1. Paramecium, various stages of conjugation. 2. Hydra with bud whole mount. 3. Hydra testis whole mount. 4. Hydra ovary whole mount. 5. Sheep tenia (Moniezia), whole mount. 6. Schistosoma japonicum, male and female in copula. 7. Ascaris transversal section of male in region of sex organs. 8. Ascaris transversal section of female in region of sex organs. 9. Ascaris female: uterus with differently developed embryos, whole mount. 10. Cyclops whole mount with egg sacs. 11. Honey bee (Apis mellifica), ovary of the queen, whole mount. 12. Testis of Locusta migratoria, transversal section. 13. Grasshopper section of testis showing mitosis. 14. Sea urchin developping eggs with divisions, whole mount. 15. Amphioxus transversal section through male and female specimens in region of gonads.