262 ABSORPTION LYMPH AND CHYLE 



important uses in the active processes of nutrition. The quantity and 

 the proportion of solid constituents are rather increased than diminished 

 in animals deprived of food and drink for several days ; while starvation 

 always impoverishes the blood from the first. ' On the other hand, urea, 

 one of the most important of the products of katabolism, undoubtedly 

 is taken up by the lymph and conveyed to the blood. 



Properties and Composition of Chyle. During the intervals of diges- 

 tion, the intestinal lymphatics and the thoracic duct carry lymph ; but 

 so soon as absorption of the products of digestion begins, certain nutri- 

 tive matters are taken up in quantity by these vessels, and their contents 

 are known under the name of chyle. 



In the human subject and in carnivorous animals, the chyle, taken 

 from the lacteals near the intestine, where it is nearly pure, or from the 

 thoracic duct, when it is mixed with lymph, is a white, opaque, milky 

 liquid, of a slightly saline taste and an odor said to resemble that of the 

 semen. The odor is also said to be characteristic of the animal from 

 which chyle is taken ; although this is not very marked, except on the 

 addition of a concentrated acid. The reaction of the chyle is either 

 alkaline or neutral. Its specific gravity is less than that of the blood ; 

 but it is variable and depends on the quality of food and particularly 

 the quantity of liquids ingested. 



The differences in the appearance of the chyle in different animals 

 depend chiefly on the food. The chyle is milky in the carnivora, espe- 

 cially after fats have been taken in quantity ; but in dogs nourished with 

 articles containing but little fat, its appearance is hardly lactescent. The 

 chyle is almost transparent in herbivora fed with hay or straw. 



It is impossible to give an accurate estimate of the entire quantity 

 of chyle taken up by the lacteal vessels. When it finds its way into the 

 thoracic duct, it is immediately mixed with all the lymph from the lower 

 extremities ; and the large quantities that have been collected from 

 this vessel give no idea of the quantity of chyle absorbed from the intes- 

 tinal canal. No attempt will be made, therefore, to give even an approxi- 

 mate estimate of the absolute quantity of chyle ; but it is evident that 

 this is variable, depending on the nature of the food and the quantity of 

 liquids ingested. 



Like the lymph, the chyle, when removed from the vessels, under- 

 goes coagulation. Different specimens vary considerably as regards 

 rapidity of coagulation. Chyle from the thoracic duct usually coagu- 

 lates in a few minutes. The first portion of the liquid collected from 

 the human subject by Rees the chyle was collected in this case in two 

 portions coagulated in an hour. Received into an ordinary glass ves- 

 sel, the chyle separates more or less completely, after coagulation, into 



