‘The sensitiveness of the telephone is indeed exquisite. We see how much it exceeds that of the galvanoscopic frog’s leg, and I have thought of employing it as a galvanoscope. It is very difficult to study the muscular and nervous currents with a galvanometer of 30,000 turns, because the instrument is deficient in instantaneous action, and the needle, on account of its inertia, cannot display the rapid succession of electric variations, such as are effected, for example, in a muscle thrown into electric convulsion. The telephone is free from this inconvenience, and it responds by vibration to each electric change, however rapid it may be. The instrument is therefore well adapted for the study of electric tetanus in the muscle. It is certain that the muscular current will excite the telephone, since this current excites the nerve, which is less sensitive than the telephone. But for this purpose some special arrangement of the instrument is required. ‘It is true that the telephone can only reveal the variations of an electric current, however faint they may be; but I have been able, by the use of a very simple expedient, to reveal by its means the presence of a continuous current, also of extreme faintness. I send the current in question into the telephone, and, to obtain its variations, I break this current mechanically with a tuning-fork. If no current is traversing the telephone, it remains silent. If, on the other hand, the faintest current exists, the telephone vibrates in unison with the tuning-fork.’ Professor Eick, of Wurzburg, has also used the telephone for physiological researches, but in a direction precisely opposite to that explored by M. d’Arsonval. He ascertained that when the nerves of a frog were placed in connection with a telephone, they were forcibly contracted when anyone was speaking into the instrument, and the force of the contractions chiefly depended on the words pronounced. For instance, the vowels _a_, _e_, _i_ produced hardly any effect, while _o_ and especially _u_ caused a very strong contraction. The words _Liege still_, pronounced in a loud voice, only produced a faint movement, while the word _Tucker_, even when spoken in a low voice, strongly agitated the frog. These experiments, reminding us of those by Galvani, were necessarily based on the effects produced by the induced currents developed in the telephone, and they show that if this instrument is a more sensitive galvanoscope than the nerve of a frog, the latter is more susceptible than the most perfect galvanometer.