show that light 

 has an inhibitory effect on the germination of the spores 

 of Agaricus campestris. On the other hand, Brefeld has 

 shown that light is necessary for the perfect development 

 of the sporophore in Pilobolus^ and in species of Coprinus, 

 both of which become abnormal and etiolated in darkness. 



It is well known that many kinds of fungi growing on 

 wood in mines and other dark places develop abnormally, 

 and often assume very fantastic forms. 



Lentinus tigrinus^ a large agaric, when introduced into 

 mines on timber, undergoes strange modifications ; in 

 place of a normal pileus, several branches, more or less 

 resembling stags' horns, are formed ; these are usually quite 

 sterile, or occasionally traces of rudimentary gills are 



