It is probable that under normal conditions a fluid is secreted from the entire length of the intestine, but this fluid undoubtedly differs somewhat in the various parts. The duodenum with Brunner’s glands, the jejunum and ileum with the glands of Lieberkühn and the large intestine in which there is a preponderance of mucus cells may be assumed to give secretions which are not identical. The methods which have been used to obtain the succus entericus for analysis are subject to criticism, and much remains to be discovered with regard both to the mechanism of secretion and the nature of the normally secreted fluid. The most fruitful method has been that instituted by Thiry,[12] and later modified by Vella.[13] This consists of the establishment of a permanent fistula from the intestine through the skin from which the intestinal juice may be gathered after complete healing has taken place. This is commonly known as a Thiry-Vella fistula. In general it has been observed that practically no fluid is secreted into the intestine without a stimulus of some sort. Electrical or mechanical stimulation as well as the introduction of food causes a yellowish fluid to pour into the gut. Pregl[14] has studied the secretion by this method in a lamb. Here he finds a continuous secretion which is increased after the taking in of food. It possesses a distinctly alkaline reaction, and contains carbonates, chlorides, and a considerable quantity of proteid. It also contains urea. For a complete analysis the reader is referred to Pregl’s article. The intestinal juice of the lamb has no digestive action on proteids. There was formed from starch paste a fermentable sugar. Cane sugar and maltose were inverted, but milk sugar remained unchanged.