128 THE ROYAL SOCIETY OF CANADA 



Oils, saline or dilute glycerol "solutions" of reductase; (d) injecting 

 surviving organs with the Prussian blue and gelatine mixture; (e) 

 perfusing this injection mass or, for instance, ferric chloride through 

 the vascular system of a surviving organ; (f) perfusing the blood- 

 vessels and obtaining in the case of the kidney, artificial urine, in the 

 case of the liver, artificial bile. 



As might be expected, the method merely of immersing pieces of 

 tissue was by far the most unsatisfactory. No good results, com- 

 parable with those of Dr. Vernon" in the case of oxidase, were ob- 

 tained; but in this respect reductase resembles glycogenase, an un- 

 doubted endo-enzyme. 



The routine method followed was to use the press-juice from 

 a Klein's press. This was kept sterile under toluene. Its reducing 

 power gradually declined in energy, until at the end of three months 

 it had vanished. 



Various extracts of organs were made — aqueous, saline and 

 glycercl — but as their reducing power was considerably weaker than 

 that of press-juice, these were not so extensively used in examining 

 the properties of reductase. 



Injection of the Prussian blue and gelatine mixture into the blood 

 vessels of organs was not used on many occasions. It was, however, 

 originally by this method that my attention was drawn to tissue re- 

 duction, as I suspected that the "fading" of the mixture in the capil- 

 laries of the parenchyma of liver and kidney was chemically of the 

 nature of a reduction. This does not constitute a convenient method 

 owing to the liability of the gelatine to "set" if the proper temperature 

 is not maintained. 



The revival of the blue colour in an injected and almost color- 

 less kidney or liver cut open and exposed to the air or to the action 

 of HjOj is striking when seen for the first time. The vessels on the 

 cut surface begin to show up like letters written in "sympathetic" ink. 



It was by this method that I obtained an artificial, gelatinous leuco 

 urine from the sheep's ureter; it became blue on treatment with H2O2. 



The method of injecting ferric chloride through the portal system 

 and examining both the hepatic emergent fluid and the contents of 

 the gall-bladder for ferrous chloride, in both of which it was found, 

 proved a satisfactory method. 



IV. Preparation of the Juice. 



The following may be taken as typical of the technique. A liver 

 removed from the animal (rabbit, cat, dog, pig) before the heat has 

 left it, is perfused through the portal vein with tap water at 40°C. 



