Slide showing two hierarchical diagrams demonstrating the results of crossing 'dextral female with sinistral male and sinistral female with dextral male'. Slide shows two hierarchical diagrams showing the results of crossing 'dextral female with sinistral male and sinistral female with dextral male'. Diagram 1 shows the crossing of dextral female with sinistral male, and diagram 2 shows the crossing of sinistral female with dextral male. There are 2 branches showing the various results of these crossings. No further information provided. Late 19th to early 20th century