a)The author studied the changes in the activity of choline'-esterase (ChE) in serum, before and after a radio-active thermal bath (43℃,5min.)in Misasa, and their seasonal differences. The results were as follows: (1) The ChE activity in human serum was stronger in winter than in summer. (2) The ChE activity was reduced after the thermal bath, and the decrease was more marked in winter than in summer. b) The author proved by Laewen-Trendelenburg's method that fresh radio-active thermal water of "Yamada-Ku-Kyodo-Yu" in Misasa dilatates the blood-vessel, but the same water, stored for weeks, constricts the vessel. Under the author's experimental conditions the dilatating effect of the radio-active spring waters proved to become stronger as their radon content increases. The freshly taken Yamada-Yu water inhihited the action of Adrenaline or Imidaline (a benzyl-imidazoline derivate), but the aged Yamada-Yu water showed no such antagonistic action. c) Blood circulation time, measured with vitamine B(1), was reduced after the thermal bath, but the changes showed no significant difference between the radio-active thermal bath and plain water bath. d) The height of waves of the electrocardiograms in healthy persons increased more after
the radio-active thermal bath than after the plain water bath in general. The increase was higher as the temperature of bath rises, but the difference between the kinds of baths was not significant. In chronic rheumatism and hypertension patients the increase was slight, and in some cases a remarkable fall of ST was recognized after the radio-active thermal bath at 40℃ for 10 minutes. QRS shortened slightly in Wilson's lead. After a bath at 40℃ for 10min., lowering of the minimal blood pressure was not so marked than after a bath at 43℃ for 5min., both in healthy and diseased persons.