266 THE FUNCTIONS OF THE LIVER. 



oxidation -processes in birds. Phlorizin causes glycosuria, even after extirpation of the liver, 

 which shows that in these cases there are other causes at work that obtain in the forms of 

 glycosuria.] Phlorizin makes animals, which are free from carbohydrates, diabetic. In this 

 case the sugar must be derived from proteids (v. Mering). 



Theoretical. In order to explain the more immediate cause of these phenomena several 

 hypotheses have been advanced : 



(a) The'liver-glycogen may be transformed unhindered into sugar, as the blood in its passage 

 through the liver deposits or gives up the ferment to the liver-cells. So that the normal 

 function of the vaso-motor system of the liver, and its centre in the floor of the fourth 

 ventricle, may be regarded "as, in a certain sense, an "inhibitory system" for the formation 

 of sugar. 



(b) If we assume that, normally there is continually a small quantity of sugar passing from 

 the liver into the hepatic vein, we might explain the diabetes as due to the disappearance of 

 these decompositions diminished burning-up of the sugar in the blood, which are constantly 

 removing the sugar from the blood. In fact, diabetic persons have been found to consume less 

 and to have an increased formation of urea. 



[Injection of Grape-Sugar into the Blood. When grape-sugar is injected into the jugular 

 vein of a dog, only 33 per cent, at most is given off in the urine ; within 2 to 5 hours the 

 urine is free from sugar. Even within a few minutes after the injection, only a certain propor- 

 tion (-) of the sugar is found in the blood ; part of the sugar has been detected in the muscles, 

 liver, and kidneys, but the fate of the remainder is not known. Immediately after the injec- 

 tion, the amount of haemoglobin and also of serum-albumin is diminished (50 per cent.), which 

 is due to increase of the quantity of water within the vessels ; but within two hours the normal 

 state is restored (Brasol). In a curarised dog the injection of grape-sugar into a vein increases 

 the blood-pressure, but this effect is not observed after the injection of morphia and chloral.] 



Persons suffering from diabetes require a large amount of .food ; they suffer greatly from 

 thirst, and drink much fluid. They exhibit signs of marked emaciation, when the loss of the 

 body is greater than the supply. [In advanced diabetes the glycogenic function of the liver is 

 almost abolished, as was proved by removing with a trocar a small part of the liver from man, 

 when almost no glycogen was found (Ehrlich). The absorbed sugar in the portal vein passes 

 directly into the general circulation without being submitted to the action of the liver (v. 

 Frerichs).] In severe cases, towards death, not unfrequently a peculiar comatose condition 

 diabetic coma occurs, when the breath often has the odour of aceton, which is also found in 

 the urine. But neither aceton nor its precursor, aceto-acetic acid, nor sethyl-diacetic acid, nor 

 the unknown substance, in diabetic urine, which gives the red colour with ferric chloride (v. 

 Jaksch), is the cause of the coma {Frcrichs and Brieger). 



176. THE FUNCTIONS OF THE LIVER. [To understand the functions 

 of the liver, we must remember its unique relation to the vascular and digestive 

 systems, whereby many of the products of gastric and intestinal digestion have to 

 traverse it before they reach the blood, and some of them as they traverse the 

 liver are altered. We have still much to learn regarding the liver. It has several 

 distinct functions some obvious, others not. (1) The liver secretes bile, which is 

 formed by the hepatic cells, and leaves the organ by the bile-ducts, to pass into 

 the duodenum. (2) The liver-cells also form glycogen, which does not pass into 

 the ducts, but in some altered and diffusible form passes into the blood-stream, 

 and leaves the liver by the hepatic veins. Hence, the study of the liver materially 

 influences our conception of a secreting organ. In this case, we have the products 

 of its secretory activity leaving it by two different channels the one by the ducts, 

 and the other by the blood-stream. The liver, therefore, is a great storehouse of 

 carbohydrates, and it serves them out to the economy as they are required. All 

 this points to the liver as being an organ intimately related to the general 

 metabolism of the body. (3) In a certain period of development it is concerned 

 in the formation of blood-corpuscles ( 7). (4) It has some relation to the 

 breaking up of blood-corpuscles and the formation of urea and other metabolic 

 products ( 20, 177, 3). (5) Brunton attributes some importance to the liver in 

 connection with the arrest of certain substances absorbed from the alimentary 

 canal, whereby they are either destroyed, stored up in the liver, or, it may be, 

 prevented from entering the general circulation in too large amount. It is possible 

 that ptomaines may be arrested in this way ( 166).] 

 [The liver has no special action on certain mineral substances which traverse it in the blood, 



