Summary.If atropine sulphate, in doses of 0.2 g/kg, is given subcutaneously to mice, previously treated with iminodipropionitrile and showing “waltzing syndrome” with pronounced hyperactivity and compulsive, circling movements, these symptoms are greatly reduced. The effect of atropine generally lasts 3—6 hours; after 24 hours full hyperactivity has returned. The effect of atropine can then be rep