Experimental physiology / by Sir Edward Sharpey-Schafer.

  • Sharpey-Schäfer, E. A. (Edward Albert), Sir, 1850-1935.
Date:
1927
Catalogue details

Licence: In copyright

Credit: Experimental physiology / by Sir Edward Sharpey-Schafer. Source: Wellcome Collection.

    41/156 (page 29)
    Thermal excitation.—A nerve (or muscle) is stimulated if touched with a hot wire; or with a wire cooled to below 0° C. Osmotic excitation.—A nerve can be stimulated by withdrawal of water, caused by placing brine or glycerine upon it. The salt and the glycerine both act by abstracting water. Excitation by drying.—The withdrawal of water by drying also acts as a stimulus to nerve. When the nerve begins to dry, its muscle twitches.1 Addition of water may also act as a stimulus, especially with muscle. If distilled water is injected into the blood-vessels of an animal, all the muscles are thrown into contraction : this is, however, followed by paralysis. The effect is in part due to the abstraction of calcium salts from the muscle. 1 This twitching is a frequent source of puzzle to the beginner ; it is always a sio-n that he has not been careful to keep the nerve moist.