334 FOOD AND DIGESTION 



watery, or from a newly opened duct. The solids vary in a temporary fistula 

 from 80 to 100 parts per thousand, and in a permanent one from 16 to 50 per 

 thousand. It is characterized by having three distinct and important en- 

 zymes known as trypsin, amylopsin, and steapsin, whose actions are respect- 

 ively, proteolytic, amylolytic, and lipolytic (fat-splitting). Maltase, which 

 inverts the disaccharides, is also present, and some have stated that rennin is 

 found in pancreatic juice. 



CHEMICAL COMPOSITION or PANCREATIC JUICE. (C. SCHMIDT.) 



Recent Permanent 



From a dog. fistula. fistula. 



Water 900.76 980.45 



Solids 99-24 19 . 55 



Organic substances QO-44 12.71 



Ash 8.80 6.84 



Sodium carbonate 0.58 3.31 



Sodium chloride 7.35 2.50 



Calcium, magnesium, and sodium phosphates -53 0.08 



An extract of pancreas made from the gland which has been re- 

 moved from an animal killed during digestion possesses the active properties 

 of pancreatic secretion. It is made by first dehydrating in absolute alcohol 

 the gland which has been cut up into small pieces. After the entire removal 

 of the alcohol the gland is pulverized and extracted in strong glycerin. 

 The amount of the ferment greatly increases if the gland be exposed to the 

 air for three or four hours before placing in alcohol; indeed, a glycerin 

 extract made from the gland immediately upon the removal from the body 

 often appears to contain none of the ferments. The conversion of zymogen 

 in the gland into the ferment takes place only after the gland stands a while. 

 Dilute acid assists or accelerates the conversion, and if a recent pancreas be 

 rubbed up with dilute acid before dehydration, a glycerin extract made 

 afterward, even though the gland may have been only recently removed from 

 the body, is very active. 



Nervous Regulation of the Secretion of the Pancreas. Fibers from 

 the vagus and from the splanchnics are distributed to the pancreas. In 

 Pawlow's laboratory it has been found that stimulation of these nerves leads 

 to the increased secretion of the pancreas. Popielski, in studying the effects 

 of dilute hydrochloric acid solution in the duodenum, which resulted in a 

 marked increase of pancreatic secretion, explained the phenomenon as a 

 local nerve reflex. 



Doubt has been cast on the whole question of nervous control by the recent 

 discovery of the fact that acid (0.4 per cent hydrochloric acid) in the duodenum 

 results in the production of a chemical substance, secretin, by the duodenal 

 mucous membrane. This secretin is absorbed into the circulation and acts 

 specifically on the pancreas to produce increased activity by the pancreatic 

 cells. Acid extracts of the duodenal mucous membrane produce the same 



