1. Alpatov, W. W. and Pearl, R. (1929) Amer. Nat.
63, 37–67.
2. Anxolabéhère, D. and Périquet, G. (1970) Bull. Soc. Zool. Fr.
95, 61–70.
3. Baumann, P. A. (1969) Z. Vergl. Physiol.
64, 212–242.
4. Baumann, P. A. and Chen, P. S. (1968) Rev. Suisse Zool.
75, 1051–1055.
5. Bowler, K. and Hollingsworth, M. J. (1966) Exp. Gerontol.
2, 1–8.