VARIATION IN PENICILLIUM NOTATUM INDUCED BY THE BOMBARDMENT OF SPORES WITH NEUTRONS'

Investigators who have studied the production of penicillin by Penicllium notatum are well aware of the fact that individual strains of this mold differ greatly in their capacity to produce the antibiotic substance. Since it is reason-able to suppose that the reactions involved in the formation of antibiotic sub-stances may be genetically controlled biochemical reactions, it seemed probable that induced variation of P. notatum might bring forth more highly productive strains. In the attempt to induce variation of fungi, many workers have employed such agents as heat, chemicals, ultraviolet light, and x-rays. Although positive results on mutations produced by chemical treatment have been reported, it is questionable whether the substances used could have reached the nuclei of the organisms so as to bring about demonstrable genetic changes. Since the dis-covery that x-rays induce gene mutations, radiation has become an important tool in genetic research, and in all organis adequately tested the so-called ionizing radiations have been found to produce mutations (Fano and Demerec