CHEMISTRY OF THE LIVER. 305 



is usually comparatively soft, but that formed in some degen- 

 erations is harder. 



The proportion of lecithins in the liver is variable and is 

 ordinarily below the true fats. The average amount is from 

 2 to 3 per cent. It has a more important function to perform 

 than have the fats proper, since it is found by experiment that 

 in starvation the lecithin fat is the last to disappear. The 

 ether extract of the organ in this case is largely lecithin. 



The most important substance found in the liver is probably 

 glycogen, which is a transformation product and variable in 

 quantity. The amount present at any one moment depends 

 on the carbohydrate consumption and the time which has 

 elapsed since a meal. It may be as high as 15 per cent of 

 the whole weight of the organ or may run down to a fraction 

 of i per cent, after fasting or after the performance of hard 

 work. The formation of glycogen will be discussed below. 



The liver consisting largely of cells in rapid state of change 

 furnishes a relatively large amount of the so-called nitrog- 

 enous extractives. These include the xanthine and related 

 bodies, urea, uric acid, leucine, cystin and other substances 

 representing certain stages in metabolism. The total amount 

 of these compounds present at any one time is very small, and 

 probably not over 0.5 per cent of the dried organ; but even 

 this small amount is important, as will appear below. 



We have finally several mineral substances present. These 

 include essentially the chlorides and phosphates of the alkali 

 and alkali earth metals with some iron compounds. Of the 

 latter those with proteins have been mentioned above, but other 

 iron salts are present and the quantity may be increased by 

 the administration of inorganic substances as remedies. In 

 normal conditions the iron content is extremely variable. 

 The amount may be accurately determined only after washing 

 out the blood (containing hemoglobin) by aid of salt solution 

 of proper strength, about 0.9 per cent. Recent investigations 

 have shown that in the livers of women the iron varies from 

 0.05 per cent to 0.09 per cent of the dry substance, while in 



21 



