Page:Popular Science Monthly Volume 83.djvu/426

422 digestion through a fistula following a gunshot wound in the case of the Canadian Alexis Saint Martin, the results being published in 1833, These observations constituted an important contribution to the subject and attracted world-wide attention.

Leuchs in 1831 discovered the starch-digesting properties of saliva. Payen and Persoz in 1833 discovered and studied the amylolytic ferment diastase in germinating barley. Mialhe in 1845 isolated ptyalin from saliva.

J. N. Eberle in a work published in 1834 was the first to note the power of an extract or artificial gastric juice prepared from the gastric mucous membrane to dissolve proteid material. He, however, erroneously attributed this solvent action to the mucus on the surface of the stomach. Theodor Schwann (1810-1882), the discoverer of animal cells, investigated the subject (partly in association with his teacher Johannes Müller) and in crude form isolated from the gastric mucosa a principle possessing intense proteolytic powers, to which he gave the name pepsin; his results were published in 1836.

In his treatise published in 1834 Eberle noted the fact that a watery extract of the pancreas would emulsify oil, and he surmised that one of the functions of the pancreatic secretion was to favor the absorption of fat. In 1836 Purkinje and Pappenheim discovered that extracts from the pancreas possess proteolytic properties. In 1844 Valentin made some observations on the starch-digesting powers of the pancreatic fluid; and in 1845 Bouchardat and Sandras definitely demonstrated the secretion of an amylolytic principle by this organ.

Following these pioneer discoveries, the elucidation of the functions of the pancreas, especially its fat-splitting action, was accomplished chiefly by the work of the French investigator Claude Bernard (1813-1878), whose researches on this subject were prosecuted about 1836-1846.

From these beginnings the chemistry and physiology of digestion have been further elaborated by numerous subsequent investigators.

The study of gastric digestion was made a simple clinical procedure by the employment of the stomach tube for obtaining samples of gastric juice. This originated with Adolph Kussmaul (1822-1902), who in 1869 reported the use of the stomach tube in the treatment of dilatation of the stomach; subsequent to which the examination of gastric juice for diagnostic purposes was elaborated by W. O. Leube, C. A. Ewald and Franz Riegel, and their associates during the seventies and eighties of the last century.

Important studies of the action of the digestive organs were not long ago made by Ivan Pyotrovich Pavloff (often transliterated, from the German, J. P. Pawlow) (born 1849), director of the Imperial Institute of Experimental Medicine in Saint Petersburg, the results of whose brilliant researches (conducted 1887-1897) were first published in