46 HUMAN PHYSIOLOGY 



we have the absorption into the blood of certain 

 highly important articles of food. It would al- 

 most seem as if nature taught us the lesson that 

 the nitrogenous foods required for body-building 

 purposes are of high importance, and, as such, have 

 to be more readily and quickly passed into the 

 circulation; the starches, fats, and sugars, on the 

 other hand being less important, and requiring to 

 wait for digestion in the bowel or intestine. The 

 stomach may be regarded in this sense as a kind of 

 half-way house on the digestive journey in which the 

 progress of the food is for the time being arrested 

 in order that the nitrogenous foods converted into 

 peptones should be passed onwards into the liver, 

 there to be further dealt with and fitted for their 

 ultimate destination, namely the blood current. 



THE LIVER. The third stage of the digestive 

 journey may be said to commence with the passage 

 of the food from the stomach into the intestine or 

 bowel. Immediately the food enters this portion of 

 the digestive tube it meets with bile from the liver 

 (Fig. 11) and sweetbread juice from the pancreas or 

 sweetbread. These two secretions are poured upon 

 the food practically at the same point, the duct or 

 tube from the sweetbread frequently joining that 

 coming from the liver. The liver is the largest 

 organ of the body, weighing between three and four 

 pounds, and lying to the right of the stomach shel- 

 tered beneath the lower ribs of that side. Essentially 

 the liver is a great colony of "hepatic" or liver cells, 

 the diameter of each cell averaging the 1-1, 000th 

 part of an inch. Into the liver there passes from 

 the great portal vein already mentioned, a continu- 

 ous supply of blood returned from the digestive 

 organs at large. This blood, as we shall see, is laden 



