PANCREATIC JUICE AND ITS ACTION UPON FOOD. 175 



great importance in the digestive process, although the precise limits 

 of its operation are not yet fully determined. 



In the first place, the pancreatic juice has the power of transforming 

 starch into sugar. This action takes place with great rapidity at the 

 temperature of the living body. According to Hardy, 1 it is much more 

 prompt as well as more complete than the corresponding change 

 produced by saliva, being at the temperature of 40 (104 F.) almost 

 instantaneous; and, while the transforming action of saliva is very 

 partial, much of the starch remaining unchanged, that of the pancreatic 

 juice appears to convert the whole of it into glucose. Kroeger found 2 

 that one gramme of fresh pancreatic juice, at the temperature of 35 

 (95 F.), transformed into sugar, within thirty minutes, 4.67 grammes 

 of starch ; while, according to our own observations, if one gramme of 

 fresh human saliva be mixed at 38 (lOQOF.), with a watery solution 

 containing less than 0.1 gramme of boiled starch, though the sugar re- 

 action becomes manifest in one minute, a large portion of the starch 

 is still unchanged at the end of an hour. It is certain that hydrated 

 starch, although it may be recognized for a long time in the stomach 

 by its iodine reaction, disappears completely as soon as it enters the 

 upper part of the duodenum. According to Ranke, 3 pancreatic juice 

 causes the transformation not only of hydrated, but also of raw starch; 

 a property which was found by Bouchardat and Sandras to be very 

 energetic in the secretion of the common fowl, if aided by a slight ele- 

 vation of temperature. 



The organic matter of the pancreatic juice, which produces this 

 change, is coagulable by a boiling temperature, and after its solution 

 has once been boiled, it is inactive in regard to starchy matters. It is 

 produced in the substance of the gland, probably by the transformation 

 of some previousl} 7 " formed material, since it has been found by Liver- 

 sidge, 4 that after it lias been completely extracted from the chopped 

 glandular tissue by treatment with glycerine, if the inactive residue be 

 transferred to a filter, and allowed to remain exposed to the air for five 

 or six hours, it is regenerated, and may be again extracted by the addi- 

 tion of water or glycerine. This is undoubtedly due to a real reproduc- 

 tion of the active organic substance, and is not the result of a putrefac- 

 tive change, since the same observer found that a watery extract of the 

 pancreas, which had once been deprived of its action on starch by boil- 

 ing, never regained this property at any stage of subsequent decompo- 

 sition. 



Secondly, the pancreatic juice has the power of emulsifying the fats. 

 This is perhaps its most marked and peculiar property, by which it is 



1 Chimie Biologique. Paris, 1871, p. 152. 



2 Cited in Milne Edwards, LeQons sur la Physiologic. Paris, 1862, tome vii. 

 p. 68. 



3 Physiologic des Menschens. Leipzig, 1872, p. 271. 



4 Studies from the Physiological Laboratory of the University of Cambridge, 

 Part I. Cambridge, 1873, p. 49. 



