In the 1920's and 1930'3 researchers were looking for organisms in which to test hypotheses regarding the new field of genetics. Neurospora was selected for use because it grew rapidly on chemically defined medium and reproduced in the laboratory. It has a haploid genome and the production and isolation of morphological or biochemical mutants is straight forward.
Four figures were designed and commissioned by George Beadle and were published in at least two places:
American Scientist 34:31-53 (1946) 'Genes and the chemistry of the organism,' and
Fortschritte der Chemie organischer Naturstoffe 5:300-330 (1948) 'Some recent developments in chemical genetics'.
Beadle and Tatum won the 1958 Nobel prize for their demonstration of the One-gene, One-enzyme hypothesis and they shared the prize with Joshua Lederberg who had demonstrated transduction in Salmonella.
The drawings show, among other things, the process of isolation of auxotrophic mutants, the screening of auxotrophic mutants, the segregation of mutants, and the chromosome events associated with this segregation.
The original drawings are held at the Fungal Genetics Stock Center.