424 THE METABOLISM OF THE PURIN BODIES 



mammals, there being in birds an easy natural anastamosis 

 between these two through the vein of Jacobson which joins 

 together the portal vein and the vena advehens (running 

 from the tail and pelvis to the kidneys). By ligaturing the 

 portal vein above this anastamotic branch, the portal blood does 

 not traverse the liver, and this latter can now be excised, except 

 the portion of it which immediately surrounds, and is intimately 

 adherent with, the hepatic vein. To excise this latter part would 

 mean too much bleeding, but it can be crushed so as to render it 

 functionless. In Minkowski's experiments the geese lived from six 

 to twenty hours after the liver extirpation, during which time 

 this experimenter found the amount of uric acid in the urine 

 to be markedly diminished and ammonium lactate to be corre- 

 spondingly increased. The replacement of uric acid by ammonium 

 lactate pointed to lactic acid as the substance which furnishes 

 the carbon chain ; the ammonia increase being of course also due 

 to the absence of any synthesis of uric acid. 



Before Minkowski's explanation of this result could be accepted, 

 however, it had to be shown that the lactic acid was not produced 

 in some other way. Lactic acid in the urine may occur in a 

 variety of conditions, such, for example, as in severe liver disease 

 in man, in phosphorus poisoning, and also in conditions associated 

 with deficient tissue oxidation. In fact, Hoppe-Seyler ( 20 ) sug- 

 gested that deficient oxidation, due to the operative interference 

 impeding the movements of respiration, might be the cause of its 

 appearance in Minkowski's birds. That such was not the case has, 

 however, been shown by Minkowski himself; for the same lactic 

 acid excretion occurred after all the blood-vessels going to the liver 

 were tied but no liver extirpation practised. It might, however, be 

 possible, as Bunge( 28 ) suggested, that lactic acid had been pro- 

 duced by the removal of the liver, not because uric acid formation 

 was inhibited, but from some other unknown cause ; that this free 

 acid acted like any other free acid in the tissues would (see art. 

 Diabetes, p. 372), in that it used up all the available alkali, until 

 there was no alkali left but ammonia, with which it then combined, 

 and thereby prevented from being transformed into urea and uric 

 acid (see also Milroy's expt., p. 393). Minkowski, however, showed 

 this explanation to be incorrect and the want of synthesis to be 

 the main cause of lactic acid excretion by feeding liverless geese 

 on urea ; no increase was thereby produced in uric acid excretion, 



