Abstract
1. All control rats with a total vitamin A-deficiency die within two weeks after an suspension of increase in the body weight. 2. Daily administrations of less than 3 I.U. of either natural or synthetic vitamin A oil do not prevent the death of animals. When 3 I.U. are given, the animals recover, no marked difference in effect being found between the two oils. But the growing curves increase steeper with the natural than with the synthetic oil. 3. Within the physiological doses, the rate of recovery increases proportionally to the amounts of administration. It varies almost proportionally to the values observed by the Beckman's spectrophotometer.
