SOURCES OF ERROR (IX THE PROCESS) 



Tubes must be tested a^ain about every four weeks. 



O - 



Should any error in diagnosis have occurred before 

 this time, and other possible errors have been ex- 

 cluded, then the tubes must be immediately tested for 

 permeability to albumen and for even permeability 

 to peptones. 



(2) Serum. Here we have to deal only with its 

 age, the possibility of an infection, haemolysis, and 

 the contents of the serum in respect of red blood 

 corpuscles and of other form-elements. (See 



pp. 173-175-) 



(3) The Organ. --This is nearly always the cause 

 -.of errors in diagnosis. It is nearly always forgotten 



o r? 



that, in the arrangement and execution of the experi- 

 ment, we are dealing with quantitative conditions. 

 Two cases have to be distinguished :- 



(a) The Biuret Reaction.- -The serum alone dors 

 not give off substances which diffuse and produce a 

 biuret reaction ; so that, as regards compounds which 

 give a biuret reaction, it must be reckoned as com- 

 pletely indifferent. It is comparatively easy to boil 

 the organ in such a way, that the water in which it was 

 boiled will not sfive any biuret reaction. If the ninhv- 



O . ^ 



drin reaction turns out negative, one can never obtain a 

 biuret reaction. If such an organ be mixed with serum, 

 and the dialysate now gives a positive biuret reaction, 

 then we may be sure that decomposition has taken 

 place. The conditions here are very simple. 



