1. The favourable influence of the clinical symptoms of Parkinson syndrome by harmine is confirmed. 2. Harmine causes an increase in the excitability of the vestibular apparatus both in normal human and post-scephalitic parkinsonism. 3. The lowering of blood pressure and bradycardia that trigger the harmine are the expression of an increase in excitability of sinus caroticus. The harmine sensitizes all reflections of the sinus caroticus. 4. The vascular reflections (oculo-vascular reflection, colder-irritation reflection, vasomotor reflection of arbitrary contraction) which have an abnormal course in the Parkinson syndrome are favourably influenced by the harmine. 5. Harmin dampens the overexcitability of the parasympathic system with sick suffering from post-encephalitic parkinsonism and increases the underexcitability of the sympathetic system. 6. On the isolated frog heart, the harmine exerts a diastolic vagal effect, and this is eliminated by the calcium ion. 7. Harmine has the tendency to return the pathological chronaxies of nerves and muscles in Parkinson syndrome to their normal values, but to a smaller extent than scopolamine. 8. On the isolated nerve muscle preparation of the frog, harmine causes a decrease in muscle and nerve chronaxia. The decrease in chronaxia of muscle is much greater than the decrease in nerve chronaxia.