XXVII 

 THE EFFECTS OF RADIATION ON FUNGI 



Elizabeth C. Smith 



Department of Botany, University of Wisconsin 



Introduction. Visible and ultra-violet radiation: Mycelium — Fruiting structures — 

 Spores — Mutations and saltations — Physiological properties. X-rays. Rays emitted 

 from radioactive substances. General summary. References. 



INTRODUCTION 



Interest in the effects of light on fungi has now lasted well over a 

 century. The early work was of a decidedly qualitative nature and 

 dealt only with light of the visible spectrum. Since that time investiga- 

 tions have been extended to include radiations from the short gamma 

 waves to Hertz waves of a hundred meters. Unfortunately even the 

 most recent work is largely of a qualitative nature. For the most part, 

 when monochromatic light was used, the intensity was not measured, and 

 when the intensity was measured, the quality of the light used was not 

 accurately determined; or the intensity was not kept constant when 

 the wave-length was changed. Throughout most of the work there 

 has been an inadequate control of environmental conditions. These 

 uncontrolled factors have often led to an unfair interpretation of results, 

 and this fact must be given due weight in any attempt to estimate what 

 is known about the effects of radiation on fungi. In view of the absence 

 of any attempt, apparently, to bring together the scattered and extensive 

 literature in this field, and further, in view of the wealth of biological 

 material that has been considered, it has seemed desirable to include in 

 this paper observations that vary greatly in merit or importance. 



VISIBLE AND ULTRA-VIOLET RADIATION 

 MYCELIUM 



Pigmentation. — Since early times botanists have observed that fungi 

 which are growing in the dark are likely to be very pale in color in com- 

 parison with those grown in the light. Bonorden (12) made note of 

 this as early as 1851, and since that time Smith and Swingle (170), 

 Bessey (6), Robinson (159), Milburn (122), Kosaroff (93), Morris and 

 Nutting (127), and others have made similar observations. Humboldt 

 and Seyne (cf. Elfving, 39), however, showed that this was not applicable 

 to all fungi since they found colored varieties growing in complete 

 darkness. Lieske (105) also found that the formation of pigment in 

 Actinomycetes is apparently independent of the action of light. There 



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