ABSORPTION AND THE ROUTES OF FOOD. 361 



the placenta, but especially in the voluntary muscles. 

 These voluntary muscles seem to be able to take some of 

 the sugar out of the blood and store it up as glycogen 

 within themselves as a reserve supply to fall back upon in 

 times of activity. A muscle which has been working for 

 some time loses all its glycogen. This reserve supply has 

 been used by the muscle to build up its tissues. It is an 

 attempt of these organs to have at their immediate disposal 

 a certain reserve supply without being directly dependent 

 upon the blood-stream at critial moments. The difference 

 between the voluntary muscles and the liver, however, is 

 that the reserve supply of glycogen in the muscles is in- 

 tended merely for the use of the muscles, while the liver 

 acts as a temporary storehouse for the entire system. 



We have now followed the sugar into the liver, watched 

 its change into the animal starch called glycogen, saw it 

 stored in the liver cells and between meals doled out again 

 to the blood as sugar. What further change this sugar suf- 

 fers in the circulation and in the tissues to which it has been 

 carried will be discussed in the chapter on nutrition. 



2. The Albumens. The albumens, too, are carried to 

 the liver. One might be tempted at first to suppose that 

 the sudden excess of albumens also is stored here, and then 

 like the sugar is dropped back into the blood as necessity 

 requires. But there is no place in the body where albu- 

 mens can be stored. All the albumens available are in the 

 circulating blood and lymph. Fats may be stored in fatty 

 tissue and remain stored there for a long time. Sugars 

 may be temporarily stored in the liver, but there is no 

 storehouse for the albumens. These must drop into the 

 general circulation at once. Here, however, the danger 

 would present itself of increasing excessively the amount of 

 albumens in the blood after a meal, and so producing 

 nutritive disturbances here as well as with the sugars. 

 Even a greater danger might ensue. The accumulating 

 albumens of the blood might begin to be eliminated from 



