PRACTICAL APPLICATIONS 323 



reaction practically always means a true meningitis; a negative reaction 

 usually means " serous meningitis," with a much better prognosis if the 

 underlying cause is corrected. 



Noguchi has found the test positive in about 90 per cent, of cases of 

 general paralysis and in 60 per cent, of cases of locomotor ataxia or cere- 

 bral or spinal syphilis. In the diagnosis of syphilis the Wassermann 

 reaction with cerebrospinal fluid has greater value than the protein re- 

 action. However, the best results in diagnosis are usually secured by a 

 Wassermann test, butyric-acid test, and total and differential cell-counts. 

 In a case where the diagnosis rests between tuberculous meningitis and 

 syphilis, a positive butyric-acid test and a negative Wassermann reaction 

 would decide in favor of the former. 



The test is extremely simple. Into a small, thin-walled test-tube 

 place 0.2 c.c. of cerebrospinal fluid (which must be clear and free from 

 blood) ; add 1 c.c. of a 10 per cent, solution of butyric acid in normal salt 

 solution; heat over a low flame and boil for a short period. Then add 

 quickly 0.2 c.c. of a normal solution of sodium hydroxid and boil once 

 more for a few seconds. The presence of an increased content of protein 

 is indicated by the appearance of a granular or flocculent precipitate, 

 which gradually settles to the bottom qf the tube, under a clear super- 

 natant fluid (Fig. 88). 



The velocity and intensity of the reaction vary with the quantity of 

 the protein contained in a given specimen. The granular precipitate 

 appears within a few minutes in a specimen containing a considerable 

 increase in protein, whereas one hour may be required to obtain a dis- 

 tinct reaction in specimens weaker in protein. In obtaining the reaction, 

 the time period should not be greater than two hours. A faint opales- 

 cence without the frrwotion of a distinct precipitate is to be regarded as 

 within the limits of the normal. 



McDonagh "Gel" Test. McDonagh 1 has recently advocated what 

 he has designated a "gel" test for the diagnosis of syphilis. Clear and 

 blood-free sera are employed, and it is necessary to include a known posi- 

 tive and negative serum each time the tests are conducted. Into each 

 of three dry tubes place 2, 3, and 4 drops of serum, respectively; add 0.1 

 c.c. of acetic anhydrid and 1 c.c. of glacial acetic acid; the tubes are now 

 well shaken and a drop of a saturated watery solution of ammonium 

 sulphate added. Instead of acetic anhydrid and solution of ammonium 

 sulphate the test may be conducted with 0.2 c.c. of a saturated solution 

 of lanthanum sulphate, thorium sulphate, or thorium nitrate in glacial 

 acetic acid. A preliminary reading may be made and a final reading 

 1 Brit. Jour, of Dermat., 1916, April- June, 114. 



