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 blood; it is an excretion. Although an excretion, it is of use on its way out of the body. It is alkaline and helps to neutralize the acid in the chyme; it excites the peristalsis, or wavelike motion, of the intestines, and it aids the pancreatic juice to emulsify the fats.

to show the many folds of the supporting the liver, stomach, and intestines.

The large intestine, or colon, is about two and one half inches in diameter and five feet long. The small intestine joins it in the lower right side of the abdomen (Fig. 90). There is a fold, or valve, at the juncture, and just below the juncture there is a tube attached to the large intestine, called the appendix, which sometimes becomes inflamed, causing a disease called appendicitis (Figs. 90, 98). The appendix is a vestigial (vestigium, trace) or rudimentary organ, long since useless. Absorption of the watery part of the food continues in the colon, but the colon secretes no digestive fluid. The undigested and innutritious parts of the food are regularly cast out of the colon. The peritone'um is a membrane with many folds that supports the food tube (Fig. 99).

Absorption.—The way in which the various digested foods are absorbed has been stated in several preceding topics. What is the name of the organs of absorption in the small intestine? Which of the following pass into the lacteals, and which into the capillaries of the portal vein: sugar, digested proteid, emulsified fats? Water and salt need no digestion, and are absorbed all along the food