Slide showing diagrams regarding the mating of neutral females with all-male cultures. Slide shows diagrams regarding the mating of neutral females with all-male cultures. Writing at the top of the slide reads: 'b. The crucial experiment. Recently however, a crucial experiment could be carried out on an absolutely irreproachable scale. A considerable number of males from all-male cultures (F1 weak x strong), as a matter of fact two entire brotherhoods, were mated to neutral females. If F is situated within the Y-chromosome, the following result was expected: Neutral females x all male culture (Y Fneu) (X Mneu_) x 1/2 (X Mst) (X Mw) or 1/2 (Y Fw) (X Mst).' After this text, there are diagrams demonstrating such mating of chromosomes. Late 19th to early 20th century