368 HUMAN PHYSIOLOGY 



grms. at a time. But the carbohydrate capacity varies 

 greatly, and even in the same individual it is different under 

 different conditions. When the glycogen stored in the liver 

 is changed to glucose more quickly than is required by the 

 tissues, the glucose accumulates in the blood and is excreted 

 in the urine -(glycosuria). This is seen in Bernard's experi- 

 ment of puncturing the floor of the fourth ventricle at its 

 posterior part in a rabbit. If glycogen is abundant in the 

 liver, glycosuria results. 



Another way in which sugar may be made to appear in 

 the urine is by injecting phloridzin. But since under the 

 influence of this drug the sugar in the blood is decreased, it 

 must be concluded that it acts by causing the kidneys to 

 excrete glucose too rapidly, so that it is not available for the 

 tissues. 



The injection of large doses of extract of the suprarenal 

 bodies causes a glycosuria with an increase of sugar in the 

 blood ; but so far it is not known whether the condition is 

 one of increased production of sugar or of diminished 

 utilisation (p. 385). 



Removal of the pancreas also causes glycosuria (p. 390). 



2. Relation to Fats. Although the fats are not carried 

 directly to the liver, as are proteids and carbohydrates, they 

 are stored in large amounts in the liver of some animals 

 e.g. the cod among fishes and the cat among mammals. 

 Animals which have little power of storing fat generally 

 throughout the muscles and other tissues, seem to have a 

 marked capacity for accumulating it in the liver. Even in 

 starvation the fats do not disappear from the liver, and 

 throughout all conditions of life a fairly constant amount of 

 lecithin a phosphorus and nitrogen containing fat (see 

 p. 78) is present in the liver cells. Lecithin is an inter- 

 mediate stage in the formation of the more complex nucleins 

 of living cells, and the formation of lecithin in the liver by 

 the synthesis of glycerin, fatty acids, phosphoric acid, and 

 cholin is probably a first step in the construction of these 

 nucleins. If this is so, the fat of the liver must play an 

 important part in retaining and fixing phosphorus in the 

 body. 



3. Relation to Proteids. Along with the intestinal wall, 



