GALL BLADDER. 149 



doubt that there is some admixture of motor fibres in the sympathetic 

 nerve-supply to the gall-bladder. This, however, requires special 

 conditions for its detection, and when the tone is maintained by an un- 

 impaired circulation we find that inhibition is the invariable effect of 

 exciting the sympathetic nerve-supply, and are disposed to attribute 

 most of the motor effects described by previous observers to extraneous 

 pressure. We find, further, that the sympathetic fibres to the gall- 

 bladder run in the right splanchnic nerve only. 



III. EFFECT OF THE VAGL 



Doyon 1 regarded the vagus as carrying only afferent impulses from 

 the gall-bladder. On stimulating the central end of either vagus he 

 observed inhibition of the gall-bladder tone. Presumably both the 

 splanchnics were left intact. He obtained a similar result by stimu- 

 lating the central end of either splanchnic when the other was intact. 



Courtade and Guyon 2 , accepting Doyon's account of the motor 

 function of the splanchnics, examined the vagi for efferent fibres to the 

 gall-bladder. Stimulating these nerves in the thorax they observed a 

 motor response from the gall-bladder. They state that these motor 

 fibres run in the gastric branches of the vagus, and claim to have traced 

 them along the lesser curvature of the stomach to the cystic duct. 



Our own experiments have been few in number, and have been 

 confined to the confirmation of the motor effect of the vagus, without 

 tracing the course of the fibres beyond the thorax. The effect is, in our 

 experience, quite a small one and by no means easy to demonstrate. 

 Stimulating the vagi peripherally in the neck, after a dose of atropine 

 sufficient to abolish cardiac inhibition, we only onc~e succeeded in pro- 

 ducing an effect on the gall-bladder, and that merely a slight, though 

 distinct and regularly produced augmentation of existent rhythmic 

 contractions. Stimulation of the vagi intra-thoracically, even after 

 section of the splanchnic nerves on both sides, gave no clear and unmis- 

 takable result unless chrysotoxin had been previously administered. It 

 has been shown, in other connexions, that this drug, while not affecting 

 sympathetic inhibitory nerve-endings to such an extent as to abolish 

 the effect of adrenalin or of electrical stimulation, so far alters them as 

 to block the normal tonic inhibitory impulses from the central nervous 

 system or the ganglionic plexus, allowing stimulation of the cranial 



1 Doyon. loc. cit. 



- Courtade and Guyon. C. R. Soc. de Biol. LVI. pp. 313 and 874. 1904. 



