A review of the literature on the physiology of the large intestine and our own experience indicate that this organ is valuable, although not indispensable to the human economy. One of its interesting functions is the secretion of mucus. In a previous paper, the work of Hay, Luciani,1 Voit, Carpenter and Goldsworthy and Florey2 has been mentioned. In an excellent review, along with some work of his own, Heupke3 summarized the present knowledge of the secretion and excretion of the colon. Using a Thiry-Vella type of fistula in a dog, he found the quantity of secretion from the colon to be rather small; this was not due to resorption of the secreted fluid, because by invagination of the isolated portion in a certain way the material could drop off as it formed. No difference in amount was noted from that ordinarily obtained by irrigating the segment. He