KATABOLISM. 447 



third source, for starving animals still continue to make 

 liver sugar. Glycogen must also be made from waste 

 tissue. Remember, again, that waste also is split some- 

 where into a combustible and an incombustible part, the 

 one eliminated by the lungs as C0 2 and H 2 0, the other 

 by the kidneys as urea. Now, again, is it not probable 

 that the. place of splitting is the liver, and the combusti- 

 ble portion is glycogen ? The splitting has long been 

 known. My view is that the place is the liver, the com- 

 bustible product glycogen, and the incombustible urea. 



Therefore, according to my view, there are three 

 sources of glycogen : (1) The whole of the amyloids de- 

 hydrated and detained in the liver, (2) the combustible 

 part of the albuminoid food excess, and (3) the combus- 

 tible part of the waste tissue. But since in adults waste 

 is equal to repair, this is equivalent to the whole of the 

 amyloids and the whole of the combustible part of the 

 albuminoid food, or the whole combustible food. 



But there are also exactly the same three sources of 

 vital force. Therefore the whole purpose of this function 

 of the liver is the preparation of fuel, and the only fuel used 

 in the animal body is glycogen. The liver prepares the fuel, 

 the lung burns it, the kidney removes the incombustible 

 residue, or ash. The only food not taken into account 

 here is the fats. How this is burned, whether directly, 

 or whether it also, as is most probable,* is changed into 

 glycogen, is not certainly known. f 



Strong confirmation of this view, so far as waste is 

 concerned, is brought out by some experiments of 

 Schiff. J If the trunk vessels of the liver of a dog (Fig. 

 306, page 442) be ligated so that the blood can not trav- 



* Chittenden, Nature, lv, 303, 1897. 



t Berthelot, Rev. Sci., viii, 129, 1897. Chittenden, Sci., v, 

 517, 1897. 



I Arch, des Sci., lviii, 293, March, 1877. 

 30 



