v INTEENAL EESTITUTIVE SECEETIONS 335 



observed a marked increase of ammonia in the urine, associated 

 with a considerable diminution of uric acid, which (as we shall see 

 elsewhere) takes the place in birds of the urea of mammals. 



These data show that the depurative action of the liver upon 

 the ammoniacal compounds developed in the digestive apparatus of 

 mammals and birds, consists in their synthetic conversion into 

 urea or uric acid, respectively. 



Hahn, Massen, Nencki and Pawlow (1892) deflected the portal 

 circulation from the liver by joining the portal vein, which had 

 previously been tied near the hilum of the liver, with the inferior 

 vena cava. This ingenious experiment was first carried out by 

 Eck in 1877, and afterwards repeated by Stolnikow, when some of 

 the operated dogs survived. Those which survived the experi- 

 ments of the Eussian investigators exhibited phenomena of auto- 

 intoxication towards the tenth day from the operation consisting 

 in sensory and motor disturbances, which developed into clonic 

 and tetanic convulsions, recurring in spasms. The excitatory 

 phenomena were succeeded by a cofnatose period in which some 

 animals died, while others recovered comparative health. Careful 

 observation showed that these attacks of auto-intoxication were 

 exhibited by the dogs that had eaten most meat. Pawlow and 

 Massen induced similar attacks in operated dogs by forced feeding 

 with an excessive quantity of nitrogenous foods. 



When Nencki and Hahn (who took charge of the chemical part 

 of the work) discovered a large amount of carbamic acid in the 

 urine of the operated dogs, it occurred to Pawlow and Massen to see 

 whether the phenomena of intoxication were due to this abnormal 

 product, which would under natural conditions be converted by the 

 liver. On injecting carbamate of sodium or calcium, to an amount 

 of 0'25 grm. per kilo, body-weight into the veins of a normal dog, 

 they noted nervous disturbances similar to those seen in dogs with 

 Eck s fistula, while the same salt introduced into the alimentary 

 canal was innocuous, even in larger doses. They noted, further, 

 that the administration of sodium carbamate by the mouth, even 

 in smaller doses, in dogs with Eck's fistula, produced a similar 

 poisoning to that obtained with a flesh diet. From this they 

 concluded that the toxic agent which produces the spasms of auto- 

 intoxication in the operated dogs is represented by the carbamic 

 acid, which is normally neutralised by the hepatic cells, and gives 

 rise to the formation of urea, carbonic acid and water, according 

 to Drechsel's theory. The Eussian experimenters confirmed this 

 conclusion by excising a large part of the liver in dogs with Eck's 

 fistula, and tying the hepatic artery, when a comatose state was 

 at once produced, followed by strong convulsions which led to 

 death after 6-12 hours. 



The liver in animals with Eck's fistula was found to be 

 atrophied, with partial fatty degeneration. The kidneys showed 



