1. Lindh, J., Quantitative Aspects of Prenatal Gonad Growth in Albino Rat and Golden Hamster studied by Morphologic and Experimental Methods (Department of Anatomy, Lund, 1961).
2. Mittwoch, U., Delhanty, J. D. A., and Beck, F., Nature, 224, 1323 (1969).
3. Mittwoch, U., Phil. Trans. Roy. Soc., B, 259, 113 (1970)
4. Beatty, R. A., Phil. Trans. Roy. Soc., B, 259, 3 (1970).
5. Lillie, F. R., Development of the Chick, third ed. (rev. by Hamilton, H. L.) (Holt, New York, 1952).