UREA. 197 



unable to extract it from any other of the solid tissues, under 

 normal conditions, except the substance of the liver. The 

 fact that it exists in considerable quantity in the liver has 

 led to the supposition that this is the organ chiefly concerned 

 in its production. 1 "With the small amount of positive 

 information that we have upon this point, the view that 

 the liver produces urea, while the kidneys are the organs 

 chiefly concerned in its elimination, must be regarded as 

 purely hypothetical. But if it be true that urea is the re- 

 sult of the physiological wear of the nitrogenized elements 

 of the body, the liver would probably produce its share, in 

 the ordinary process of disassimilation. The fact that urea 

 has not yet been detected in normal muscular tissue is by no 

 means a conclusive argument against its formation in this 

 situation. We have lately shown that, although the liver is 

 constantly producing sugar, none can be detected in its 

 substance, for the reason that it is washed out as fast as it 

 is formed, by the current of blood. 2 In the case of the 

 muscles, it is by no means improbable that the lymph, and 

 perhaps the blood, washes out the urea constantly, and keeps 



in rabbits and dogs, after extirpation of the kidneys (Bericht uber Versuche 

 der Uramie betreffend. Zeitschrift fur rationelk Medicin, Leipzig u. Heidelberg, 

 1866, Dritte Reihe, Bd. xxvi., S. 232). 



1 MEISSXER, Beitrdge zur Kenntniss des Stoffwecfisels im thierischen Organis- 

 mus. CentralUatt fur die medidnischen Wissenschaften, 1868, Xo. 18, S. 275. 

 Meissner refers to Heynsius and Stokvis as having previously indicated, though 

 in an imperfect manner, the presence of urea in the liver. Parkes states that 

 when portions of the substance of the liver have been destroyed by disease, the 

 urea is sometimes deficient in the urine, and that it has appeared to him that 

 " the want of urea was hi proportion to the amount of hepatic tissue destroyed " 

 (The Composition of the Urine, London, 1860, p. 284). 



2 FLINT, Jr., Experiments undertaken for the purpose of reconciling some of the 

 Discordant Observations upon the Glycogenic Function of the Liver. New York 

 Medical Journal, Jan., 1869, vol. viii., p. 373, et seq. The experiments detailed 

 hi this article we have since repeated in public demonstrations, and confirmed 

 most fully. In our later observations, we showed absence of sugar in the blood 

 from the portal vein and the substance of the liver, and the presence of a large 

 quantity of sugar in the blood from the hepatic veins. The dog upon which 

 these observations were made was in full digestion. 



