CHAPTER VII 

 GENERAL PHYSIOLOGY OF FUNGI 



The influence of light on the development of the EUMYCETES 

 has been investigated by a number of workers. The influence of light 

 on the direction of growth is known as phototropism. On account of 

 the contradictory evidence of earlier investigations, Friedr. Oltmanns 

 experimented with Phycomyces nitens using a powerful electric arc light. 

 He found that Phycomyces behaved positively phototropic under weak 

 Ulumination, but negatively so under a powerful light. It remained 

 aphototropic with an intermediate illumination, and in yoimg sporangial 

 hyphae with gray sjjorangia, a given degree of Ulumination caused 

 attraction, while with older sporangiophores with blackened sporangia 

 repulsion was noticed. The germination of the spores of such fungi, as 

 Penicillium glaucum, Trichothecium roseum, Fusarium heterosporium, 

 Rhizopus nigricans, does not seem to be affected by light ; while 

 von Wettstein found that light retarded the germination of the spores 

 of Rhodomyces Kochii. The evidence as to the influence of light on 

 the vegetative development seems to be contradictory. J. Schmitz 

 found that Spheeria carpophila grew better in the dark than in daylight. 

 G. Winter found Peziza Fuckeliana to cease growth in the dark and the 

 fungus perishes if light be long excluded. Mac Dougal^ experimented 

 with Coprinus stercorarius. He found that it developed a much greater 

 length than the normal in darkness, but the fruit bodies remained in 

 1 rudimentary or incomplete stage. After growth had proceeded in 

 this manner for some time the illumination of the body was followed 

 by the production of fruit bodies in a manner demonstrating most 

 conclusively that the action in question was due to a purely stimula- 

 tive action of light, since the rays did not participate in any synthesis 

 jf material. 



The rate of cell reproduction does not seem to be influenced by the 

 Dresence or absence of light. In many fungi, the formation of a 



' Mac Dougai., D. T.: The Influence of Light and Darkness upon Growth and 

 Development. Memoirs of the New York Botanical Garden, ii (1903: 279). 



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