302 ABSORPTION LYMPH AND CHYLE. 



Of the constituents of the chyle not given in the ordinary analyses, the 

 most important are the urea, which in all probability is derived exclusively 

 from the lymph, and sugar, coming from the saccharine and amylaceous arti- 

 cles of food during digestion. 



The difference in chemical composition between the unmixed lymph and 

 the chyle is illustrated in a comparative examination of these two fluids taken 

 from a donkey. The fluids were collected by Lane, the chyle being taken 

 from the lacteals before reaching the thoracic duct. The animal was killed 

 seven hours after a full meal of oats and beans. The following analyses of 

 the fluids were made by Rees : 



COMPOSITION OF CHYLE AND LYMPH BEFORE REACHING THE THORACIC 



DUCT. 



Chyle. Lymph. 



Water 902-37 965-36 



Albuminous matter 35-16 12-00 



Fibrinous matter 3-70 1-20 



Animal extractive matter soluble in water and alcohol 3-32 2-40 



Animal extractive matter soluble in water only 12-33 13-19 



Fatty matter 36-01 a trace 



G i- ( Alkaline chlorides, sulphates and carbonates, with ) nii 

 oaits, ( i_ . i. j i r "* 



( traces of alkaline phosphates and oxide of iron. 



1,000-00 1,000-00 



The above analyses show a very marked difference in the proportion of 

 solid constituents in the two fluids. The chyle contains about three times as 

 much albumen and fibrin as the lymph, with a larger proportion of salts. 

 The proportion of fatty matters in the chyle is very great, while in the lymph 

 there exists only a trace. The individual constituents of the chyle given in 

 the above tables do not demand any farther consideration than they have 

 already received under the head of lymph. The albuminoid matters are in 

 part derived from the food, and in part from the blood, through the admixt- 

 ure of the chyle with lymph. The fatty matters are derived in greatest part 

 from the food. As far as has been ascertained by analyses of the chyle for 

 salts, this fluid has been found to contain essentially the same inorganic con- 

 stituents as the plasma of the blood. 



The presence of sugar in the chyle was first mentioned by Brande, who 

 described it, however, rather indefinitely. Glucose was first distinctly recog- 

 nized in the chyle by Trommer, and its existence in many of the higher orders 

 of animals has since been fully established by Colin. 



Microscopical Characters of the Chyle. The milky appearance of the 

 chyle as contrasted with the lymph is due to the presence of a large number 

 of very minute fatty granules. The liquid becomes much less opaque when 

 treated with ether, which dissolves many of the fatty particles. In fact, the 

 chyle of the thoracic duct is nothing more than lymph to which an emulsion 

 of fat in a liquid containing albuminoid matters and salts is temporarily 

 added during the process of intestinal absorption. The quantity of fatty 

 granules in the chyle varies considerably with the diet, and it generally di- 



