188 



Dr. G. Dreyer and Mr. J. S. 0. Douglas. [Nov. 16, 



used, but in the case of a polyvalent serum only one race of the homologous 

 bacteria was tried, the standardised test emulsion being in every case made of 

 the same strain of bacteiia as had been used for absorbing the agglutinins. 



In every experiment, the volume of the bacterial emulsion was kept 

 constant (4 c.c), and allowed to act on a constant volume (4 c.c.) of the 

 agglutinating serum in various dilutions. If volumes other than these were 

 used, the fact will be found stated in the tables appended to this paper. 



After mixing the bacterial emulsion, to be used for absorption, with the 

 various dilutions of serum to be acted on, the tubes were immediately shaken, 

 corked, and placed in a water bath at 37° C. for two hours, being shaken up 

 again at the end of each hour. The tubes were then centrifugal ised, and the 

 supernatant fluid tested for the strength of its agglutinin content as described 

 in the previous paper. 



In some cases it was of importance to estimate a quantity of agglutinin less 

 than one unit, and this was easily efTected by substituting a part of the 

 saline in each tube in the titration by a constant known fraction of a unit of 

 agglutinin, obtained by dilution of the original serum, without altering the 

 total volume in the tube. This method enabled us to determine quantities as 

 small as nearly 0-4 unit. All values of agglutinin ai'e expressed in arbitrary 

 units as exphained in the former paper. 



Tlirougliout our paper the following terms are used : — 



T = the total number of units which the given dilution of serum contained 

 before absorption. 



B = the numl)cr of units left free in the supernatant fluid after absorption 

 has taken place. 



C = T minus B, i.e. the number of units removed from the original solution 

 by the absorbing matter. 



From the following doscrii)tion of our experiments, it will be clearly seen 

 tliat our results are absolutely contradictory to the statements of Arrhenius 

 on nearly every point, and we will therefore discuss in the light of our 

 experiments eacli of the arguments summarised aljove and brought forward 

 by that gifted cliemist and niiithematician in support of his theory tliat the 

 interaction of bact(!iia and iigglutinin can be expressed by the formula 



1. In another pa])er* we have fully proved that in the al)sor])tion of 

 agglutinin by bactei'ia a, consid(!i'al)le tinu; cla])ses before equilibrium is 



* (I. Dicyer and .1. S. ( '. Douglas, "Tlii; Velocity of Keaction in the 'Absolution' of 

 Specific AgKlutinins by Bacteria, and in the 'Adsorption' of Agglutinins, Trypsin, and 

 Sulphuric Acid hy Animal (Jharcoal," Ki'/ini, y>. 108. . 



