Slide showing a list of combinations regarding zygotes. Slide shows a list of combinations regarding zygotes. The list reads as follows: '(Fw) Mw Y = weak [female] (Fst) Mst Y = strong [female] (Fst) Mw Y = heterozygous normal [female]1 (Fw) Mst Y = intersexual [female] (Fw) Mw Mw = weak [male] (Fst) Mst Mst = strong [male] (Fw) Mst Mst = normal [male]2 (Fw) Mst Mw = heterozygous normal [male] (Fst) Mst Mw = heterozygous normal [male]3 (Fst) Mw Mw = intersexual [male]'. Words in square brackets have been inserted by the archivist as replacements for the male and female symbols used in the slide. Late 19th to early 20th century