EXCRETORY FUNCTION OF THE LIVER. 451 



late in tlie blood when their formation in the liver is disturbed. The research^- <f 

 Bidder and Schmidt and others have shown that, although we cannot detect the biliary 

 salts in the blood or chyle coming from the intestine, these principles are not discharged 

 in the faeces. All of these facts point to an important function of the bile as a secretion. 

 It is true that it is discharged constantly, but, during digestion, its flow is very much 

 more abundant than at any other time. It is pretty well established that, during the 

 intervals of the flow of the secretions, the glands are manufacturing the materials of 

 secretion, which are washed out, as it were, in the great afflux of blood which takes 

 place during what has been called the functional activity of the gland. Now, if the liver, 

 in addition to its function as a secreting organ, be constantly forming bile for the purpose 

 of eliminating an excrementitious matter, it is to be expected that the bile would al- 

 ways contain a certain proportion of its elements of secretion. 



The constant and invariable presence of cholesterine in the bile assimilates it in every 

 regard to the excretions, of which the urine may be taken as the type. Cholesterine 

 always exists in the blood and in certain of the tissues of the body. It is not produced 

 in the substance of the liver, but is merely separated from the blood by this organ. It 

 is constantly passed into the intestine, and is discharged, although in a modified form, in 

 the faeces. We know of no function which it has to perform in the economy, any more 

 than urea or any other of the excrementitious principles of the urine ; and we have 

 shown, in the memoir already referred to, that it accumulates in the blood in certain 

 cases of organic disease of the liver and gives rise to symptoms of blood-poisoning. 



Origin of Cholesterine. Cholesterine exists in largest quantity in the substance of 

 the brain and nerves. It is also found in the substance of the liver probably in the 

 bile contained in this organ the crystalline lens, and the spleen ; but, with these excep- 

 tions, it is found only in the nervous system and blood. Two views present themselves 

 with regard to its origin. It is either deposited in the nervous matter from the blood, or 

 it is formed in the brain and taken up by the blood. This is a question, however, which 

 can be settled experimentally, by analyzing the blood for cholesterine as it goes to the 

 brain by the carotid and as it comes from the brain by the internal jugular. The cho- 

 lesterine being found also in the nerves, and, of course, a large quantity of nervous mat- 

 ter existing in the extremities, it is desirable at the same time to make an analysis of the 

 venous blood from the general system. 



With a view of determining this question, we made the following experiments : 



Experiment I. In this experiment, specimens of blood were taken from the carotid, 

 the internal jugular, the vena cava, hepatic veins, hepatic artery, and portal vein, in a liv- 

 ing animal (a dog about six months old). In addition, we took a specimen of bile from 

 the gall-bladder, and some of the substance of the brain. These were all carefully ex- 

 amined for cholesterine, and the following were the main results : In the brain, choles- 

 terine was found in large quantity. There was no cholesterine in the extract of the 

 blood from the carotid, examined three days after, and but a few crystals, eleven days 

 after. Cholestewne was almost immediately discovered in the extract of the blood from 

 the internal jugular, and the crystals were present in large numbers on the twelfth day. 

 In this experiment, the animal was etherized when the blood was taken, and the examina- 

 tions for cholesterine were not quantitative. In the succeeding experiments, the propor- 

 tion of cholesterine in the different specimens of blood was accurately estimated, and, in 

 most of them, no anaesthetic was used during the operative procedure. 



Experiment II. A medium-sized adult dog was put under the influence of etlur. ;u <1 

 the carotid artery, internal jugular, and femoral vein exposed. Specimens of blood wi-iv 

 drawn, first from the internal jugular, next from the carotid, and last from the femoral 

 vein. These specimens were received into carefully-weighed vessels, and weighed. They 

 were then analyzed for cholesterine by the process already described, with the follow- 

 ing results : 



