Cvii. on the Physiological Action

THE biochemical action of i-ascorbic acid has hitherto been studied principally on the scorbutic guinea-pig. Only recently Harris et al. [1933] investigated the excretion of ascorbic acid in the human subject and found that with a normal intake of vitamin C about 30 mg. of ascorbic acid can be determined by dichlorophenolindophenol titration in the daily output of urine. The excretion is temporarily increased when large doses of vitamin C (150 ml. lemon juice corresponding to about 150 mg. of ascorbic acid are given). It was also found by van Eekelen et al. [1933] that with a normal diet about 25 mg. of ascorbic acid are excreted daily in the urine. In order to determine if, as in the case of vitamins A and D, symptoms of hypervitaminosis occur after the administration of large quantities of ascorbic acid, the present author has investigated the tolerance of various laboratory animals (cold and warm blooded). The vitamin was administered per os, subcutaneously, intraperitoneally and intravenously, using an aqueous solution of ascorbic acid which was neutralised with sodium hydroxide shortly before use. In the following table the maximum single doses given to the various animals are summarised. Dosage in g./kg.