GALL BLADDER. 139 



The following method which we ultimately adopted, and found in 

 most ways quite satisfactory, is that devised by Doyon 1 , with modifica- 

 tion in details. A thin balloon of india-rubber is tied over the end of a 

 gum elastic catheter, about 1 inch of the catheter being inside the 

 balloon. The catheter is connected by a length of small-bore india-rubber 

 tubing with a wide glass reservoir half filled with water, and usually at 

 a height of about 15 cm. above that of the gall-bladder. The upper end 

 of this reservoir is connected by rubber-tubing with a small Hiirthle 

 piston-recorder. The balloon is inserted in the deflated condition 

 through a small cut made in the fundus of the gall-bladder, tied in, and 

 then filled with warm water from the reservoir. 



In our earlier experiments the abdominal wound was closed. Under 

 such conditions several evident sources of error presented themselves. 

 Variations of external pressure to which the gall-bladder yields passively 

 are registered by the recorder and may be quite indistinguishable from 

 the effects of active contraction of the muscular wall of the bladder 

 itself. Such variations may be caused by : 



(1) Varying contraction of the abdominal walls and diaphragm. 



(2) Activity of contiguous contractile viscera. 



(3) Changes in volume and turgescence of the liver substance, with 

 which the gall-bladder is frequently in contact over the greater part of 

 its surface. 



These difficulties were met as follows : 



(1) The animal was either fully curarised, or the chest was opened, 

 the phrenic nerves cut and the diaphragm divided according to a method 

 to be described later. The abdominal walls were widely opened by a 

 crucial incision and the flaps held back by weighted hooks, the gall- 

 bladder being protected from cold and evaporation by frequently renewed 

 flannels soaked in warm saline, or by immersing the animal in a warm 

 saline bath. If insufficient attention be given to this protection against 

 cooling it is very easy, when the sympathetic nerve-supply is stimulated, 

 and especially when adrenalin is the mode of stimulation, to produce an 

 effect of simple hypersemia of the gall-bladder muscle, which will be 

 described later. 



(2) Care was taken to prevent contact with contractile viscera by 

 drawing these aside with hooks and screening the gall-bladder with 

 sponges and flannels. These measures, however, were merely precau- 

 tionary, since the danger of disturbance from this cause is but slight 



1 Doyon, Archives de Physiol. xxv. p. 678. 1893. 



102 



