=Infectious Diseases= In all infectious diseases the blood pressure tends to be lower than normal. During chills the systolic may rise to great height due to the violent muscular contractions. We found the blood pressure of great value in giving information concerning the circulation. Again we repeat that it is not the systolic alone or the diastolic alone but the pulse pressure which we wish to keep informed about. In pneumonia we have tried out Gibson's law only to discard it. This so-called law is that in pneumonia the systolic pressure in millimeters should remain above the figure for the pulse rate. When the figure in mm. of pressure is equalled by or exceeded by the pulse rate the prognosis is grave. In typhoid fever we have made many estimations at various stages of the disease. We can only say that the pressure picture tends to fall during the course. The systolic falls more than the diastolic so that it is not uncommon to see pulse pressures of 20 mm. at the beginning of convalescence in spite of the high caloric feeding practiced. At the time of perforation the systolic pressure may be raised. This is only the reflex from the initial pain. Soon the pressure falls and if peritonitis sets in, the pressure is exceedingly low and the pulse pressure gradually falls until the circulation can no longer be carried on. In large hemorrhage the pressure suddenly falls. If only one hemorrhage has occurred a gradual rise takes place, but the general pressure picture remains at a lower level for days, gradually returning where it was before the hemorrhage. In beginning failure of the circulation we found elevation of the foot of the bed about nine inches to be of such value that we felt there must be some increase in blood pressure. Numerous readings were made covering a period of several months. Although we felt certain that the circulation was improved, we rarely needed cardiac stimulation, we never could prove any increase of blood pressure with the sphygmomanometer. In all infectious diseases there is no help offered by blood pressure estimations in diagnosis. The sole and important use is that of keeping track of the circulation. =Valvular Heart Disease=