FATE OF GLYCOGEN IN THE ORGANISM 337 



of sensory nerves does cause increased production of sugar from 

 the liver is an undoubted fact. 



Fourthly, as a result of a large number of carefully conducted 

 analyses, Pavy concludes that the amount of sugar in venous and 

 arterial blood is practically the same. The average of his 

 analyses for arterial blood is 0'941 grm. and for venous blood 

 0-938 grm. per 1000 grm. blood. _ i 



The third and fourth " proofs," we see, depend on the 

 quantitative analysis of the blood for sugar, a process which is, 

 technically, very difficult and is subject to a considerable experi- 

 mental error. Moreover, even if between meals the liver should 

 add dextrose to the blood of the hepatic vein, the percentage 

 increase of sugar thus created could be only very slight, on 

 account of the enormous amount of blood which passes through 

 the organ. In his criticism of Bernard's second proof, Pavy 

 takes it as certain that the hepatic cells contain no active 

 diastatic ferment during life. That this is incorrect has been 

 definitely shown by Pick. 1 



The balance of evidence stands in favour of Bernard's theory. 



The transformation of the glycogen of the liver into sugar 

 proceeds very rapidly immediately after death, and then slows 

 down, so that, even after several days, there still remains some 

 unchanged glycogen. Thus Pavy states that the living normal 

 liver contains from O'l to 0*4 per cent of sugar: a few minutes 

 after death this rises to from 1/2 to To per cent., and in about 

 twenty-four hours it amounts to from 2 to 3'5 per cent. 



Such a result would at first sight seem to point to some 

 vital process which, gradually dying, causes the falling off in 

 the production of sugar. In speaking of the cause of the trans- 

 formation as a "vital process," we mean a living state of the 

 protoplasm of the cells ; some workers hold to this view. 2 Other 



1 In support of his theory Pavy gives histological evidence of the conversion 

 of glycogen into fat, not only in the liver but also in the intestine. He considers 

 the intestinal epithelium the first barrier against the passage of sugar into the 

 blood ; what escapes this retention filter (sic) being caught up by the liver. 



2 It should, however, be pointed out that Pavy himself does not believe in 

 the "vital process" theory, but thinks this post-mortem sugar production to be 

 entirely due to some ferment contained in the blood which comes to act on the 

 liver glycogen after death. 



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