 After her year @-@ long temporary appointment , McClintock accepted a full @-@ time research position at Cold Spring Harbor Laboratory . There , she was highly productive and continued her work with the breakage @-@ fusion @-@ bridge cycle , using it to substitute for X @-@ rays as a tool for mapping new genes . In 1944 , in recognition of her prominence in the field of genetics during this period , McClintock was elected to the National Academy of Sciences — only the third woman to be elected . That same year , she became the first female president of the Genetics Society of America ; she was elected its vice @-@ president in 1939 . In 1944 she undertook a cytogenetic analysis of Neurospora crassa at the suggestion of George Beadle , who used the fungus to demonstrate the one gene – one enzyme relationship . He invited her to Stanford to undertake the study . She successfully described the number of chromosomes , or karyotype , of N. crassa and described the entire life cycle of the species . Beadle said " Barbara , in two months at Stanford , did more to clean up the cytology of Neurospora than all other cytological geneticists had done in all previous time on all forms of mold . " N. crassa has since become a model species for classical genetic analysis . 
