Slide showing four diagrams demonstrating 'the first meiotic division in Oenothera lamarckiana'. Slide shows four diagrams demonstrating 'the first meiotic division in Oenothera lamarckiana'. Diagrams are labelled 'a' to 'd'. Diagram 'a' shows 'Two-strand Pachytene'. Diagram 'b' shows 'Diplotene' and diagram 'c' shows 'diakinesis'. Diagram 'd' shows 'first metaphase'. Title below image reads: 'Fig 19 - diagrams of the first meiotic division in Oenothera lamarckiana. The chromosomes are labelled 1-14. 1 and 2 form a bivalent, being homologous throughout. 3-14 form a ring of 12 chromosomes united by 12 chiasmata after diplotene. The middle segments containing the velans and gaudens genes are labelled v and g. These segments contain median spindle attachments. At anaphase chromosomes 3, 5, 7, 9, 11 and 13 go to 1 pole, 4, 6, 8, 10, 12 and 14 to the other.' Oenothera lamarckiana is commonly called 'Evening Primrose'. Late 19th to early 20th century