512 DIGESTION. 



Emulsification used to be considered as of the greatest importance in 

 the absorption of fats, and this emulsion occurs in the chyle on the intro- 

 duction into the intestine of not only neutral fats, but also of fatty acids. 

 The fatty acids do not exist as such in the emulsified fat of the chyle. 

 The investigations of I. MUNK, later confirmed by others, have shown 

 that the fatty acids undergo in great part a synthesis into neutral fats 

 in the walls of the intestine, and are carried as such by the stream of 

 chyle into the blood. This synthesis seems to take place in the mucous 

 membrane (MOORE and others l ) . 



The assumption that the fat is absorbed chiefly as an emulsion is 

 partly based on the abundance of emulsified fat in the chyle after feeding 

 with fat, and partly on the fact that a fat emulsion is often found in the 

 intestine after such food. As an abundant cleavage of neutral 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 2 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 KUHNE and recently 

 shown by MOORE and KRUMBHOLZ, 3 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. 4 



1 Munk, Virchow's Arch., 80. See also v. Walther, Arch. f. (Anat. u.) Physiol., 

 1890; Minkowski, Arch. f. exp. Path. u. Pharm., 21; Frank, Zeitschr. f. Biologie, 30; 

 Moore, see Biochem. Centralbl., 1, 741; Frank and Ritter, Zeitschr. f. Biologie, 47. 



2 Zeitschr. f . Biologie, 36. 



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

 22. 



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

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

 is cited and discussed. 



