542 INFECTION AND RESISTANCE 



gold solution and 7 c.c. of the 2 per cent, potassium carbonate solu- 

 tion are added. The solution should remain perfectly clear. At 

 80 C. while stirring with a clean thermometer, 10 drops of oxalic 

 acid are slowly added. The solution may now turn a delicate bluish- 

 pink, often due to an excess of alkali. Otherwise the solution re- 

 mains colorless until 90 C. has been reached. When 90 C. has been 

 reached, the gas is turned out and, while stirring, 5 c. c. of 1 per cent, 

 formaldehyde is added, drop by drop. If a pink color makes its 

 appearance before all the reducing agent has been added, Miller 

 advises to stop at once. He also states that the best solutions are 

 those in which the color change is slow. For further technical points, 

 the reader is referred to the paper of Miller and his collaborator in 

 the Johns Hopkins Hospital Bulletin, 1915, xxvi, 391, from which 

 this description is almost bodily taken. 



The test is done as follows: into a clean test tube 1.8 c. c. of 

 fresh sterile 0.4 per cent. NaCl solution is placed. Into ten further 

 tubes 1.8 c. c. of the same salt solution is placed. To the first tube is 

 added 0.2 c. c. of spinal fluid to be tested and well mixed. 1 c. c, of 

 this 1 :10 solution is added to the second tube, mixed, and of this 1 c. c. 

 is added to the third tube, in consequence of which dilutions are ob- 

 tained running from 1:10, 1:20, 1:50. Now to each of these is 

 added 1 c. c. of the colloidal gold solution. Changes begin to take 

 place in five minutes, which usually reach their completion in about 

 a half hour. The spinal fluids must be free from blood and clear 

 from bacterial contamination. 



Normal spinal fluids produce usually no reaction. The so-called 

 luetic curve is usually one in which the greatest precipitation occurs 

 in the tubes ending in 1 :40 to 1 :160. In suppurative lesions, etc., 

 the strongest precipitation occurs in higher dilutions, say, from 320 

 to 280, which Lange has called "verschiebung nach oben." A so- 

 called paretic curve means complete precipitation in, say, from 110 

 to 160, with a gradual fading out toward the higher dilutions. A 

 complete precipitation means a colorless tube; partial precipitation 

 shades from pale blue to the complete red of the unaffected colloidal 

 gold. Fluids from early stages of syphilis without nervous system 

 involvement react usually like normal fluids. 



That the reaction has unquestionably found a permanent useful- 

 ness cannot be doubted. It seems to be dependent entirely upon 

 the technique of making the colloidal gold solution. 



