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Vit B12or liver extract administered to force-fed rats on constant food intake induced neither weight gain nor N retention. When vit B12was administered to force-fed rats on constant food intake, made hyperthyroid by injection of thyroxine, the weight loss was identical with that of hyperthyroid animals not receiving vit B12. The N loss resulting from the catabolic action of thyroxine, however, was significantly smaller in thyroxine-treated rats receiving B12than in the thyroxine-treated controls. Liver extract had a, similar action, but the values obtained were statistically not significant. These results suggest that in hyperthyroid rats vit B12spares protein at the expense of other body constituents.

A case of marked sensitivity to vitamin D, is discussed. The reason for the occurrence of hypercalcaemic crisis three weeks after the beginning of treatment with 100 000 units of vitamin D is unknown. The possibility that either lack of thyrocalcitonin or synergism with a tumour produced parathormone-like substance played a role in the hypersensitivity to calciferol is suggested. The important but rarely reported electrocardiographic pattern of extreme hypercalcaemia was noted.

In rats receiving a constant food intake by tube feeding, the weight loss and N loss induced by cortisone is not improved by treatment with vit. B12. This failure of vit. B12to influence cortisone induced protein catabolism is in contradistinction to the N sparing effect of vit. B12in thyroxine induced protein catabolism.