264 LECTURE XII. 



pound of glycocoll, while from birds we get one of ornithine. Some of the 

 amino acids, such as cystine, have been directly isolated from normal 

 organs. 



The question whether amino acids are normal constituents of urine, has 

 recently been raised repeatedly. Various answers have been given. If we 

 examine critically the investigations so far published, we shall have to 

 admit that there is no positive proof yet brought forth indicating the 

 presence of amino acids in urine under normal conditions. Glycocoll is 

 the only one that has been identified positively, and this was only accom- 

 plished after the urine had been liberally treated with alkali for many 

 hours; in fact, several days. We can easily imagine that the glycocoll 

 may have been split off from some compound. Until it is possible to 

 show that the amount of this product depends upon the extent of albumin 

 decomposition in the organism, we cannot regard this discovery as proof 

 of the appearance of glycocoll in cell-metabolism. It is noteworthy that 

 only glycocoll has so far been isolated. This amino acid is utilized to a 

 considerable extent for conjugation with aromatic substances, especially 

 benzoic acid. We can easily imagine that the glycocoll found in urine 

 originated from this source. It is very probable that the organism main- 

 tains a supply of glycocoll for just this coupling process. When we con- 

 sider in addition that the kidneys are active producers of hippuric acid, 

 we can appreciate the possibility of glycocoll being flushed into the urine 

 under certain conditions. From the investigations at hand, we are not 

 at all justified in stating that amino acids are normal constituents of 

 urine. 1 



Amino acids are, however, often present in urine in large amounts under 

 certain pathological conditions. This, for instance, occurs in the case of 

 acute atrophy of the liver, a disease in which the albumin decomposition 

 is very rapid. The liver, in this case, is flabby and emaciated. The con- 

 tents of the capsule of Glisson are quite soft, and, in part, semi-fluid. An 

 extensive destruction process has taken place in all the liver cells. Amino 

 acids can be found in the liver-paste, leucine and tyrosine being easily 

 isolated on account of their insolubility. The remaining elements of the 

 albumin molecule, especially those easily split off, are also probably present. 

 The two amino acids mentioned, often crystallize out directly on the liver 

 itself, in the form of a white coating. Leucine and tyrosine have been 

 found in the urine at such times. A very analogous condition arises in 

 phosphorus poisoning. Here, again, we find amino acids in the urine; 

 tyrosine, leucine, and glycocoll 2 having been isolated. Undoubtedly 



1 E. Abderhalden and A. Schittenhelm : Z. physiol. Chem. 47, 1906. G. Embden and 

 H. Reese: Hofmeister's Beitr. 7, 411 (1905). 



2 E. Abderhalden and P. Bergell: Z. physiol. Chem. 39, 464 (1903). E. Abderhalden 

 and L. F. Barker: ibid. 42, 524 (1904). 



