born Nov. 29, 1907, Pisa, Italy
died Sept. 24, 1999, near Zermatt, Switz.
Italian-born British geneticist.
In 1938, influenced by Hermann Joseph Muller , he designed a method for studying genetic differences among species that usually produce sterile hybrids when interbred. His technique permitted him to study evolutionary divergence in the fruit fly. His conviction that research in microbial genetics could lead to increased production of penicillin, much needed in World War II, led him to the genetics of fungi, and in 1950 he found that recombination of genes can occur in the fungus Aspergillus nidulans without sexual reproduction. Nonsexual gene recombination became a useful technique in exploring the nature of gene action.