They were filled, according to Reaumur's method, with pieces of meat.

After a certain length of time he would have the acrobat disgorge the tubes, and in this way he observed to what degree the process of digestion had taken place.

It was also probably the sword-swallower who showed the physicians to what extent the pharynx could be habituated to contact, and from this resulted the invention of the tube of Faucher, the esophageal sound, ravage of the stomach, and illumination of this organ by electric light.

Some of these individuals also have the faculty of swallowing several pebbles, as large even as hen's eggs, and of disgorging them one by one by simple contractions of the stomach.

From time to time individuals are seen who possess the power of swallowing pebbles, knives, bits of broken glass, etc., and, in fact, there have been recent tricky exhibitionists who claimed to be able to swallow poisons, in large quantities, with impunity.