CHYLE. 529 



been deprived of food and drink for several days ; while it 

 is well known that starvation always impoverishes the blood. 1 

 On the other hand, urea, one of the most important of the pro- 

 ducts of destructive metamorphosis of the tissues, is undoubt- 

 edly taken up by the lymph, and conveyed in this fluid to 

 the blood. It remains now for future investigations to deter- 

 mine whether other excrementitious principles may not be 

 taken up from the tissues in the same way a question of 

 great importance in its relations to the mechanism, of excre- 

 tion. 



What is positively known with regard to the functions 

 of the lymph may be summed up in a very few words : A 

 great part of its constituents is evidently derived from the 

 blood; and the relations of these principles (fibrin, albumen, 

 and the ordinary inorganic salts) to nutrition are not under- 

 stood. The same may be said of sugar, also a constant con- 

 stituent of the lymph, the origin of which, even, is not known. 

 Urea and, perhaps, other excrementitious matters are taken 

 up from the tissues by the lymph, and are discharged into 

 the blood, to be removed by the appropriate organs from the 

 system. 



While the blood is evidently the great nutritive fluid of 

 the body, being constantly regenerated and purified by the 

 absorption of nutritive matters, by respiration, and by the 

 action of excreting organs, the lymph has an important 

 function in removing from the tissues some, at least, of the 

 products of physiological decay of the organism. 



Chyle. 



During the intervals of digestion, the intestinal lymphat- 

 ics and the thoracic duct carry ordinary lymph ; but as soon 

 as absorption of alimentary matters begins, certain nutritive 

 principles are taken up in quantity by these vessels, and 

 their contents are now known as the chyle. But little re- 

 mains to be said concerning this fluid, as we have consid- 



1 Loc. cit. 

 34 



