PHYSIOLOGY OF THE LIVER AND SPLEEN. 817 



num is followed by an ejection of bile.* It would seem, therefore, 

 that each gush of chyme into the duodenum excites, probably by 

 reflex action, a contraction of the gall-bladder, and an inhibition 

 of the sphincter closing the opening into the intestine. 



An interesting application of this fact has been made in surgical practice. 

 Af ber operations upon the gall-bladder trouble is experienced at times owing 

 to the failure of the fistulous opening to heal, so that there is constant oozing 

 of gall. It is found that frequent feeding of the patient facilitates the per- 

 manent closure of the fistula, because apparently the sphincter is kept inhibited 

 and the pressure in the gall-bladder is lowered. 



The substances in the chyme that are responsible for the stim- 

 ulation have been investigated by Bruns. He finds that acids, 

 alkalies, and starches are ineffective, and concludes that the reflex 

 is due to the proteins and fats or some of the products of their 

 digestion. The gall-bladder has a muscular coat of plain muscle, 

 and records made of its contractions show that the force exerted 

 is quite small. According to Freese,t the maximal contraction 

 does not exceed that necessary to overcome the hydrostatic pressure 

 of a column of water 220 mms. in height, — a force, therefore, which 

 is about equivalent to the secretion pressure of bile as determined 

 by Heidenhain. The innervation of the gall-bladder and gall-ducts 

 has l^een studied especially by Doyon. { It would seem, from the 

 experiments made by this author together with later experiments 

 reported by others, § that the bladder receives both motor and in- 

 hibitory fibers by way of the splanchnic nerves. These fibers emerge 

 from the spinal cord in the roots of the sixth thoracic to the first 

 lumbar spinal nerve, and pass to the celiac plexus by way of the 

 splanchnic nerves. Motor fibers may occur also in the vagi. Sensory 

 fibers capable of causing a reflex constriction or dilatation of the 

 bladder are found in both the vagus and splanchnic nerves. Stim- 

 ulation of the central end of the cut splanchnic causes a dilatation 

 of the bladder (reflex stimulation of the inhibitory fibers), while 

 stimulation of the central end of the vagus causes a contraction 

 of the bladder and a dilatation (inhibition) of the sphincter muscle 

 at the opening of the common duct into the intestine. These 

 latter movements are the ones that occur during normal digestion, 

 and we may assume, therefore, that in the normal reflex emptying 

 of the gall-bladder the afTerent path for the reflex is formed by 

 the vagus fibers while the efferent path is through the splanchnic 

 nerves. 



Effect of Complete Occlusion of the Bile-duct. — When the 

 flow of bile is prevented by ligation of the bile-duct, or when this 



*See also Klodnizki, quoted from Maly's "Jahres-bericht der Thier- 

 chemie," 33, 617, 1904. 



t" Johns Hopkins Hospital Bulletin," June, 1905. 



j Doyon, "Archives de physiologie," 1894, p. 19. 



§ Bainbridge and Dale, "Journal of Physiology," 1905, vol. xxxiii., 138. 



