(a) The lipolytic activities of human duodenal contents. (b) The separation of the castor bean lipases

Some years ago, Loevenhart 1 showed that extracts of the pancreas and of the liver of various animals contained different lipases. The pancreas extracts exerted greater lipolytic action under comparable conditions toward complex esters such as glyceryl triacetate, and the liver extracts showed greater action toward simple esters such as ethyl butyrate.

During the past year, a number of experiments were carried out on the lipolytic actions of duodenal contents of human beings, both after fasting and after taking food. The Einhorn or the Palefski tube was used to collect the secretions. The behavior was tested, with toluol as antiseptic, toward ethyl butyrate and triacetin under various conditions. The results obtained may be divided into two groups. Greater action toward ethyl butyrate than toward triacetin was observed when no food had been taken for at least twelve hours and the pancreatic juice therefore probably absent. Very much greater action toward triacetin than toward ethyl butyrate was observed in the cases in which food had been taken and the pancreatic juice was present. These relations were observed in a number of cases, but in several cases exceptional results were obtained. Under apparently normal conditions of digestion, when the activity should have been that of the pancreatic juice, that is, very large toward triacetin, a greater action toward ethyl butyrate was observed. Also, when pancreatic juice was expected to be absent, the activity observed in several cases was similar to that observed when it was present. Since, however, relatively few of these cases were observed, the greater activity toward triacetin of duodenal contents containing pancreatic juice, and the greater activity toward ethyl butyrate of contents without pancreatic juice, may for the present therefore be looked upon as the normal.