SECRETION OF PANCREATIC JUICE AND BILE. 229 



The following observations on the secretions from the two ducts 

 are now made. 



1. Having observed the normal rate of secretion, a small piece 

 of cotton soaked in a weak solution of hydrochloric acid (less than 

 1%) is placed in the duodenum. Whenever the secretion from the 

 pancreatic duct becomes decidedly increased (not an invariable 

 result) the cotton is removed, and the duodenum washed with 

 physiological saline rendered faintly alkaline by sodium carbonate. 

 Sometimes an increased secretion of bile occurs. From what 

 sources may this bile be derived? What experimental steps would 

 you suggest in order to ascertain this? 



2. The exciting influence of the acid might of course be due 

 to its absorption into the blood. To test this possibility inject 

 some of the acid into the femoral vein. A negative result is ob- 

 tained even when massive doses are injected. 



3. Pieces (about 2 feet long) of the upper end of the jejunum and 

 of the lower end of the ileum are then removed, by cutting between 

 previously applied ligatures, and the contents washed out by tap 

 water. Each piece is then slit open and the mucosa scraped off by 

 the blunt edge of a scalpel and collected in separate watch glasses. 

 One half of each scraping is thoroughly ground in a small mortar 

 with fine quartz sand and about 30 c.c. of 0.6 per cent, hydro- 

 chloric acid (2 c.c. HC1 (Con) in 100 c.c. water.) The extracts are 

 filtered through fine muslin and nearly neutralised (but left dis- 

 tinctly acid towards litmus). About 5 c.c. of the extract of jejunum 

 is then injected into the femoral vein and observations made on 

 the arterial blood pressure, the secretion of pancreatic juice and the 

 secretion of bile. (Prior to this, however, the cystic duct should 

 have been tied off. Why?) The blood pressure usually falls 

 considerably and care must be taken so to regulate the rate (and 

 amount) of injection that the fall is not allowed to go too far. 

 What conclusions regarding the mechanism of the increased secre- 

 tion can be drawn from the results? To obtain satisfactory results 

 it may be necessary to repeat the injection using double the amount 

 and injecting more quickly. 



The observation should then be repeated using a similarly 

 prepared extract of ileum. A much feebler response, if any re- 



