EFFECTS OF RADIATION ON FUNGI 899 



which are not known to be occasionally produced by these fungi in the 

 natural course of events. Perithecia were produced in cultures of 

 Glomcrella cingulata (173, 174), CoUetotrichum lagenarium (178), and a 

 species of Coniothyrium (173). Pycnidia were formed in Coniothyrium 

 (176). These changes were all brought about by exposures of less than 

 1 min. at a distance of 20 cm. from the lamp. None of the changes was 

 hereditary. However, in only a few of the many species which he irra- 

 diated was he able to produce any change in the method of reproduction. 



As early as 1852, Tulasne (cf. MacDougal, 112) observed that the 

 sporophores of some fungi produce spores only in the light. Other species 

 than those observed by Tulasne were found by Brefeld (16), Lendner 

 (102), and Grantz (59) to require light for spore production. Coprinus, 

 Sphaerobolus, and Piloholus are some of the fungi which fall in this group. 

 Loew (106) found, however, that spore production in Penicillium, Tri- 

 chothecium, and Mucor stolonifer is independent of light. For those 

 fungi which do require light to produce spores Brefeld (16) found that 

 only a few hours' exposure is sufficient to induce complete development 

 in the dark. The studies which have been made to determine which 

 wave-lengths are necessary for spore production are contradictory, 

 probably owing to the variety of environmental conditions and species 

 employed. Such studies were made by Klein (90), Costantin (cf. Moreau 

 and Moreau, 126), Reidemeister (156), Moreavi and Moreau (126), 

 Rabinovitz-Sereni (152), and Purvis and Warwick (150). No general 

 conclusions can be drawn from this work. 



Long exposures to ultra-violet radiation decrease spore production, 

 whereas short exposures stimulate. The inhibitive effects of relatively 

 long exposures were noted by Purvis and Warwick (150), Porter and 

 Bockstahler (147), Hutchinson and Ashton (79), Stevens (176), and 

 Smith (169). One of the earliest reports of stimulation of spore produc- 

 tion with small amounts of radiation was made by Purvis and Warwick 

 (150). They exposed portions of a Mucor culture for 10 to 20 min. to the 

 direct radiation of a Bach quartz-mercury-vapor lamp placed at 30 cm. 

 from the culture. The temperature of the culture was never higher 

 than 30°C. The portion of the culture below the center of the aperture 

 was killed, but at the edges of the irradiated region spores were produced 

 in great abundance. Since that time a number of investigators including 

 Stevens (176), Dillon- Weston (33), Hutchinson and Ashton (79), Ramsey 

 and Bailey (154), Bailey (2), and Smith (169) have tried short exposures 

 to ultra-violet radiation and obtained marked stimulation to spore 

 production in a wide variety of species. Smith made spore counts and 

 gave curves showing quantitatively the effects of different short exposures. 

 Both Ramsey and Bailey, and Smith reported that increased spore 

 production does not seem to be directly correlated with inhibition in the 

 growth rate. According to Bailey and to Ramsay and Bailey increasing 



