560 SPECIAL PHYSIOLOGY. 



istic milk-white fluid, containing fatty particles. To this apparently 

 precise and unexceptionable experiment, it has been objected, by those 

 who dispute the influence of the pancreatic juice in the digestion of 

 fatty matters, that the difference in the contents of the lacteals, above 

 and below the entrance of the pancreatic duct, depends upon the time 

 that has elapsed before the animal is killed after being fed with fat. 

 When this is done within two hours, it is said that the lacteals given 

 off above the pancreatic duct are found filled with white chyle ; but 

 if the animal be killed from four to six hours after, the lacteals below 

 the pancreatic duct are alone filled. These results are not in accord- 

 ance with the experience of most observers, who fully confirm those 

 obtained by Bernard. It is further stated by that experimenter, that 

 ligature of the pancreatic duct arrests the emulsification and absorp- 

 tion of fat ; but this, again, is disputed by others. The opposite con- 

 ditions observed by them, are explained by Bernard, on the supposi- 

 tion, either that the smaller pancreatic duct escaped ligature, or that 

 certain minute glands of the duodenum in part supplied the place of 

 the pancreas. It has been asserted, that if the small intestine be 

 tied, in cats and puppies, below the entrance of the pancreatic duct, 

 and oil, mixed with milk, be injected into the bowel below the ligature, 

 the lacteals, after a time, become filled with white chyle (Frerichs). It 

 is also said, that after the formation of a pancreatic fistula in a cow, 

 chyle collected from a fistula, subsequently made in the thoracic duct, 

 contains almost as much fat as that of other cows in which no pancre- 

 atic fistula has been established (Colin and Lasaigne). Furthermore 

 it is objected, that no large amount of saponified fat is found either 

 in the contents of the intestine, or in the chyle itself, as might be ex- 

 pected, if the pancreatic juice decomposed the neutral fats, and so 

 rendered them absorbable (Bidder and Schmidt). 



To conclude : first, the pancreatic juice exercises a positive power 

 of converting starch into sugar, and so may aid in digestion. Secondly, 

 its digestive power over albuminoid and gelatinoid bodies, when it is 

 fresh, is very slight, but more marked when it is acidified, or when it 

 co-operates with the gastric juice. Thirdly, it possesses a remarkable 

 power of emulsifying fat, and rendering it absorbable, more marked 

 even than that of the bile. Lastly, whilst, out of the body, it not only 

 emulsifies, but also decomposes the neutral fats into their fatty acids 

 and glycerin. It is uncertain whether this decomposition actually takes 

 place within the body. 



A case has been recorded, in which a calf's pancreas, taken inter- 

 nally, aided the assimilation of fat ; and, quite recently, preparations 

 of pancreatin .made from animals, like those of pepsin long employed, 

 have been administered medicinally. 



Action of the Intestinal Juices. 



Owing to the mixture of secretions in- the intestinal canal, it is dif- 

 ficult to determine the digestive properties of the intestinal juices. 

 Portions of food, inclosed in perforated tubes, have been introduced 

 through artificial openings, into the small intestine, the duodenum 



