We have seen that if we send a shock of electricity through a motor nerve the nerve becomes excited, and responds by contraction of its muscles. One form of electricity, then, is a stimulant, but, unlike other stimulants, it admits of its action being exactly localized and its influence instantly withdrawn. [SN: Effects upon Nutrition.] There first results from such an application a larger flow of blood to the part, with subsequent increase of temperature and general improvement in nutrition. [SN: Electricity as a Stimulant.] If muscular contraction results, it acts in addition as an artificial gymnast, imitating natural muscular action in a way quite impossible to any agency but electricity. It is in cases where there is muscular response to it, but not to the will, that it is often of immense service, and it can then be replaced by no other remedy known to medicine. Need I say that in such cases its dosage is of importance; that only a certain amount of stimulation being needed, this may not be carried to the point of exhaustion, and that the application should not be continued for too long a time. From ten to twenty minutes for an entire application is usually sufficient. So much for the stimulant effects of electricity when administered under either of its forms in a series of intermittent “shocks.” [SN: The Constant Current.] But we get a very different result when we employ a constant current--that is, a continuous stream of electricity without interruption or break in it, and without appreciable variation in its strength. One effect of the administration of such a flow of electricity is that of a sedative, for it possesses the most remarkable power in relieving pain. We have all heard of the benefit of the “constant current” in neuralgia, and it is worthy of its reputation, and will not disappoint us if we administer it with the precautions noted in my last Lecture. (See foot-note, page 52.)[16] [SN: Electricity possesses an influence _sui generis_.]