BILE, PANCREATIC JUICE, AND SUCCUS ENTERICUS. 279 



bile taken from the gall-bladder, and therefore containing much more 

 mucus as well as, relatively to the solids, more water than bile from the 

 hepatic duct. 



In 1000 parts. 



Water 859.2 



Solids : 



Bile Salts 91.4 



Fats, etc 9.2 



Cholesterin 2.6 



Mucus and Pigment 29.8 



Inorganic Salts 7.8 



140.8 



The entire absence of proteids is a marked feature of bile : pancreatic 

 juice, as we shall see, contains a considerable quantity ; saliva, as we have 

 seen, a small quantity; normal gastric juice probably still less, and bile none 

 at all. Even the bile which has been retained some time in the gall-bladder, 

 though rich in mucus, contains no proteids. 



The constituents which form, apart from the mucus, the great bulk of 

 the solids of bile, and which deserve chief attention, are the pigments and 

 the bile-salts ; of these we shall speak immediately. 



With regard to the inorganic salts actually present as such sodium salts 

 are conspicuous, sodium chloride, amounting to 0.2 or more per cent., 

 sodium phosphate to nearly as much, the rest being earthy phosphates 

 and other matters in small quantity. The presence of iron, to the 

 extent of about 0.006 per cent., is interesting, since, as we shall see, 

 there are reasons for thinking that the pigment of bile, itself free from 

 iron, is derived from iron-holding haemoglobin ; some, at least, of the 

 iron set free during the conversion of haemoglobin into bile pigment, 

 which probably takes place in the liver, finds its way into the bile. 

 Bile also appears to contain a small quantity, at all events occasionally, 

 of other metals, such as manganese and copper ; metals introduced into 

 the body are apt to be retained in the liver and eventually leave it by 

 the bile. 



The small quantity of fat present consists in part of the complex body, 

 lecithin. 



The peculiar body, cholesterin, which though fatty-looking (hence the 

 name "bile fat") is really an alcohol with the composition G 26 H 44 O, is con- 

 spicuous by its quantity and constancy. It forms the greater part of most 

 gall-stones, though some are composed chiefly of pigment. Insoluble in 

 water and cold alcohol, though soluble in hot alcohol and readily soluble 

 in ether, chloroform, etc., it is dissolved by the bile-salts in aqueous solution 

 and hence is present in solution in bile Its physiological functions are 

 obscure. 



The ash of bile consists largely of soda, derived partly from the sodium 

 chloride and partly from the bile-salts, of sulphates derived chiefly if not 

 wholly from the latter, and of phosphates partly ready formed and in part 

 derived from the lecithin. 



214. Pigments of bile. The natural golden-red color of normal human 

 or carnivorous bile is due to the presence of bilirubin. This, which is also 

 the chief pigmentary constituent of gall-stones, and occurs largely in the 

 urine of jaundice, may be obtained in the form either of an orange-colored 

 amorphous powder or of well-formed rhombic tablets and prisms. Insoluble 

 in water, and but little soluble in ether and alcohol, it is readily^ soluble 

 in chloroform and in alkaline fluids. Its composition is C 16 H 18 N 2 O 3 . Treated 



