External sexual appearances of test worms fed Dugesia ryukyuensis extracts as shown in Table 2. Ventral views of test worms at the fourth week of feeding are shown. Test worms were fed fractions M0 (Fr. M0), M10 (Fr. M10), M30 (Fr. M30), M100 (Fr. M100), H (Fr. H), minced Bdellocephala brunnea (Minced), and chicken liver (Liver). Arrowheads represent an ovary pair (black) and a copulatory apparatus (white). The images are arranged with the anterior to the top. Scale bars represent 2 mm.