SOURCES OF ERROR (iN THE PROCESS) 197 



reacts not only with albumen and albuminous 

 decomposites, but under certain conditions with other 

 compounds as well, for instance, sugar. 20 No trouble 

 can be caused by these, if distilled water be used. 

 The organ cannot give off any non-albuminous sub- 

 stances, which will affect the reaction of the fluid, if it 

 is boiled in the manner prescribed. There could not 

 possibly be any carbohydrates left, and we have the 

 control test with serum to fall back on, in any case. 

 Were this to contain much sugar, and, in conse- 

 quence, to interfere with the reaction of the outer 

 fluid, then it is conceivable that a coloration might 

 take place, which could not be referred to albuminous 

 decomposites. This result, however, would appear in 

 the test with serum alone, and also in the one with 

 serum substrate. Even the blood serum from 

 cases of diabetes does not show any positive reaction 

 ascribable to the presence of sugar. Non-compliance 

 with the directions respecting water generally mani- 

 fests itself in the fact, that a really positive reaction 

 turns out negative ; the reaction being, in fact, very 

 sensitive towards acids and alkalies, i.e., towards H 

 and OH ions. 



For the reasons laid down we must always boil 



j 



the organs in distilled water, and preserve them, as 



20 Vgl. \V. Halle, E. Loewenstein und E. Pribram : 

 " Bemerkungen iiber Farbreaktionen des Triketohydrinden- 

 hydrats (Ninhydrin), 3 ' Biochem. Zeitschr., lv, 357. 1913. 



