104 THE HOME, FARM AND Bl'SIXKSS CYCLOPEDIA. 



In the duodenum, the chyme becomes intimately mixed and incorporated 

 with the bile and pancreatic juice ; also with a fluid secreted by the mu- 

 cous follicles of the intestine itself. The bile is a greenish, bitter, and 

 somewhat viscid fluid, secreted by the liver, which occupies a considerable 

 space on the right side of the body, immediately under the ribs. From this 

 organ the bile, after a portion of it has passed up into the adjacent gall- 

 bladder, descends through a small duct, about the size of a goose-quill, into- 

 the duodenum. The chyme, when mixed with these fluids, undergoes a 

 change in its appearance ; it assumes a yellow colour and bitter taste, 

 owing to the predominance of the bile in the mass ; but its character varies 

 according to the nature of the food that has been taken. Fatty matters, 

 tendons, cartilages, white of eggs, etc., are not so readily converted into 

 chyme as fibrous or fleshy, cheesy, and glutinous substances. The chyme, 

 having undergone the changes adverted to, is urged by the peristaltic mo- 

 tion of the intestines onward through the alimentary canal. This curious 

 motion of the intestines is caused by the contraction of the muscular coat 

 which enters into their structure, and one of the principal uses ascribed to 

 the bile is that of stimulating them to this motion. If the peristaltic motion 

 be diminished, owing to a deficiency of bile, then the progress of digestion is 

 retarded, and the body becomes constipated. In such cases, calomel, the 

 blue pill, and other medicines, are administered for the purpose of stimu- 

 lating the liver to secrete the biliary fluid that it may quicken by its stim- 

 ulating properties the peristaltic action. But this is not the only use of 

 the bile : it also assists in separating the nutritious from the non-nutritious 

 portion of the alimentary mass, for the chyme now presents a mixture of 

 a fluid termed chyle, which is in reality the nutritious portion eliminated 

 from the food. The chyme thus mixed with chyle arrives in the small in- 

 testines, on the walls of which a series of exquisitely delicate vessels ram- 

 ify in every direction. These vessels absorb or take up the chyle, leaving 

 the rest of the mass to be ejected from the body. The chyle, thus taken- 

 up, is carried into little bodies of glands, where it is still further elaborated, 

 acquiring additional nutritious properties ; after which, corresponding ves- 

 sels, emerging from these glands, carry along the fluid to a comparatively 

 large vessel, called the thoracic duct, which ascends in the abdomen along 

 the side of the back-bone, and pours it into that side of the heart to which 

 the blood that has already circulated through the body returns. Here the 

 chyle is intimately mixed with the blood, which fluid is now propelled 

 into the lungs, where it undergoes, from being exposed to the action of the 

 air we breathe, the changes necessary to render it again fit for circulation. 

 It is in the lungs, therefore, that the process of digestion is completed ; the 



