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

after the current was made to traverse the nerve radialis super- ficialis,— which is a sentient nerve branch, — near to the radial artery, there is then occasionally produced an extension of the hand; and yet this effect is not apparent when the electrode is not on, or is removed rather to the one side of that nerve, even if but a trifle. Such results obtained as pre-trials on man were then followed by the following trials and deductions: first, a current run- ning in a downward direction through the nerve radialis superficial is, produced the extension of the hand; when the cur- rent was turned so as to run upward through the same nerve, there was closure of the hand. In another person, in health, it was observed that when the current traversed the nerve media- nus downward, there was pain, with tonic extension of the hand; but when turned to run upward in the same nerve, there was less pain, but now tonic flexion. Thus it seems, says Eemak, that no other explanation remained than this: that these tonic contractions were really called in play by a central excitement, which itself was caused by the action of the current on the sen- tient nerves; and that all those variations and differences ob- served in isolated cases arose from central variations mostly, but also in some degree from the variations in the susceptibility of the sentient nerves along the extent of their ramification — " in a word, this is none other but a true reflex-action.'''' In 1858, he made other trials, and having already had much experience in the medical uses of electricity, both by primary, constant currents, (i. e., seldom broken,) and by interrupted induction currents, he seems to be confirmed in the opinion of the main, central source of these contractions. He cites the case of a woman who had long suffered from hemiplegia, in whom he succeeded in producing tonic contractions of the paralyzed ex- tensor muscles of the arm, by means of the so-called constant galvanic current coursing through the nerve cruralis and its branches, on the praralyzed side. The following trial, I think, is a very instructive one. If we take even a sensitive frog thigh, prepared after Galvani's method, and lead the current ou to the nerve or muscles, not by means 26 *