LESSON XLV 

 DIGESTION (Continued) 



SECRETION OF PANCREATIC JUICE, ACTION OF SECRETIN. GASTRO- 



ENTEROSTOMY 



1. Preparation of Secretin. Anesthetize a mammal and maintain 

 the anesthesia throughout the following experiments: Perform trache- 

 otomy. Open the abdomen by an incision through the linea alba. 

 Identify the pyloric sphincter. Beginning at this point isolate a 

 segment of intestine about 1 m. in length. Remove it; slit its wall, 

 and wash it thoroughly in running water. Kill the animal by an 

 overdose of ether. Scrape off the mucous lining of the segment of in- 

 testine just removed with a piece of glass, and immerse this material 

 in saline solution and sand. Add to it three or four times its volume of 

 0.4 per cent. HC1 and place it in the ice-chest. Shortly before being 



FIG. 121. DIAGRAM TO SHOW THE POSITION OF THE DUCTS OF THE PANCREAS. 

 D, Duodenum; P, pancreas; DC, ductus choledochus; DW, ductus Wirsungianus; DS, 



ductus Santorini. 



used add KOH to this decoction of the duodenal mucosa until changed 

 to an alkaline reaction. Strain through muslin and filter. As much 

 as 50 c.c. of this preparation should be used at a time. Since the acidi- 

 fied decoction may be kept for some time, it is advisable for economic 

 reasons to prepare it from some of the animals used during one of the 

 exercises immediately preceding. If an animal has been used especially 

 for obtaining secretin, it should be kept until the end of this exercise 

 for purposes of dissection. 



2. Collection of Pancreatic Juice. Anesthetize a mammal and main- 

 tain the anesthesia throughout the following experiments: Perform 

 tracheotomy. Open the abdominal cavity by an incision in the linea 



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