Besides these branches of the portal and hepatic veins and hepatic artery another set of vessels ramifies in the liver, namely the bile ducts, whose business it is to carry off the bile produced by the activity of the cells. A very remarkable and interesting experiment, per formed by a Polish anatomist named Chrzon szczewsky, shows where the bile-ducts origi nate. This investigator injected into the veins of some animals a particular (lye, indigo-car mine. An hour and a half afterwards the animal was killed, and examination of speci mens of the liver under the microscope dis played the colouring matter collected round the cells of the liver in channels which were thus for the first time revealed. if the animal were killed sooner, the colouring matter was found in the cells themselves. It thus became apparent that the liver cells seized upon the colouring matter in the blood brought to them, separated it out, and passed it into channels surrounding them. The channels are shown in Fig. 108 (a). They are the beginnings of the bile-ducts. It may be supposed that, in a similar fashion, the cells of the liver take from the blood flowing past them certain materials from which they prepare the bile, which is then discharged into the surrounding ducts. From them the bile passes from between the cells out of the lobule into larger ducts, which collect the bile from numerous lobules. These ducts unite with others from other parts of the liver until, in the end, two channels are formed, one of which carries all the bile formed by the right portion of the liver, and the other that from the left portion. These two ducts come out from the substance of the liver and soon unite into one main vessel—the hepatic duct, which passes towards the small intestine. On the under surface of the liver
is the gall-bladder, in which the bile may be stored till needed for digestion. From the gall-bladder a duct passes—the cystic duct. It joins the duct from the liver, and the com mon bile-duct, formed by the junction of the two, reaches the first part of the small intes tine, through whose walls it passes to open on the inner surface a few inches below the sto mach. The bile, then, prepared in the depths of the liver by the liver cells, is conveyed out of the liver by the bile-ducts, and may pass straight down and into the small intestine to mingle with the food. If, however, digestion be not going on, the mouth of the bile-duct is closed, and in that case the bile passes up the cystic duct and lodges in the gall-bladder till required.
Fig. 109 shows the connections of the various parts spoken of, and the figure should be studied in the light of the above explana tions.
Plate XIV. represents the relationship be tween the liver and its duct and gall-bladder, and between these and the stomach and small bowel. In particular, it may be here pointed out how near to the small end of the stomach is the place where the bile-duct pours the bile into the small bowel. It will easily be under stood how, by the act of retching, the pressure exerted on the gall-bladder, &c., may force bile up from the bowel into the stomach, the re verse of its usual direction. From the stomach it would then be ejected by vomiting. Under such circumstances a person is apt to attribute his retching to bile, whereas it was the retch ing that forced the bile up into the stomach, and the cause of the sickness may therefore have been elsewhere.