410 USES OF THE LIVER DUCTLESS GLANDS. 



the substance of the liver and in the blood of the hepatic veins as due to post- 

 mortem action, and his observations seemed to be directly opposed to those 

 of Bernard. The views of these two observers and their followers seemed to 

 be harmonized by a series of experiments made in 1868. If the abdomen of 

 a dog, perfectly quiet and not under the influence of an anaesthetic, be opened, 

 and a portion of the liver be excised, rinsed in cold water and rapidly cut up 

 into boiling water, the extract will show no reaction with Fehling's test for 

 sugar. In one experiment, in which twenty-eight seconds elapsed between 

 the time of opening the abdomen and the action of the boiling water, the 

 reaction with Fehling's test was doubtful. In an experiment in which the 

 time was only ten seconds, there was no trace of sugar in the extract from 

 the liver (Flint). Dalton, however, in 1871, found small quantities of sugar 

 in extracts of portions of liver taken from an animal in an average time of 

 6 J seconds ; but it is possible that the sugar may have been in blood retained 

 in the liver. All observers, however, are now agreed that sugar is formed in 

 the liver very rapidly after death. 



If the view be correct, that the glycogen of the liver is being constantly 

 transformed into sugar during life, and that this sugar is carried away 

 in the blood-current, as fast as it is formed, sugar would not necessarily be 

 contained in the liver under normal conditions ; and there is no actual antag- 

 onism between the results obtained by Bernard and the fact that sugar itself 

 is not a normal constituent of the liver, as is asserted by Pavy, McDonnell, 

 Meissner, Eitter and others. 



If the liver be washed by a stream of water passed through its vessels 

 until it is free from sugar, and if it be kept at the temperature of the body 

 for a few hours, sugar will appear in abundance (Bernard, 1855). This is 

 due to a conversion of the glycogen of the liver into sugar by a ferment, which 

 has been extracted and isolated by Bernard and others by a process analogous 

 to that by which similar ferments have been extracted from the saliva and 

 the pancreatic juice. This ferment probably exists originally in the liver 

 and does not appear first in the blood. 



The question of the transformation of glycogen into sugar during life 

 depends upon the comparative quantities of sugar in the blood going to and 

 coming from the liver. Bernard always found sugar in quantity in the blood 

 of the hepatic veins taken immediately after death, and it exists in blood 

 drawn during life by a catheter introduced into the right cavities of the 

 heart ; while in the carnivora, under a purely animal diet, no sugar is con- 

 tained in the blood of the portal system. The normal blood contains, per- 

 haps, a small quantity of sugar 0-5 to 1 part per 1,000 but the proportion 

 is always greater in the blood of the hepatic veins. 



The characters of animal sugar do not materially differ from those of glu- 

 cose, except that it ferments more readily and is destroyed in the system 

 with great facility. This property of the sugar which results from the gly- 

 cogen formed in the liver is probably of great importance. The sugar which 

 results from digestion is all carried to the liver. Here it is changed into 

 glycogen ; and it is probable that without this change into glycogen and its 



