Food Absorption 119 



normally, they are given an opportunity to develop with 

 unusual activity and cause bloat, colic and offensive 

 odors in the solid excrement. 



ABSORPTION OF THE FOOD 



From the time the food enters the stomach, during 

 nearly its entire course along the alimentary canal, there 

 is a constant production' of soluble compounds, which 

 progressively disappear into other channels, so that when 

 the anus is reached, only a portion of the original dry 

 matter is found in the residue. In some way, not wholly 

 explainable in all its details, the digested food has been 

 absorbed and received into vessels through which it is 

 distributed to the various parts of the body. 



A merely casual observation shows us that the inner 

 surface of the walls of the digestive organs are covered 

 by numerous projections. The anatomist, by a careful 

 study of these, has learned that imbedded in their tis- 

 sue, especially in the intestines, are the minute branches 

 of two systems of vessels. One set is the lacteals be- 

 longing to the so-called lymphatic system and the other 

 set is the capillaries of the blood system. The lym- 

 phatic vessels or tubes all lead to a main tube or reser- 

 voir, the thoracic duct, which extends along the spinal 

 column and finally enters one of the main blood-vessels. 

 Any material, therefore, taken up by the lacteals ulti- 

 mately reaches the blood. The capillaries all converge 

 to a larger blood-vessel, known as the portal vein, which 

 enters the liver, carrying with it whatever material the 

 capillaries have absorbed. 



