334 UNIVERSITY OF COLORADO STUDIES 



liardt, von Noorden, all made important contributions confirming the 

 value of this reaction both as a diagnostic and a prognostic agent in 

 typhoid fever, and especially in tuberculosis. Fisher found the re- 

 action constantly in measles and rarely in pneumonia. Brecht states 

 that if the reaction appears in pneumonia it is to be regarded as of 

 orave signiticance. Goldschmidt found the reaction constantly in 

 miliary tuberculosis and typhoid fever. Brewing found this reaction 

 of great value as a diagnostic and prognostic agent in puerperal 

 fever and concealed septic processes, as well as in typhoid fever and 

 tuberculosis. In surgical tuberculous affections, Pape found that 

 after every operation the reaction which had been previously present 

 disappeared, usually within three to five days. Warthin and Simon 

 both emphasized the importance of the color of the foam in making 

 the test, and found it of great value in the diagnosis of typhoid fever 

 and the prognosis of tuberculosis. Kessel considers the reaction of 

 great aid in diagnosing typhoid fever in children. Michaelis especi- 

 ally emphasized the value of the test in the prognosis of tubercu- 

 losis. He also found this reaction to be very constant in measles, 

 and strikingly infrequent in German measles. 



Notwithstanding the fact that a great mass of convincing 

 evidence has been collected during the past seventeen years as to the 

 value of the Ehrlich diazo reaction, especially as to the diagnosis of 

 typhoid fever and the prognosis of tuberculosis, it is remarkable that 

 the great majority of practising physicians in this country are not 

 familiar with the reaction, and never make use of it in diagnosis or 

 prognosis of disease. 



The Ehrlich diazo reaction, like so many of our useful clinical 

 tests — the tests for indicau, bile, sugar, hydrochloric acid, lactic acid 

 — is a color reaction, and depends upon the production of dyes by the 

 chemical union of suitable organic substances with a diazo compound. 



In carrying out this test the reagent is prepared according to the 

 formulae recommended by Ehrlich. We require two solutions, which 

 are termed respectively solutions I. and II. 



