1911.] 



On the Factors Concerned in Agglutination. 



the agglutination is removed from solution. It has also been shown that a 

 precipitate is formed in a mixture of laked corpuscles, antibody, and middle- 

 piece. This suggests that the substance present in the middle-piece solution 

 is actually precipitated on the sensitised corpuscles and that such precipitation 

 is a part of the mechanism of agglutination. 



It was decided to examine the effect of adding middle-piece solution to a 



Table VI. 





3 «.e. of 



+ 3 c.c. antiserum, 

 rabbit v. horse, diluted 

 1 in 10. 



+ 3 c.c. antiserum, 

 rabbit v. horse, diluted 

 1 in 100. 



+ 3c 

 saline 



c. normal 

 solution. 





serum 

 (antigen) 

 diluted. 



(A) 

 + 3 c.c. 

 normal 



'(«) 



middle-piece 

 1 in 10. 



(B) 

 + 3 c.c. 

 normal 

 saline. 



middle-piece 

 1 in 10. 



(0). 

 saline. 



to 

 + 3 c.c. 

 middle-piece 

 1 in 10. 



1 



2 



3 



4 

 5 

 6 



I 



9 



1 in 5 



1 in 10 



1 in 20 



1 in 40 

 lin 80 

 1 in 160 



1 in 320 

 1 in 640 

 1 in 1280 



precipitate 



Precipitate 

 Turbidity 



Large 

 precipitate 



Precipitate 

 Turbidity 



Clear 



Very slight 

 opalescence 



Clear 



" 



Clear 



Opalescence 



Marked 

 turbidity 



Opalescence 



Slight 

 opalescence 



Clear 



Clear 



10 



Controls. 



3c.c. 



saline 

 solution 





Clear 



Clear 



Clear 



Clear 



Clear 



All the tubes contained 9 c.c. The tubes numbered 1 to 9 in each column contained various 

 dilutions of normal horse serum (antigen). To the tubes in column A were added 3 c.c. of 

 normal saline solution and 3 c.c. of antiserum in a dilution of 1 in 10. To the tubes in row a 

 were added 3 c.c. of a middle-piece solution (1 in 10) and 3 c.c. of antiserum 1 in 10. A bulky 

 precipitate was formed in the tubes of column A and of column a. There was no difference in 

 the appearance of the tubes in column A and in the tubes in column a. To the tubes in column B 

 were added 3 c.c. of normal saline and 3 c.c. of antiserum diluted 1 in 100. To the tubes in 

 column b were added 3 c.c. of middle-piece solution 1 in 10 and 3 c.c. of antiserum diluted 

 1 in 100. This dilution of antiserum produced a rather doubtful opalescence in tubes 2 and 3 of 

 column B. The remaining tubes of column B were clear. A very distinct difference existed 

 between the tubes in column B and the tubes in column b. In the tubes in column b opalescence 

 or turbidity was distinctly visible in tubes 2 to 6. The tubes in column C contained horse serum 

 only. The tubes in column c contained horse serum and middle-piece. No precipitate was 

 produced by this mixture. The tubes marked 10 in the various columns show that neither anti- 

 serum alone nor antiserum and middle-piece solution produced a precipitate. 



It will be noticed that the tubes 1 in columns B and b showed no opalescence. This inhibitory 

 effect is due to relative excess of antigen. 



The tubes were incubated for 4 hours at 37° C, and then allowed to stand overnight in the 



