Hermann Joseph Muller ( or H. J. Muller ) ( December 21 , 1890 - April 5 , 1967 ) was an American geneticist , educator , and Nobel laureate best known for his work on the physiological and genetic effects of radiation ( X-ray mutagenesis ) as well as his outspoken political beliefs .
Hermann Joseph Muller , generally known as H. J. Muller , ( 21 December 1890 - 5 April 1967 ) was an American geneticist , educator , and Nobel laureate .