BODY TISSUES AND FLUIDS 463 



Las a relatively high content of creatin, Myers has observed that the potas- 

 sium is present in fairly high concentration, 0.46 per cent calculated as 

 K (average for 8 animals). In conditions such as starvation, which ulti- 

 mately bring about a reduction in the creatin, it is of interest that the 

 potassium, as a rule, shows a proportionate reduction. 



Without further discussion it may be said that there are many observa- 

 tions which lead one to believe that glycogen, creatin, phosphoric acid and 

 potassium are closely associated in active muscle. 



Liver and the Bile 



An appreciation of the importance of the liver to the animal organism 

 may be gained from the following facts. The liver is the largest gland 

 of the body. Its extirpation in mammals quickly results in death. The 

 blood from the digestive tract first passes through the liver before reach- 

 ing the general circulation. The liver appears to be a temporary store- 

 house for all classes of foodstuffs, carbohydrate (glycogen), fat and pro- 

 tein (ammo-acids). Many poisons both inorganic and organic are retained 

 by the liver, many of the latter being detoxicated. Numerous chemical re- 

 actions, in which deamidization, hydrolysis, oxidation and reduction occur, 

 take place in the liver. The liver also appears to be chiefly concerned in 

 the synthesis of urea (uric acid in birds), sugar from protein and the 

 ethereal sulphates. The formation of fibrinogen and also serum albumin 

 and globulin has been ascribed to the liver. 



Less is known concerning the proteins of the liver than of the muscle. 

 There are two proteins, apparently globulins, which coagulate at 45 and 

 75 respectively, and a nucleoprotein which coagulates at 70 C. Besides 

 these proteins which are soluble there are others in the cells which are 

 difficultly soluble. The fat (fatty infiltration) of the liver is derived 

 not only from an excess of fat in the diet, but also by transportation from 

 other parts of the body. The phosphatids (lecithin) are normal constitu- 

 ents of the liver and are subject to much less variation than the fat. 

 Cholesterol is also a normal constituent but found in small amounts. As 

 in the muscle, phosphoric acid and potassium are the mineral constituents 

 which are present in the highest concentrations. Compared to other tis- 

 sues iron appears to be present in fairly large amounts. It. is of interest 

 that considerable iron is stored in the liver during fetal life, apparently 

 to provide for the deficiency in the diet during the period of lactation. 



The storing of carbohydrate in the liver in the form of glycogen 

 is one of the liver's many important functions. The credit for the dis- 

 covery of glycogen and this glycogenic function of the liver, i. e., the 

 ability of the liver to convert glucose to glycogen and glycogen to glu- 

 cose, is due to Bernard. In normal animals the quantity of glycogen in 



