306 SECRETION. 



The proposition that the blood from the hepatic veins does 

 not contain sugar during life and health cannot be sustained 

 by actual experiment. Observers may say that the quantity 

 is very slight, but its existence in this situation, indepen- 

 dently of the kind of food taken, cannot be denied. Dr. 

 Pavy, who is the originator of the theory that the sugar 

 found in the liver and in the blood coming from the liver 

 is due to a post-mortem change, nowhere states that he has 

 taken the blood from the hepatic veins and failed to find 

 sugar. He states that he has found the blood taken from 

 the right side of the heart by catheterization, in a living 

 animal, " scarcely at all impregnated with saccharine mat- 

 ter," l but he does not deny its presence in small quantity. 

 In twelve examinations made by Dr. M'Donnell, of Dublin, 

 traces of sugar were found in five specimens of blood taken 

 from the right auricle by catheterization, in the living ani- 

 mal, and no sugar was detected in seven. 8 It must be re- 

 membered, in considering these experiments, that the blood 

 of the right side of the heart is the mixed blood from the 

 entire body ; and, assuming that the hepatic blood is con- 

 stantly saccharine, the quantity in the blood of the right 

 heart would not be very great. 



In opposition to these experiments, which are only par- 

 tially negative, we have the following results of examina- 

 tions of the blood of the hepatic veins and of the right side 

 of the heart taken as nearly as possible under normal condi- 

 tions. 



To demonstrate the absence of sugar in the portal vein 

 and its constant presence in the hepatic veins in dogs fed ex- 

 clusively on meat, Bernard employed the following process : 

 The animal was killed instantly by section of the medulla 

 cblongata. A small opening was then made into the abdo- 

 men, just large enough to admit the finger and to enable 



1 PAVY, Researches on the Nature and Treatment of Diabetes, London, 1862, 

 PP- 44, 46. 



2 M'DONNELL, Observations on the Functions of the Liver, Dublin, 1865, p. 4. 



