230 EXPERIMENTAL PHYSIOLOGY. 



sponse at all, is observed, but the fall in blood pressure is as pro- 

 nounced as before. What conclusions do you draw from the result? 



4. Having demonstrated the secretagoguary action of the duo- 

 denal extract, the question arises as to the general nature of the excit- 

 ing substance. The remaining portion of the acid extract of jejunum 

 is therefore boiled (in faintly acid reaction) and filtered through thin 

 filter paper. The filtrate is found to be still active when injected. 

 What conclusions do you draw? Has any change occurred in the 

 vaso-depressor effect? The secretion of bile is often observed to 

 respond to the injections in the same manner as the pancreatic 

 juice, and its behaviour therefore should be carefully watched. 



5. Having established, by these experiments, that acid extracts 

 a pancreatic hormone from the mucosa (seeretin) the question arises 

 as to whether the hormone is present therein as such or as a pre- 

 cursor which the acid activates. To throw light on this question, 

 the unextracted half of the mucosa scrapings is ground in a mortar 

 with quartz sand, and 0.9 per cent, sodium chloride solution, and 

 after filtering the extract through muslin, about half of it is in- 

 jected intravenously. The result is negative. The remaining 

 portion of the extract is then rendered faintly acid with HC1, 

 boiled and filtered. (3n injection a slight, but yet definite increase 

 usually occurs in pancreatic secretion. What conclusions are per- 

 missible from these results? 



6. Finally the influence of the intravenous injection of a solution 

 of bile salts on the outflow from the bile duct should be observed. 



