Sensitivity of mice to histamine was estimated with the death-rate by its subcutaneous injection. In control group without bath ten mg. of histamine per ten g. of body weight
proved to be tolerable, but twenty mg. of histamine per ten g. of body weight was lethal in August. To 24 mice were given everyday a plain water bath at 37℃ for ten minutes. To another 24 mice were given everyday a thermal bath of Misasa at 37℃for ten minutes. On the 4th, 7th, 14th and 21st day to each six mice of both groups was given a subcutaneous injection of histamine, namely to three mice was given ten mg. of histamine per ten g. of bodyweight and to another three mice was given twenty mg. of histamine per ten g. of body weight. In plain water bath group no change in death rate was shown during the series of bath days. But in the thermal bath group a 100% 1ethality was recognized on the 4th day, 67% lethality was proved on the 7th day and only 17% lethality was shown on the 14th day. Histamine or histaminelike substance is known to be a chemical agent liberated in
the skin by any skin irritants. And the above-mentioned change in the sensitivity to histamine during a series of
thermal baths suggests an explanation to the mechanism of thermal crisis that has a tendency to occur in the first week of thermal bath cure.