336 ABSORPTION. 



of the clot indicating the proportion of fibrin. The serum which thus separates is quite 

 variable in quantity and is never clear. Its milkiness does not depend entirely upon the 

 presence of particles of emulsified fat, and it is not rendered transparent by ether. It con- 

 tains, in addition to these particles, numerous leucocytes and organic granules. 



Numerous observations have been made with reference to the influence of different 

 kinds of food upon the chyle ; but these have not been followed by any definite results 

 that can be applied to the human subject. It is usual to find the chyle fluid in the lac- 

 teals and in the thoracic duct for many hours after death ; but it soon coagulates after ex- 

 posure to the air. Although the entire lacteal system is sometimes found, in the human 

 subject and in the inferior animals, filled with perfectly opaque, coagulated chyle, the 

 fluid does not often coagulate in the vessels. 



Composition of the Chyle. Analyses of the milky fluid taken from the thoracic duct 

 during full digestion by no means represent the composition of pure chyle ; and it is only 

 by collecting the fluid from the mesenteric lacteals, that it can be obtained without a 

 very large admixture of lymph. In the human subject, it is rare even to have an oppor- 

 tunity of taking the fluid from the thoracic duct in cases of sudden death during diges- 

 tion ; and, in most of the inferior animals which have been operated upon, it is difficult to 

 obtain fluid from the small lacteals in quantity sufficient for accurate analysis. In oper- 

 ating upon the ox, however, Colin has succeeded in collecting pure chyle in considera- 

 ble quantity. 



The most complete analysis of chyle from the human subject is given by Dr. Eees. 

 The fluid was taken from the thoracic duct of a vigorous man, a little more than an hour 

 after his execution by hanging. The subject was apparently in perfect health up to the 

 moment of his death. The evening before, he ate two ounces of bread and four ounces 

 of meat. At seven o'clock A. M., precisely one hour before death, he took two cups of 

 tea and a piece of toast ; and he drank a glass of wine just before mounting the scaffold. 

 When the dissection was made, the body was yet warm, although the weather was quite 

 cold. The thoracic duct was rapidly exposed and divided, and about six fluidrachms of 

 milky chyle were collected. The fluid was neutral and had a specific gravity of 1024. 

 The following was its proximate composition : 



Composition of Human Chyle from the Thoracic Duct. 



Water 904*8 



Albumen, with traces of fibrinous matter 70 - 8 



Aqueous extractive 5'6 



Alcoholic extractive, or osmazome 5'2 



Alkaline chlorides, carbonates, and sulphates, with traces of alkaline phosphates 



and oxides of iron 4'4 



Fatty matters 9-2 



1,000-0 



Of the constituents of the chyle not given in the ordinary analyses, the most impor- 

 tant are the urea, which, in all probability, is derived exclusively from the lymph, and 

 sugar, coming from the saccharine and amylaceous articles of food during the digestion 

 of these principles. 



The difference in chemical composition between the unmixed lymph and the chyle is 

 very well illustrated in a comparative examination of these two fluids taken from a don- 

 key. The fluids were collected by Mr. 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 Dr. Rees : 



