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1. When maintained at an optimum nutritional level both sexes of the South African clawed toad (Xenopus laevis) grow at a normal rate in the complete absence of light, or after removal of the eyes. 2. No detectable atrophic changes take place in the ovaries and testes of eyeless animals after 18 months or in the gonads of male and female toads kept in absolute darkness for 7 months. 3. No evidence is provided by the experiments to show that light is essential for the maintenance of reproductive activity in X. laevis or that seasonal variation in light intensity or wave-length plays any part in the control of the sexual cycle under natural conditions.

Experimental Studies On The Sexual Cycle Of The South African Clawed Toad (Xenopus Laevis). II