A simple and very old means to demonstrate and to record the properties of either an isolated nerve and/or the pertinent muscle, actually introduced by Galvani. It consists of the thigh bone (femur) of a frog, without the muscles, the shank cut down to a stump, and only the musculus plantaris longus, main portion of the calf, left to it, and with it the nervus ischiadicus (actually all nerves coming out of the vertebral canal and running to the legs, hence actually the entire plexus ischiadicus). The femur serves to fasten one end of the preparation to the recording device, the other end consists of the aponeurosis plantaris, the foot tendon, which serves to fasten a hook to connect the preparation to a lever or, most simply, to a little bell. Whenever the muscles starts to twitch the bell rings, providing an acoustical signal to the experimenter, that the preparation works. When preparing, the nerve plexus is tied to a thread to avoid touching the nerve tissue which may hurt it. The plexus then is removed from the pelvis and taken out of the thigh muscles, but still remains into contact with the calf muscle. The nerve plexus becomes connected to the electrodes of a stimulator of whatever kind. Galvani used a bimetal rod to cause a twitch of the muscle, today more sophisticated implements are used. The proof that Mormyridae do have a true electric organ - and not pseudo-electric organs - was also made by a means of a nerve-muscle preparation by either putting the ischiadicus on the organ or by connecting the tank of a Mormyrus by some wires to the nerve. (Babuchin, Fritsch).