Slide showing a table listing 'reverse mutations in Drosophila Melanogaster.' Slide shows a table listing 'reverse mutations in Drosophila Melanogaster' (fruit fly). Row headings: 'Timofeeff-Ressovsky (175) 4800r', subdivided into 'number of tested gametes' and 'number of reverse mutations'; and 'Johnston and Winchester (76) 3975r', subdivided into 'locus', 'number of tested gametes' and 'number of reverse mutations'. Column headings: 'Locus': 'Chromosome I': 'y', 'sc', 'w', 'ec', 'cv', 'ct', 'v', g2', 'f', and 'Chromosome III': 'ru', 'h', 'th', 'st', 'pb', 'cu', 'so', 'sr', 'es', 'ca'. The table is labelled 'Table 5.' Late 19th to early 20th century