FALCK'S THEORY OF RADIOSENSITIVITY 141 



the sun (Sonnenstrahlung) for the dispersion of the spores of Basidio- 

 mycetes " Falck ^ says : " In the Basidiomycetes it is the family 

 of Coprinus-species of which the dispersion of the spores can take 

 place normally only under the influence of radiation. The caps, which 

 in youth are pure white, on ripening take on a dark colour which 

 absorbs radiant energy. I could often observe that the well-known 

 inky deliquescence of Coprinus-species, which results in the flowing 

 away of the majority of the ripe spores, ^ is prevented when the 

 expansion of the pileus takes place under the influence of radiation. 

 In the latter case evaporation of the fluid is so rapid that inky 

 putrefaction does not develop and ail the spores become dispersed." 

 In support of these statements Falck, who appears not to have 

 seen any of my publications on the production and liberation of 

 spores in the genus Coprinus, records a few observations on the 

 effect of radiation on the production of spore-deposits by Coprinus 

 sterquilinus, C. atramentarius, and C. micaceus. 



Falck's statement that " the dispersion of the spores of Coprinus- 

 species can take place normally only under the influence of radia- 

 tion " is not well based and can easily be refuted. Moreover, there 

 does not seem to be any good reason for accepting the suggestion 

 that the blackness of the pileus of such a Coprinus as C. sterquilinus 

 has an important significance in respect to the absorption and 

 utilisation of radiant energy coming from the suii. The following 

 facts and deductions seem to me to be fatal to Falck's theory of 

 radiosensitivity in so far as the genus Coprinus is concerned : 



( 1 ) Large specimens of Coprinus comatus ^ and C. atramentarius 

 have a continuous spore-discharge period of 24-48 hours, so that 

 they shed vast quantities of spores at night as well as in the day. 

 If they were radiosensitive, they would not shed any spores during 

 the hours of darkness, but observation shows that they do shed 

 spores at this time. 



(2) Some species of Coprinus, e.g. C. lagopus and C. macrorhizus , 



^ Richard Falck, Mycologische Untersuchvngen und Berichte, Jena, Heft II, 

 1916, p. 141. 



2 This old conception that during the deliquescence of the gills the majority 

 of the spores become enveloped in the fluid and do not escape into the air is erroneous. 

 Vide these Researches, vol. i, 1909, pp. 206-208. 



3 These Researches, vol. i. 1909, p. 104. 



