ANTI-ENZYME IMMUNITY 191 



from it, in which antibody was 50 to 60 per cent of the total protein. 

 In other parallel experiments, carbohydrate precipitation determinations 

 were studied with antibody solution alone, and with antibody solu- 

 tion to which an equal volume of normal horse serum had been added. 

 The non-specific protein had no effect upon the amount of antibody 

 nitrogen precipitated under any conditions of temperature investigated. 



e. Failure of Agglutinated Bacteria to Adsorb Non-Specific 

 Proteins. Heidelberger and Kabat (1934, 1936, 1937) investigated the 

 question as to whether non-specific proteins were adsorbed on bacteria 

 in an agglutinating system. They found that the amount of antibody 

 nitrogen taken out by the bacterial after 48 hours at 0°, with occasional 

 stirring, was independent of the volume just as in the precipitation 

 reaction. Thus the antibody nitrogen removed by agglutination was 

 independent of the concentration of antibody nitrogen in the super- 

 natant. 



Pneumococcal cells (Type I), agglutinated with a considerable ex- 

 cess of antiserum, were washed with saline until the supernatant con- 

 tained no agglutinin. The cells agglutinated in the region of excess 

 antibody, they believed, would still have available on the surface of 

 the particles some of the specifically reactive groupings of the originally 

 multivalent antibody. These particles, then, should be able to combine 

 with Type 1 pneumococcal carbohydrate on the surface of freshly 

 added unsensitized Type I pneumococcal cells, and reagglutination 

 should take place to form larger aggregates. This assumption was veri- 

 fied and the effect was found to be specific, since it was not given by 

 pneumococcal Types II or III, or by Type I R cells under identical con- 

 ditions of salt concentration. Reagglutination was, moreover, produced 

 almost as completely by suitable amounts of Type I carbohydrate in 

 solution, so that the conclusion appeared inescapable that these par- 

 ticulations, as well as the original antigen-antibody combination, were 

 a chemical, and not a non-specific adsorption process. 



While the finely and uniformly resuspended pneumococcus-agglu- 

 tinin complex was found to reagglutinate completely with the addition 

 of 0.01 mg. and partially with 0.0001 mg. of Type I pneumococcal 

 polysaccharide, no visible reaction was observed with 0.1 mg. of Type 

 II pneumococcal polysaccharide. When the upper fluid containing the 

 Type II cells in suspension was decanted away from the mass of the 

 Type I pneumococcus-antibody agglutinate, and the decanted suspen- 



