Abstract
(1) The author examined survival rates, mutation rates and genetically fixed mutant types by X-ray radiation in Aspergillus sojace.
(2) Conidia of Aspergillus sojae were almost sterilized at 65000r and it will be seen that the mutation rate increased with dosage in a linear manner, the highest dosage, 65000r, resulting in a mutation rate of 6.24 per cent.
(3) It seems that in production of induced mutations soft X-ray radiation was proved less effective as compared with ultraviolet radiation, since sterilities and mutation rates of soft X-ray radiation has been found comparatively low in Aspergillus sojae.
(4) Mutant types by X-ray radiation were almost the same as those by ultraviolet radiation. In the present experiment a new “yeast type” which had not been obtained in the case of ultra-violet radiation was obtained, but no “heavy type” was obtained.
(5) It was observed that morphological changes occurred most frequently in especially “olive” and “light” types through X-ray induced mutants.
