THE TECHNIQUE OF SERUM REACTIONS 255 



use. It is then filtered clear, either through paper, or through a Buchner 

 or Nutsche filter. Berkefeld filters may also be used. The solution is 

 then diluted until the addition of concentrated HNO 3 produces only a 

 slight even turbidity. Before use the reaction of the meat extract 

 should be tested, and if necessary adjusted to neutrality or slight acidity 

 or alkalinity. 



In the actual test with bacterial filtrate, the procedure is as follows: 

 In a series of narrow test tubes, the following mixtures are made: 



Tube 1. Antibacterial serum .5 c.c. + bacterial filtrate 1. c.c. 

 " 2. Normal serum .5 c.c. + bacterial filtrate 1. c.c. 



" 3. Antibacterial serum .5 c.c. + salt solution 1. c.c. 

 " 4. Salt solution .5 c.c. + bacterial filtrate 1. c.c. 



Place the tubes in the incubator at 37.5 C. Tube 1 only should 

 .show a haziness which develops into distinct cloudiness or a flocculent 

 precipitate within one hour. Tubes 2, 3, and 4 should remain clear. 



In testing an unknown protein with serum of an animal immunized 

 with the protein sought for, the technique of the test is as follows: 



1. 0.1 c.c. immune serum + 2 c.c. unknown protein solution. 



2. 0.1 c.c. immune serum + 2 c.c. known protein solution of variety suspected 



(similarly diluted). 



3. 0.1 c.c. immune serum + 2 c.c. protein solution of different nature (similarly 



diluted). 



4. 0.1 c.c. immune serum + 2 c.c. salt solution. 



5. 2 c.c. unknown protein solution. 



If the test is positive a precipitate appears in tubes 1 and 2, but not 

 in any of the others. The precipitate should appear within 15 to 20 

 minutes. 



Bactericidal and Bacteriolytic Tests. The bactericidal and bac- 

 teriolytic powers of serum may be tested either in the animal body or 

 in the test tube. The in vivo test is known as Pfeiffer's phenomenon. 

 This depends upon the fact that bacteria, when injected into the peri- 

 toneal cavity of a guinea-pig, together with a homologous immune 

 serum, undergo dissolution. 



As practiced, the test finds a double application. It may be done to 

 determine the bacteriolytic power of a given serum against a known 

 microorganism, or for the identification of a particular microorganism 

 by means of its susceptibility to lysis in a known immune serum. 



1. Determination of the bacteriolytic power of serum against a known 

 microorganism in vivo: 1 



1 P. Th. Mutter, "Technik d. serodiagnos. Methoden," Jena, 1909. 



