Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.

different morbid states : the one is neuralgic sensibility, the other is the pain and tenderness of an inflammation. Being thus widely different in their nature, they require a widely dif- ferent treatment. The correct diagnosis of the two conditions, and a true esti- mate of the value of the given pain and tenderness, as leading symptoms, are of the very first importance. The seat of neural- gic pain is frequently in the termination twigs; but that is rarely the seat of the cause. It is to the trunk of the nerve, or to the sensory tract of the cerebro-spinal axis, that we must look for this. In the pain of inflammation, the cause is local; and when it is external there are tumor and rubor. The morbid con- dition, giving rise to hyperesthesia, may be seated in the nerve fibril, or in the central axis ; and it may be either primary or secondary. Any cause which exalts the sensorial function in either point, gives rise to hyperesthesia, as a mechanical injury or contact, or congestion of the neurine. Nerves of sensation passing through foramina in the bones, or winding around bones, or tendons, are peculiarly liable to the first-mentioned causes. Hence the nerves of the face are so much more frequently neu- ralgic than others. Spicula of bone, or of cartilage, or analogous deposits in or on the scro-fibrous envelope of the spinal cord, are of this character. With regard to other causes of hyperes- thesia, the most frequent, and most important, is a propagation of irritation from the peripheral twigs to the central axis; then a diffusion of that irritation through the gray or white matter, so that it then involves other nerve fibrils, and a consequent ex- tension of the pain and tenderness to other sensory nerves. We thus explain the pains experienced in the hips and thighs from congestion of the uterus. This transmission and diffusion of irritation may be from contiguity, as in the case just mentioned, or from functional connection, as between the mamma? and ovaria, or uterus; or the sympathy may arise between parts de- riving their innervation from a common system of nerves, as the uterus and stomach. Hence the anatomical and physiologi- cal relations of the organs affected must enter largely into our consideration, when -establishing the diagnosis between neuralgic and inflammatory pain and tenderness.