908 BIOLOGICAL EFFECTS OF RADIATION 



substances. Retardation of vegetative growth was reported by Dauphin 

 (27), Dautwitz (cf. Stoklasa and Penkava, 181), Fabre (43), Miescher 

 (121), Rivera (158), Johnson (83), and Nadson (130). Rather interesting 

 morphological changes in the hyphae have been observed with sublethal 

 doses. Nadson (132) reported that the protoplasm becomes less trans- 

 parent, granulation occurs, many vacuoles appear, and there is an increase 

 in size of the cells. Yeasts form cysts which are not affected by the rays. 

 Similar though less detailed observations were made by Dauphin (27), 

 Purvis and Warwick (150), and Kotzareff and Chodat (94). 



Kotzareff and Chodat (94), Nadson (131), and Fabre (43) all reported 

 that small doses stimulate cell division at least temporarily. Nadson 

 considered the action of radium as an aging process which accelerates the 

 vital processes and brings about a premature death of the cell. This is in 

 accord with a number of observations made on green plants. Lacassagne 

 (96) was unable to observe any stimulation of the growth of yeast cells, 

 owing, possibly, either to the doses which were used or to the method of 

 measuring stimulation. 



Sartory, Sartory, and Meyer have published a series of papers on the 

 effects of radium on the fruiting bodies of Aspergillus fumigatus and 

 Mucor spinosus. They reported that in a "dissociated" medium radia- 

 tion stimulates the formation of fruiting structures in A. fumigatus 

 especially if irradiation is discontinuous, whereas if the medium is "undis- 

 sociated" there is a delay in the appearance of normal fruiting bodies 

 (161). They found that if this fungus is grown on gelatinized carrot 

 juice (pH 4.7) dissociated by sodium chloride, it produces asci and 

 ascospores under the action of radium (162). They were also able to 

 cause the production of sex organs in M. spinosus on the same medium 

 (163). 



Ceresoli (23), Dautwitz (cf. Stoklasa and Penkava, 181), Fabre (43), 

 and Ingber (82) all reported a retardation or partial suppression of spore 

 production by radiation. Ingber reported in addition that small doses 

 may stimulate spore production. 



Retardation or complete suppression of spore germination by radiation 

 wasreportedbySartory, Sartory, and Meyer (163), Dautwitz (cf. Stoklasa 

 and Penkava, 181), Fabre (43), Pichler and Wober (146), and Dauphin 

 (27). Sartory, Sartory, and Meyer found that spores resist much higher 

 doses of radiation if the medium is dissociated by thorium. Neidhart 

 (137) reported that smaller doses of radium are necessary to kill the 

 germinating than the resting spores of Sporotrichum Beurmanni. 



Studies have been made of the effects of the rays emitted by radio- 

 active substances on various physiological processes in fungi. Stoklasa 



(180) reported that respiration is increased and Stoklasa and Penkava 



(181) later found tiiat while respiration is increased by alpha radiation, 

 it is decreased by gamma or by a mixture of beta and gamma radiations. 



