128 



EFFECTS OF RADIATION ON FUNGI 



meister (1909) exposed Botrytis cinerea to illumination in which 

 portions of the spectrum were screened out. The results of their 

 studies and those of others are contradictory. In red lisrht and 

 in darkness few conidia of B. cinerea were noted by Reidemeister 

 (1909), but they formed abundantly in blue light. Colonies of 

 Aspergillus clavatus grown in blue light produced tall conidio- 



Fig. 15. Culture of Aspergillus clavatus grown in total darkness or in red 



light. 



phores with a few short ones, whereas in red light and in dark- 

 ness all were short [Wolf (1938)]. 



Since some fungi produce concentric zones in total darkness, 

 the alternation of day and night must be regarded as only one of 

 the complex factors involved in this phenomenon. Bisbv (1925) 

 induced zonation in Fusarium discolor sulphur eum in total dark- 

 ness if the temperature was alternated. The effect of temperature 

 has been substantiated by more recent studies with other species. 

 In an analysis of his studies on Fusarium and Monilia jructigena 

 Brown (1925) showed that zonation in response to light changes 

 is correlated with the following factors: (1) the capacity of the 



