ABSORPTION 279 



acts as a solvent for lecithin and cholesterin, and so aids in 

 the excretion of these otherwise insoluble bodies. Secondly, it 

 acts as a solvent in the intestine for both free fatty acids and 

 soaps, conferring their entire solubility on the former, and largely 

 increasing the solubility of the latter (Moore). The solvent 

 properties of the bile are chiefly due to the bile salts, but in the 

 case of the fatty acids and soaps the amount dissolved is greatly 

 increased by the simultaneous presence of lecithin. As the 

 supreme function of the bile salts is to render the fatty acids and 

 soaps soluble and fit for absorption, the utility of the reabsorption 

 of these salts in other words, the circulation of the bile salts 

 is obvious. Lecithin and cholesterin become precipitated when 

 the bile salts are reabsorbed. Cholesterin possesses a very low 

 solubility even in bile, hence gall-stones are frequently formed of 

 this substance. These important discoveries show why it is the 

 fat-absorbing power of the intestine is most seriously impaired 

 either by absence of the bile or pancreatic juice. In the absence 

 of the juice the unemulsified fats are not broken up, till they 

 reach the action of bacteria in the large intestine, and then it is 

 too late, for the solvent bile salts have been mostly absorbed. On 

 the other hand, in the absence of the bile the fats are split by 

 the juice, but the fatty acids and soaps are not brought into 

 solution. 



ABSORPTION 



From the intestine at the height of digestion of a fatty 

 meal there are absorbed fatty acids and soaps dissolved in the 

 bile and glycerine. On the other hand, in the thoracic duct 

 90-95 per cent, of the fat is in the form of neutral fat. Thus 

 somewhere, either in the cells of the intestinal mucosa or in the 

 lymphoid tissue, lymph, the synthesis of neutral fat, must be 

 brought about. Is it effected by an intracellular enzyme, or is 

 it a process which the living cell protoplasm effects, acting as 

 an energy transformer ? These are the questions which Moore 

 has recently answered. He collected the chyle by pricking the 

 milk-white lacteals of a dog after a meal rich in fats, taking 

 up the drops in capillary tubes. The tubes were weighed, and 

 then placed in a test-tube of ether. After extraction of the fat 



