This paper treats of blood-pressure, work done recently under the direction of Dr. H. D. Singer, at the State Psychopathic Institute, in cases of mania, depression and agitation. The sphygmomanometer used was that of Erlanger. The number of cases investigated is not large, neither do the extremely-marked examples of mania or agitation figure among those cited because it is impossible to get a reading in such cases. The reason is that as one is dealing with a delicate and sensitive machine which registers blood-pressure graphically, the procedure would probably result in disaster and the reading be worthless. When the typical is sifted out and the impossible is eliminated, surprisingly few cases are left to be dealt with. These few cases, then, were taken without regard to the age of the patient or to the condition of the vascular system; the readings were all taken at regular intervals and at the