448 CHEMISTR Y OF THE DIGESTIVE PROCESSES. 



the production of fatty acid by pancreatic juice, although he was the 

 discoverer of this saponifying action. He states that, when neutral oil 

 is shaken up with pancreatic juice, an instantaneous emulsion takes 

 place; and, secondly, when neutral oil is submitted to the prolonged 

 action of pancreatic juice, fatty acids are developed. Bernard con- 

 sidered the formation of emulsion in the intestine as a more important 

 process than saponification, due to a ferment action, and speaks of a 

 "ferment emulsif" It is now certainly known that fatty acids are 

 always formed in the intestine after the ingestion of fat, but an emulsive 

 ferment is no longer believed in. The rapidity of fresh pancreatic juice 

 in forming fatty acid is remarkable; thus Eachford, 1 in very favour- 

 able cases, found that a sufficient amount of fatty acid to form a spon- 

 taneous emulsion (5 '5 per cent.) is formed in presence of bile and' 

 hydrochloric acid at room temperature in two minutes. This very 

 rapid action explains the error into which Bernard fell. 2 



Pancreatic juice obtained from a permanent fistula has less emulsive 

 power than that from a temporary fistula ; it is also poorer in proteid, and, 

 according to Kiihne, 3 the emulsive power does not depend upon the alkali, 

 for faintly acid juice is capable of producing emulsion. Minkowski is of the 

 opinion that it is chiefly to the proteid that emulsion is due, basing his 

 opinion on the observation, made by Abelmann 4 in his laboratory, that after 

 excision of the pancreas no fat except that of milk is absorbed ; unless minced 

 pancreatic tissue be taken with the food, when other fats are also absorbed. 

 These observations have been confirmed by Sandmeyer. 5 



Some observers 6 hold that emulsification does not occur at all inside the 

 intestine, and others 7 state that a considerable amount of emulsification takes 

 place, but that the granules of fat in the emulsion are not nearly so small as 

 those found in the chyle. 



Cash 8 found, in four experiments on dogs, that there was no emulsion 

 in the intestine during active fat absorption. Moore and Kockwood, 9 in six 

 out of sixteen experiments, obtained a similar result, but in the other ten 

 experiments found emulsions in the intestine, containing fat globules of 

 various dimensions, some of considerable size, but many exceedingly minute. 

 These results indicate that in the dog at least, fats can be broken up and 

 absorbed without undergoing previous emulsification. Still it should be 

 borne in mind that these two different conditions of the intestine in the 

 dog during fat absorption may be phases of the same process. The contents 

 of the stomach are not discharged continuously into the duodenum, but from 

 time to time the pyloric sphincter is relaxed, and a portion of the contents 

 of the stomach ejected. It may well be that the condition of no emulsion is 



1 Journ. PhysioL, Cambridge and Loiidon, 1891, vol. xii. p. 92. 



2 The statement that the fat-splitting action of the pancreatic enzyme is very slow, and 

 hence that probably only a small percentage of fat is so decomposed in the intestine 

 (see Bunge, "Lehrbuch," Atifl. 3, S. 175), undoubtedly arises from most observers using 

 not pancreatic juice but pancreatic extracts, in which the easily decomposable fat-splitting 

 enzyme was only present in traces. Rachford's results with pancreatic juice clearly indicate 

 that the pancreatic secretion is capable within the time of digestion of a fatty meal of 

 decomposing all the fat into fatty acids and glycerin. 



3 "Lehrbuch d. physiol. Chem.," 1868, S. 122. 



4 Inaug. Diss., Dorpat, 1890. 



5 Ztschr.f. BioL, Miinclien, 1895, Bd. xxxi. S. 40. 



6 Cash, Arch.f. Anat. u. Physiol, Leipzig, 1880, S. 323; Altmann and Krehl, ibid., 

 1889, Anat, Abth., Stipp. Bd. S. 86 ; 1890, Anat. Abth., S. 97. 



7 Heidenhain, Arch. f. d. ges. PhysioL, Bonn, 1888, Supp. Heft, Bd. xliii. S. 88, 

 Other recent observers who describe an emulsion in the intestine are, Lebedeff, Arch. f. 

 Anat. u. PhysioL, Leipzig, 1883, S. 504 ; Lewin, Arch. f. d. ges. PhysioL, Bonn, 1896, Bd. 

 Ixiii. S. ISO. 



8 Loc. cit. 9 Journ. PhysioL, Cambridge and London, 1897, vol. xxi. p. 74. 



