Chylifaction, or the formation of chyle, is the next great step in the process of digestion. This takes place in the duodenum. The chyme from the stomach is let into this intestine little by little. A valve at the lower opening or outlet of the stomach prevents it from passing any faster than it can be disposed of in the formation of chyle. This fluid is a thin milky liquid extracted from the chyme, and then taken up by absorbent vessels, called lacteals.

The chyme passes slowly through the duodenum; and in doing so, becomes mixed with another fluid furnished from the pancreas or sweet-bread, and the bile from the liver. Pass ing thus slowly through this large intestine, ample time is given for the lacteals to take up all that is valuable to be carried into the circulation for the nourishment and support of the system. This chyle, taken up by the lacteals, is directly converted into blood; and in many of its characteristics it very closely resembles blood. The process by which this conversion is carried on, is called absorption. That class of absorbent vessels called lacteals are not only found in the first intestine, or duodenum, but are distributed along the small intestines, for the purpose, as before stated, of conducting the chyle in its appropriate course for the formation of blood.