Slide showing 'arrangement of parts of the second (white) and third (stippled) chromosomes in Drosophila melanogaster and D. artificialis.' Slide shows 'arrangement of parts of the second (white) and third (stippled) chromosomes in Drosophila melanogaster and D. artificialis.' Drosophila = fruit fly. At the top of the image there are two sets of chromosomes for both types of fly; the D. melanogaster produces two 'v' shaped gametes (sex-cells) one white, labelled 'a b c' and one shaded, labelled 'd e f'. D. artificialis produces four possible sets of gametes all with the 'a b c' and 'd e f' labels; set (1) is 'a e a' with the 'e' shaded and 'd b c' with the 'd' shaded. Set (2) is as set one, but the second gamete is 'f b c' with 'f' shaded. Set (3) is 'd e f' shaded and 'd b c' with 'd' shaded Set (4) is 'd e f'' shaded and 'f b c' with 'f' shaded. Title below images reads: 'Fig. 20. arrangement of parts of the second (white) and third (stippled) chromosomes in Drosophila melanogaster and D. artificialis. (After Kozhevnikov)'. Late 19th to early 20th century