The experimental method in medical science : second course of the Cartwright Lectures of the Alumni Association, College of Physicians and Surgeons, New York delivered January 24, January 31, and February 7, 1882 / by John C. Dalton.

  • Dalton, John Call, 1825-1889.
Date:
1882
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Licence: Public Domain Mark

Credit: The experimental method in medical science : second course of the Cartwright Lectures of the Alumni Association, College of Physicians and Surgeons, New York delivered January 24, January 31, and February 7, 1882 / by John C. Dalton. Source: Wellcome Collection.

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    vessels, and so reduces the volume of the circulating blood. The knowledge of these facts introduced into the nomen- clature of the nervous system a new title. There were evidently nerve-fibres which acted upon the blood-vessels to call into operation their contractile power; and the nerves possessing such a function, then known for the first time, naturally received the name of the “vaso-motor nerves.” But, in following out this subject, an observation was soon met with of very unexpected character; namely, that certain other nerves, on being stimulated, instead of pro- ducing contraction of the blood-vessels, caused their relaxa- tion, and thus increased the activity of the circulation. This was first shown by Bernard in the case of the sub- maxillary gland. This organ is supplied with sympathetic fibres from the superior cervical ganglion and the carotid plexus, and with cerebro-spinal fibres from the lingual nerve and the chorda tympani. Galvanization of its sympathetic filaments produces, as in other similar instances, contrac- tion of the vessels, and a diminished blood-supply. But if the stimulus be applied to the lingual nerve above the situation of the gland, or to the chorda tympani, which unites with it, the result is exactly the contrary; the blood-vessels enlarge and the circulation is more active so long as the galvanization continues; and this effect is equally marked if the nerve be divided, and galvanized between its point of section ,and the gland. A similar influence was found to reside in other parts of the nervous system; and the nerves possessing the power of thus causing vascular enlargement were called “dilator nerves.” No sooner was this fact established in a general way, than it served to explain a singular phenomenon which had been noticed many years before, but which had thus