ALBUMINS OR PROTEINS. 247 



ligated the vessels of the kidneys of dogs, and then introduced benzoic 

 acid and glycocoll into the remaining circulation. The animals experi- 

 mented upon were killed after 3 or 4 hours, and the blood and liver 

 tested for hippuric acid. Benzoic acid, but never hippuric acid, was 

 found. The exact proof that the kidneys of the dog is as a matter of 

 fact the place where the synthesis of hippuric acid is effected, Bunge 

 and Schmiedeberg determined by direct experiment. They cut out the 

 kidneys from a dog that had been just killed, and passed defibrinated 

 blood, to which benzoic acid and glycocoll had been added, through the 

 renal arteries. It flowed away through the veins of the kidneys and 

 returned through the arteries, this process being continued for several 

 hours. Hippuric acid was then found in this blood as well as in the 

 fluid which flowed from the ureter. The other kidney and a part of 

 the original blood were used as a control, but no hippuric acid was 

 found in them. The surviving kidney had, therefore, produced hippuric 

 acid from glycocoll and benzoic acid. When the experimenters added 

 only benzoic acid, but no glycocoll, they found that the amount of 

 hippuric acid formed was very small. This, however, quickly increased 

 when glycocoll was added and passed through the kidney. The syn- 

 thesis was just as satisfactory at the room- temperature as it was at 

 37 C. 



The red blood-corpuscles and the cells of the kidneys are of great impor- 

 tance in the synthesis of hippuric acid. When the kidney tissues are 

 destroyed by chopping, or, better yet, by rubbing them up with pulverized 

 glass, we find that the conjugation of glycocoll with benzoic acid no longer 

 takes place. When the kidneys are cooled to 20 degrees and then raised 

 to 40 degrees, it is also found that hippuric acid is no longer produced 

 from its components. Again, the synthesis could not be effected if the 

 serum of the blood, instead of the blood itself, was utilized. It has been 

 shown, by the investigations of A. Hoffmann, that oxygen plays an impor- 

 tant part in this synthesis. 1 He led blood through the kidneys, in which 

 the oxygen had been displaced by carbon dioxide, and found that no syn- 

 thesis of hippuric acid resulted. Quinine also prevented the kidney cells 

 from producing hippuric acid. 



It seems very probable that the synthesis of hippuric acid from glycocoll 

 and benzoic acid is due to a ferment, water being split off. The attempt 

 has been made to isolate such a ferment. Recent investigations in 

 which, contrary to earlier experiments, it was found possible to detect 

 the synthesis in the chopped up kidneys, lead to the hope 2 that the 



1 A. Hoffmann: Arch. exp. Path. Pharm. 7, 233 (1877). 



2 W. Kochs: Pfliiger's Arch. 20, 64 (1879). M. R. Berminzone: Bol. accad.med. di 

 Genua 16, No. 1 (1901). J. E. Abelous and H. Ribaut: Compt. rend. Soc. Biol. June 9, 

 1900. 



