252 INFECTION AND RESISTANCE 



one part of serum to 8 or 10 parts of the filtrate will usually elimi- 

 nate all secondary reactions and prove strictly specific. 



An illustration of such an elimination of "partial" or "minor" 

 precipitins by diminution of the amount of the homologous anti- 

 serum is given in the following table taken from the work of Kor- 



ANTICOLI RABBIT SERUM 

 TABLE III 



The precipitating action of the anticoli rabbit serum upon its corresponding 

 filtrates and upon the filtrates of B. N 1 (hog cholera) and B. typhosus. 



Coli filtrate Anticoli aerum 



0.5 c. c. 0.05 Cloudiness in all tubes in 1 hour at 37.5 C. which 



. 5 c. c. . 10 increases rapidly. Six hours well-marked precipita- 



0.5 c. c. 0. 15 tion most copious in tube containing 0.25 serum. 



0.5 c. c. 0.25 Fluid in all tubes becomes clear. 



B. Nl filtrate Anticoli serum 



. 5 c. c. . 10 At 6 hours a slight precipitate in the form of fine 



0.5 c. c. 0.25 granules appears on the sides of the tubes. After 



24 hours the precipitate in the tube containing 

 0.25 c. c. serum compares in amount to that 

 formed in the homologous filtrate with 0.05 c. c. 

 of serum. 



B. typh. (Coll) 



filtrate Anticoli serum 



And, indeed, though the great practical value of the precipitin 

 reaction has not been in the special field of bacteriology, it has been 

 successfully utilized in the diagnosis of glanders by Wladimiroff, 21 

 and constitutes a valuable adjuvant to our methods of determining 

 the biological relationship between micro-organisms. 



The production of precipitins against unformed proteins, egg 

 albumen, animal sera, etc., is much more easily accomplished than 

 the production of bacterial precipitins, and three intravenous injec- 

 tions of from 2 to 5 c. c. of the protein at 5 or 6-day intervals usually 

 give rise to a formation of potent precipitins. When a small quan- 

 tity of the serum of such an animal, taken 9 or 10 days after the 

 third injection, is mixed in a test tube with an equal quantity of a 



20 Norris. Jour, of Inf. Dis., Vol. 1, 1904, p. 472. 



21 Wladimiroff. "Kolle u. Wassermann Handbuch," article on "Glanders/' 

 Vol. 5, 2d Ed. 



