154 F. A. BAINmiDGE AND H. H. DALE. 



as to the method whereby the entry of gastric contents into the duodenum 

 causes contraction of the gall-bladder if it do so indeed. To settle this 

 question would probably necessitate experiments on an animal with a 

 permanent fistula of the gall-bladder. 



SUMMARY AND CONCLUSIONS. 



1. The gall-bladder shows rhythmic variation in volume : the rhythm 

 is increased in extent after the removal of tonic inhibitory impulses 

 either by section of the splanchnic nerves, or the intravenous injection 

 of chrysotoxin. Spontaneous contractions of the gall-bladder had been 

 previously observed by Doyon. 



2. The normal effect of stimulation of the sympathetic nerve-supply 

 to the muscular coat of the gall-bladder, whether by electrical excitation 

 of the right splanchnic nerve or by intravenous injection of adrenalin, is 

 relaxation. 



The apparently motor effects first described by Doyon are in ail 

 probability due to extraneous causes, namely, the mechanical pressure 

 on the gall-bladder caused by swelling of the liver, and the increased 

 tone of the muscle due to hypersemia. 



We find, however, that the right splanchnic contains an admixture 

 of motor fibres, the presence of which can be detected when the tone 

 of the gall-bladder is lowered by enfeeblement or stoppage of the 

 circulation. 



3. We have confirmed the observations of Courtade and Guy on 

 that the vagus contains motor fibres for the gall-bladder. Definite motor 

 effects are obtained most readily by stimulating the vagus in the thorax 

 after the administration of chrysotoxin. Both the tone and the rhythm 

 of the muscular coat are augmented, though not necessarily to the same 

 degree. The left vagus is the more effective of the two. The effect is 

 abolished by atropine. Stimulation of the central end of the vagi has 

 no influence on the gall-bladder. 



4. We found it impossible under the conditions of our experiments 

 to elicit a reflex contraction of the gall-bladder either by applying acid 

 or the products of gastric digestion to the duodenal mucous membrane 

 or the biliary papilla, or by electrical excitation of the papilla, or by 

 rapid distension of the gall-bladder. We draw no conclusion, however j 

 with regard to the existence of such reflexes in the unanaesthetised 

 animal. 



