362 PHYSIOLOGICAL CHEMISTRY. 



but its chemical constitution is that of an alcohol. It is found 

 chiefly in bile, but also in blood, nerve-tissue, brain, contents of 

 the intestines, feces, etc ; its presence in certain vegetables, as 

 peas, beans, etc., has also been demonstrated. 



Cholesterin crystallizes in colorless, silky needles, which are 

 insoluble in water, alkalies, and diluted acids, but soluble in 

 ether. It sometimes forms in the organism solid masses, 

 known as biliary calculi or gallstones, some of which are almost 

 pure cholesterin. 



Tests for choksterin: 



1. Evaporated with nitric acid it gives a yellow mass, which 

 turns brick-red on addition of ammonia. 



2. Mixed in the dry state with strong sulphuric acid, it pro- 

 duces a blue-red or violet color on the addition of chloroform, 

 the color changing to green on exposure to air. 



3. Evaporated with a mixture of 2 volumes of sulphuric acid 

 and 1 volume of ferric chloride solution, it turns violet. 



Lecithins. Lecithin, one of the constituents of bile, is the 

 member of a group of substances generally termed phosphorized 

 fats or lecithins. These bodies are highly complex in composi- 

 tion, and may be looked upon as fats formed from glycerine, in 

 which hydrogen atoms are replaced by the radicals of phos- 

 phoric and fatty acids. 



Pancreatic juice. There is no thoroughly reliable analysis of 

 this highly complex liquid on record. It contains from 3 to 6 

 per cent, of solids, two-thirds of which are of organic, one-third 

 of inorganic nature. Among the organic constituents are a 

 number (certainly two, probably more) of cryptolites or animal 

 ferments, which manifest themselves: 1, by converting starch 

 into sugar (this action is more energetic than that of ptyalin); 



2, by converting albuminoids into peptones (this action takes 

 place in alkaline, but not in acid solution, as in case of pepsin); 



3, by emulsifying neutral fats; 4, by decomposing fats into gly- 

 cerine and fatty acids. 



Feces consist of that portion of the food which has not been 

 taken into the system by absorption, and is discharged from the 

 body mixed with some of the products of the biliary and intes- 



