1909.] " Absorption " of Specific Agglutinins hy Bacteria, etc. 171 



Table 1. 



Tube. 



0 'o5-per-cent. 

 K^aClj m c.c. 



Diluted aggluti- 

 natiug serum, 

 in c.c. 



standardised 

 killed bouillon 

 culture, in c.c. 



1 



0 0 



1 -0 



1 -5 



2 



0-2 



0-8 



1 5 



3 



0 -4 



0-6 



1 -5 



4 



0 u 



0-5 



1 -5 



5 



0-6 



0-4 



1 -5 



6 



0-65 



0-35 



1 -5 



7 



0-7 



0-3 



1 -5 



8 



0-75 



0-25 



1 -5 



9 



0-8 



0-2 



1 -5 



10 



0-83 



0 17 



1 -5 



11 



0-87 



0 13 



1 -5 



12 



0-9 



0-1 



1 o 



13 



1 -0 



0 0 



1-5 



Each series of tubes thus contains quantities of agglutinating serum or 

 other fluid to be tested, diminishing from 1 c.c. to O'l c.c. Tube 13 acting as a 

 control to ensure the absence of spontaneous agglutination. 



As soon as all these measurements were completed the tubes were shaken 

 from right to left, care being exercised not to carry fluid from one tube to 

 the other. They were then placed in a water bath at 37° C. for two hours, 

 taken out, allowed to cool down to room temperature (which takes about 

 a quarter of an hour), and examined for agglutination. Thereafter they 

 stood a further 20 to 24 hours at room temperature and were again 

 examined. 



"When the agglutinating powers of several sera are to be examined, a 

 similar series of 13 test-tubes is set up for each. The actual measurement 

 of the agglutination that has taken place is made as follows : — From the 

 whole number of tubes set up as above described, that one is selected which 

 shows the minimum amount of agglutination definitely visible to the naked 

 eye. This tube is called the " standard " tube, and it is carefully compared 

 with those tubes in each of the other series which show nearly similar 

 degrees of agglutination. In this way one is able either to pick out in 

 each series a tube showing the same degree of agglutination as the standard, 

 or to estimate by visual inspection the situation that such a tube should 

 occupy between one tube showing a greater degree of agglutination and 

 the next tube in the series showing a less degree of agglutination than the 

 standard tube. 



Taking the reciprocal figure of the actual amount of diluted serum added 

 to the tube giving the same degree of agglutination as the standard tube, 

 and multiplying this figure by the number of times the serum was diluted, 



