304 PHYSIOLOGICAL CHEMISTRY. 



new tissues. The chemistry of lecithin, as a complex fat, has 

 been explained already. Glycogen and cholesterol are also 

 constant constituents of cells, but of their uses there nothing 

 definite is known. 



FUNCTIONS OF THE LIVER CELLS. 



The anatomical location of the liver gives it a most im- 

 portant relation to the other organs of the body. With the 

 exception of the fats most of the products of the digestion of 

 foods pass through the portal vein into the liver and there 

 undergo certain preparatory changes. Substances not true 

 foods take the same course and many toxic bodies, metallic 

 and alkaloidal, find a resting place in the liver. In toxico- 

 logical examinations the liver, after the stomach, is the most 

 important organ for analysis. 



Not only are the fundamental food stuffs, the proteins and 

 the carbohydrates, worked over and more or less altered in 

 the liver, but partly metabolized products seem to be further 

 changed in passing through this organ and are there brought 

 into a condition for final excretion. The evidences that such 

 reactions take place have been worked out in a number of cases 

 experimentally and will be referred to below. 



Composition of the Liver. We have here the materials 

 found in cells in general and also others having special func- 

 tions. The protein substances separated belong to several 

 groups; albumin, globulin and a nucleo-proteid have been rec- 

 ognized. Iron exists in combination with several of these 

 protein bodies. One of these is known as ferratin and con- 

 tains the iron in complex combination; others appear to be 

 albuminates in which the iron is more readily recognized. 



Next to the proteins the fats are relatively abundant in the 

 liver and may amount to 3 or 4 per cent by weight normally. 

 Pathologically, by fatty degeneration, or by filtration from 

 other tissues, the fat may be greatly increased, even to 30 or 

 35 per cent of the weight of the whole organ. The liver fat 



