CHEMICAL CONSTITUENTS OF THE LIVER-CELLS. 311 



The celiac plexus sends trophic and vasomotor nerves to the liver. Destruc- 

 tion of this plexus therefore causes degeneration of the liver-cells, and dilatation 

 of the hepatic artery. The pneumogastric nerve supplies dilator-fibers to the 

 vessels, and the greater splanchnic motor branches to the muscles of the bile- 

 ducts. 



CHEMICAL CONSTITUENTS OF THE LIVER-CELLS. 



Proteids. The fresh, soft liver-parenchyma has an alkaline re- 

 action. After death, coagulation takes place, with cloudiness of the 

 cell-contents ; the tissue becomes friable and gradually acquires an acid 

 reaction. This process is suggestive of rigor mortis, and is due to 

 a myosin-like, post-mortem coagulating albuminous substance. The 

 liver contains, further, a proteid body coagulable at 45 C., another 

 coagulable at 70 C., and one slightly soluble in dilute acids and alkalies. 

 The nuclei contain nuclein. The connective tissue yields gelatin. 



Glycogen, 6C 6 H 10 5 + H 2 O, or animal starch, from 1.2 to 2.6 per 

 cent., is a carbohydrate closely allied to inulin, soluble in water, and 

 diffusible with difficulty, which surrounds the nuclei of the liver-cells in 

 amorphous granules (Fig. 117, 2), though not always present and not 

 always found in equal amounts in all parts of the liver. The glycogen 

 in the liver represents the excess of carbohydrate material, which, after 

 the ingestion of suitable foods, is temporarily stored like the starch in 

 the plants. It is subsequently transformed into sugar and consumed by 

 the tissues. t 



Qualitative Determination. Glycogen is stained deeply red by iodin (best dis- 

 solved by means of potassium iodid in a concentrated solution of sodium chlorid) , 

 like inulin, even in microscopic sections hardened in alcohol. Organs containing 



?lycogen, boiled with an excess of sodium sulphate, yield an opalescent filtrate, 

 f the organs, as, for example, the liver, still contain diastatic ferment, the glycogen, 

 after being kept warm for several hours, will be converted into sugar, and, as 

 already stated, the resulting filtrate remains clear. 



Quantitative Estimation. According to Kulz's modification of Brucke's 

 method, the coarsely minced liver is thrown into boiling water immediately after 

 death and boiled for half an hour. It is then crushed and potassium hydrate 

 (4 grams to 100 grams of liver) is added. Evaporation over a water-bath to 

 double the weight of the piece of liver employed is permitted to take place until 

 in the course of three hours all is dissolved. After cooling, the mixture is neutral- 

 ized with hydrochloric acid, and the albumin, together with the lime, is precipitated 

 by means of hydrochloric acid, and potassio-mercuric iodid. Filtration is now 

 practised, the precipitate being taken from the filter four times, mixed with 

 a few drops of hydrochloric acid and potassio-mercuric iodid in water to the 

 consistency of broth and filtered. All of the glycogen is now contained in the 

 filtrate, to which, with stirring, double the volume of 96 per cent, alcohol is added. 

 The glycogen deposited in the course of twelve hours is placed upon the filter, 

 washed with 62 per cent, alcohol, then with absolute alcohol, with ether, again 

 with absolute alcohol and dried at 110 C. Should the fluid remain cloudy after 

 addition of hydrochloric acid and potassio-mercuric iodid, two parts of 98 per cent, 

 alcohol are added and the filtered precipitate is dissolved in 2 percent, potassium 

 hydrate, then neutralized with hydrochloric acid and now all of the albumin 

 can be precipitated by repeated addition of hydrochloric acid and potassio-mer- 

 curic iodid again. 



According to Seegen, dextrin is present in the liver in addition to glycogen. 

 Rabbit's liver contains about three times as much glycogen in winter as in summer. 



The following are to be considered as the sources of glycogen in the 

 liver: (i) The carbohydrates of the food, after they have been con- 

 verted into dextrose in the alimentary canal; only the sugars ferment- 

 able by yeast form glycogen, and not those incapable of fermentation; 



