300 the role of agglutination in immunity, 



The So-called Chemical Agglutination. 



Although chemical agglutination, i.e., clumping b}^ means of 

 definite chemical substances, such as vesuvin, formaldehyde, can 

 have little, if any, bearing upon immunity, yet as the subject was 

 interesting, experiments were made to determine the behaviour 

 of washed leucocytes towards bacteria so agglutinated. I have 

 already^ pointed out that many of the chemical agglutinants 

 produce a precipitate when added to nutrient bouillon, and that 

 the agglutination is probably due to the flocculation of this pre- 

 cipitate which has formed upon the surface of the cells. Since it 

 occurs with bouillon, it may also occur with the traces of bouillon 

 adhering to the bacteria which have been grown upon nutrient 

 agar, so that the chemical agglutination of bacteria suspended in 

 normal saline may be caused by the formation of the precipitate 

 in an exceedingly thin film upon the bacteria and the subsequent 

 flocculation of the films. 



In the following experiments cells from a 48 hours' nutrient 

 agar culture of the Jenner Institute race were suspended in normal 

 saline and filtered through paper. Quantities were pipetted 

 into small test-tubes, and to each an equal volume of a solution 

 of the chemical agglutinating substance was added. Agglutina- 

 tion or precipitation was decided with formalin, alcohol and 

 vesuvin, but not with the others. The tubes were centrifuged 

 and the sediment washed with and finally suspended in normal 

 saline. 



Equal volumes of suspension of Bact. typhi in pi.orv^^T-f^c,;o 



normal saline and ^ '' 



Vesuvin, 0*1% . Negative. 



Mercuric chloride, 0-07% ; ,, 



Saffranin, 0-1% i „ 



Formalin (commercial) ... ... .. ... ... ,, 



Alcohol (absolute) ... ... ... ... ... ... ,, 



Hydrochloric acid (0-5 mgrm. HCl to 1 c.c. of suspen- 

 sion ,, 



Control 1 ,, 



These Proceedings, 1900, 82. 



