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

while a current of equal or greater strength, directed in precisely the same manner through the muscles themselves, shows no sign of contraction. If, now, we place one electrode on the muscle and the other electrode on the nerve trunk, then the lifting up of the latter electrode will produce contraction, while the lifting up of the other will leave the muscle still at rest; and this dif- ference between the two will be the greater, the more care we take to produce waving or staggering of the current, just as the electrode is leaving the skin. " Alternations of Ritter " may be understood by placing the two electrodes, say the one on the nerve medianits, and the other over the nerve raclialis, in the neighborhood of the bend of the elbow where those nerves come nearest the skin, and then make contact from a battery of some thirty to fifty Daniell's elements, for there will appear, as a general thing, im- mediate contraction for flexion, which may also last while the current runs, producing a fair bending of the arm from the ac- tion of the flexors. Sometimes, however, this appears rather in the extensors. But if the direction of the same current is now reversed by means of the metallic key of the key-board, and that while the electrodes remain as they were upon the same spots, then the previous contraction, after a momentary recess occasioned by the turning of the current, appeal's again, (and now with increased strength,') or even will show it in the antago- nizing muscle groups. Now, in case this latter result obtains, if the current direction be changed again very suddenly, as before, then the previous contraction comes in again, and this "al- ternation " appears so much the more readily in proportion to the suddenness and frequency of the changed directions of the current. Occasionally these results do not appear until after the changing has been repeated several times. Sometimes, moreover, these alternations of the current are attended with contraction of the flexors from the up-running current, while the down-running current produces contraction in the extensors; and this order of events follows the regular turnings of the current. Labile icorkings of primary, and also of secondary elec-