. The clinical study of blood-pressure : a guide to the use of the sphygmomanometer in medical, surgical, and obstetrical practice, with a summary of the experimental and clinical facts relating to the blood-pressure in health and in disease . The fall ofblood-pressure which followsstrong stimulation of the vagiperipherally is produced byboth slowing the heart anddecreasing the systohc output;and the two most commonly coincide. Such a fall in pressure,with marked decrease in ventricular output and slowing of theheart, is beautifully illustrated by a tracing of Porters * froman experiment, in w
. The clinical study of blood-pressure : a guide to the use of the sphygmomanometer in medical, surgical, and obstetrical practice, with a summary of the experimental and clinical facts relating to the blood-pressure in health and in disease . The fall ofblood-pressure which followsstrong stimulation of the vagiperipherally is produced byboth slowing the heart anddecreasing the systohc output;and the two most commonly coincide. Such a fall in pressure,with marked decrease in ventricular output and slowing of theheart, is beautifully illustrated by a tracing of Porters * froman experiment, in which the diminished cardiac energy fol-lowed tying off the circumflex branch of the coronary arteryin a dog. Rate and volume do not necessarily follow one another,however, for both Woolridge ^ and Pawlow, by the stimulation 1 Porter, W. T. Further Researches on the Closure of the Coronary Arte-ries. Journal of Exper. Med., 1896, vol. i, p. 51; also, Amer. Text-Book ofPhysiol., second edition, 1900, vol. i, p. 183. Woolridge, Leonard. Ueber die Function der Kammernerven des Sailge-thierherzens. Arch. f. Anatomic u. Physiologic, Abtheilung f. Physiologic,1883, p. 587. Pawlow, I. P. Ueber d^n Binfluss des Vagus auf die Arbeit der linkcn. Fig. 3.—Fall in blood-peessuee peo-duced by stimulation of the peeipii-eeal cut end of the vagus. Trace from dogs carotid. Tetaiiizing cur-rent. FACTORS DETERMINING BLOOD-PRESSURE 13 of certain augmentor nerve branches in dogs, obtained increasein pulse volume and rise in pressure without change in fre-quency. This vsras probably due to greater suddenness of con-traction, allowing a longer diastohc period for the filling of theventricle. Vice-versa, increased rate does not always raisepressure. Miinzel demonstrated this most clearly. Havingfirst severed the spinal cord to ehminate all vaso-motor influ-ences, he stimulated the accelerator nerve and, in spite of theextreme rise in rate, the change in pressure was greater frequenc
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