ABSORPTION AND THE ROUTES OF FOOD. 359 



Fourth. The emulsified fats changed physically and 

 chemically are carried by the lacteal and thoracic duct and 

 dropped into the general circulation. 



We have now to consider the physiological consequence 

 of the transfer of these sugars and proteids to the liver be- 

 fore reaching the circulation at large. 



THE GENERAL PHYSIOLOGY OF THE LIVEE. 



Some of the most important functions of the liver are in 

 connection with the phenomena of general assimilation, and 

 a discussion of the liver from this standpoint is reserved for 

 the next chapter. We have to do in this connection only 

 with the function of the liver as it affects the proteids and 

 the carbohydrates in their passage through it into the body. 



1. Glycogenic Function. The most apparent function 

 of the liver, and one of the most important as well, is its 

 formation of glycogen. Glycogen resembles very much 

 ordinary starch in many particulars, and is, in fact, fre- 

 quently called animal starch. The liver forms this gly- 

 cogen by changing the dextrose carried to it by the portal 

 vein, into this compound. The point to the formation of 

 this glycogen is the ability of the liver to store this sub- 

 stance in its cells and then to dole it out to the blood from 

 time to time as it is needed. It would, of course, be prac- 

 tically impossible to store in an organ flushed with circula- 

 ting blood dialyzable dextrose, but by changing the dextrose 

 into an insoluble starch like glycogen it is easily retained. 



The question might naturally arise concerning the ne- 

 cessity of storing any of the dextrose at all, and the objec- 

 tions to having all of it pass into the general circulation at 

 once. These questions are readily answered. In the first 

 place, quite a large amount of each meal is carbohydrate 

 food, and if all this in the form of dextrose should be in- 

 jected into the blood at once it would materially alter the 

 composition of the blood and so lead to nutritive disturb- 

 ances. The prime necessity of the blood is a practically 

 uniform composition. In the second place, such largely 



