260 POULTRY CULTURE 



controlled by a glycogenic nerve center located in the medulla 

 oblongata; therefore, the liver regulates the amount of sugar 

 which should pass into the blood. The amount found in the 

 blood at any one time varies normally from 0.05 to 0.17 per 

 cent. An excess, should the liver fail to regulate the amount 

 of sugar entering the blood, is eliminated by the kidneys and 

 diabetes results. When the amount of sugar in the blood 

 rises above 0.2 per cent, this condition always occurs. 



The glycogen storing power of the hver is limited, and should 

 there be an excessive amount this excess may be stored up in 

 other organs. 



Glycogen is found in large quantities in the musculature of 

 the embryo, which points to the fact that it is used in making 

 rapid growth and development. 



Another function of this important gland is the formation of 

 urea. In cell metabolism, in the disintegration of protein 

 bodies, certain amino-acids, as tyrosin and leucin, are formed. 

 Metabolism consists of two processes — ^namely, katabolism 

 or the tearing-down process and anabolism or the building-up 

 process. It is in the katabolic end that these end-bodies are 

 formed which, by undergoing oxidation in the liver, are con- 

 verted into urea, which is carried by the blood from the liver 

 to the kidneys, where it is eliminated. 



A retention of urea in the body proves very poisonous and 

 excessive quantities cause uremic poisoning, later uremic 

 coma and death. 



The liver also possesses the power of converting certain 

 poisonous compounds into non-poisonous compounds by 

 changing their chemical composition; therefore, one function 

 of the liver is a neutralizer of poisons. 



There are stellate cells in the liver known as the Kupfer 

 cells, which have phagocytic properties — that is, the power to 

 take up bacteria coming in the blood from the intestines and 

 destroying them, thus protecting the body against bacterial 

 invasion. The functions of the liver may be summarized as 

 follows : 



(1) To store up the excessive glycogen. 



(2) To regulate the amount of sugar circulating in the blood, 



(3) To form bile. 



