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

the paralysis, or spasmo-paralysis, so induced, is less persistent than in the latter case. " This remark leads me to the subject of the excito-motor pow- er itself, on which all the movements connected with the spinal system depend. This power may be diminished or even sus- pended in its energies; it may be also greatly augmented; in which case there is proportionate susceptibility to impressions, and to excited actions the results of those impressions. " The former state of things is induced by all agents of such violent character as produce shock; the latter is induced by peculiar agents, of a chemical or physical character, which act more gently on the nervous structures. The same identical agent may produce either of these effects, indeed, according to its degree. Thus too large a dose of strychnine speedily de- stroys all excitability; a very minute dose, on the contrary, induces the most extraordinary phenomena of augmented ex- citability which wc can witness. The action of the electric cur- rent is precisely similar; a very mild current produces purely physiological effects; too strong a current soon induces destruc- tion of the excitability of this part of the nervous system. The first effect of decapitation (of shock) in a frog, is supension of the excito-motor power; the second and ulterior effect is, or is supposed to be, an augmented susceptibility to activity of this vital agent. Electricity, heat, and the class of agents called stimuli, generally, may be employed so as to act as augmentative or destructive of the excito-motor nervous power. " As an example of these effects, I may mention, for the benefit of those who have not performed an experiment, that immedi- ately after decapitation of the frog, no reflex actions arc pro- duced, on irritating the foot; it is here diminished excitability, the effect of shock. On administering a minute dose of strych- nine, on the contrary, the touch even of a feather induces reflex action of a tetanic force and character. " From experiments we learn that this augmented susceptibility or excitability may exist in force, without existing in action. A frog may be under the influence of strychnine, yet, if not actually excited, it may remain quiescent, relaxed in posture; it is tutau-