536 DIGESTION. 



fats occurs in the intestinal canal, and also as the fatty acids do not 

 occur in the chyle as such, but as emulsified fat after a synthesis with 

 glycerin into neutral fats, it is to be doubted whether the emulsified 

 fat of the chyle originates from an absorption of emulsified fat in the 

 intestine or from a subsequent emulsification of neutral fats formed 

 synthetically. This doubt has greater warrant in the observation of 

 FRANK l that the fatty-acid ethyl ester is extensively taken up from the 

 intestine, not as such, but as split-off fatty acids from which then the 

 neutral emulsified fats of the chyle are formed. 



The assumption of an absorption of fats as an emulsion is inconsist- 

 ent with the fact that an emulsion produced by means of soaps is not 

 permanent in an acid liquid; hence we cannot consider as possible the 

 presence of an emulsion in the intestine so long as it is acid. This 

 difficulty is not too serious, as the reaction is often only due to carbonic 

 acid and bicarbonates, and besides as found by RUHNE and recently 

 shown by MOORE and KRUMBHOLZ, 2 the proteins have a preserving 

 action upon fat emulsions. 



The earlier opinions as to fat absorption were, that fat was absorbed 

 as soaps, soluble in water, as well as finely emulsified fat, and this last 

 form was considered as of the greatest importance. This view has 

 recently undergone essential modifications, due to the work of MOORE 

 and ROCKWOOD, and especially to the extensive work of PFLUGER. 3 



MOORE and ROCKWOOD have shown the great solvent action of the 

 bile for fatty acids, and on continuing these investigations further, 

 MOORE and PARKER have found that the bile increases the solubility 

 of soaps in water, and can prevent their gelatinization, a fact which is 

 of greater importance for the absorption of fats than the solubility of 

 the fatty acids in bile. The quantity of lecithin in the bile is of great 

 importance for the solubility therein of the fatty acids as well as the 

 soaps. According to the above-mentioned investigators, the absorption 

 of fat from the intestine is essentially dependent upon the solubility of 

 the soaps and free fatty acids in the bile. The neutral fats are split 

 and the free fatty acids are in part absorbed, dissolved as such by the 

 bile, and in part combined with alkalies, forming soaps. Neutral fats 

 are regenerated from the fatty acids, and the alkali set free from the 

 soaps is secreted again into the intestine and used for the re-formation 



1 Zeitschr. f. Biologie, 36. 



2 Kiihne, Lehr. der physiol. Chem., 122; Moore and Krumbholz, Journ. of Physiol., 

 22. 



3 In regard to the recent literature on fat absorption, see the works of Pfliiger, 

 Pfluger's Arch., 80, 81, 82, 85, 88, 89, and 90, where the work of other investigators is 

 cited and discussed. See also Croner, Bioch. Zeitschr. 23; Lombroso, Arch, di Fisiol. 5. 



