During the first stages of digestion in the cat’s small intestine the food usually lies chiefly on the right side of the abdomen; during the last stages the loops on the left side contain the greater amount of food. In these loops the food remains sometimes for an hour or more with no sign of movement. All at once a mass begins to show irregular depressions and elevations along its length, and then suddenly it is divided, at first partially, later completely, into many little equal parts, and these repeatedly undergo division and reunion, division and reunion, over and over again, in the manner described above as rhythmic segmentation. After a varying length of time the activity wanes and the little segments are carried forward individually and later brought together, or join and move on as a single body, or they may reunite and lie quietly for some time without further change. Thus by a combined process of kneading and peristaltic advance the food is brought to the ileocæcal valve to enter the large intestine. Records from ten different animals show that salmon does not appear in the small intestine until an hour or an hour and a half after the food is eaten. Inasmuch as five or six hours elapse after eating before this food begins to be seen in the colon, it is evident that the chyme takes four to five hours to pass the length of the small intestine. It is interesting to note that the operations are considerably shortened if the meal has consisted of bread and milk. THE COMPETENCE OF THE ILEOCÆCAL VALVE The ileocæcal valve in the cat is situated three or four centimetres from the blind end of the cæcum. Its position is usually marked in shadows of the food in the colon by a slight indentation, towards which masses about to enter the colon are ordinarily directed from a point somewhat distant in the small intestine (see Fig. 6). Regarding the competence of the ileocæcal valve many observations have been made. Grützner has reviewed the evidence bearing on the question and concludes that the valve is not competent, least of all for liquids. He declares that as soon as liquids or thin fluid masses appear in the upper part of the colon they pass in many instances into the small intestine the moment that the pressure on the colon side rises slightly. If the colon contains a solid or a thick, mushy mass, the passage towards the small intestine is scarcely possible, because every increase of pressure in the large intestine must force the two lips of the valve together and close it.