THE STORY OP DIGESTION 49 



the liver this sugar appears to be converted into a 

 starchy substance known as glycogen, or animal 

 starch. Stored up in the cells of the liver, it would 

 seem that this starch is ultimately reconverted into 

 sugar, and paid out to the blood by the hepatic 

 vein which represents the great outlet of the liver 

 into the circulation. Here we might compare the 

 liver to a banker who receives the cheques and 

 drafts of his customers, and pays out money that is 

 required in the form of ordinary currency which can 

 be used to pay the customers' workmen. Some 

 doubt has been cast upon the liver's work as 

 affecting a source of sugar-supply for the body at 

 large, and the muscles especially. It has been 

 contended that the sugar which is stored by the 

 liver is converted into fat, and that any escape of 

 sugar from the liver is to be viewed as an unnatural 

 process. This view, however, has received but slight 

 support from physiologists at large. It seems to be 

 refuted by the fact that the hepatic vein, carrying 

 blood away from the liver, contains a larger pro- 

 portion of sugar than any other vein in the body. 

 If the sugar-supplying duty of the liver be upheld, 

 it is not necessary to reject the idea that the liver 

 may also form fat from the starch it stores up, 

 for we know that starchy foods tend to produce fat 

 and are therefore forbidden to corpulent persons. 

 The probability is that the liver discharges both 

 duties. It gives off sugar, and it may form fat ; the 

 former action being vastly more important than the 

 latter. A proof of the liver's manner of dealing with 

 sugar is afforded by the disease known as diabetes. 

 In this disease there is an excess of output of sugar 

 from the liver, as well as a certain want of action on 

 the part of the sweetbread, the functions of which 



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