Hydrocortisone in doses as low as 2.5 mg. per day (approximately 1.0 mg. per kg. per day) markedly depressed antibody production whereas corticosterone in doses four times as large exerted no significant effect.

Corticotropin in doses of 15 units daily exerted an effect similar to that of corticosterone, but its effect was more like that of hydrocortisone when given in doses twice as great. This finding is in agreement with observations that the prolonged administration of corticotropin in sufficient dosage leads to increased output of hydrocortisone by the adrenal cortex of the rabbit.

Corticosterone did not antagonize the effect of hydrocortisone on antibody production, but seemed to act additively with it.

Although each of the hormones tested induced some adverse effect on nitrogen balance as measured by the weights of the animals, and hydrocortisone induced the more striking decreases in weight, there was no direct correlation between the effects of these hormones on antibody production and their effects on weight.