398 



Mr. W. W. C. Topley. 



M.H.D. of Hemolysin ... = 0"05 c.c. of a 1/250 dilution. 

 M.H.D. of Complement ... = 03 c.c. 



Amount of Test Corpuscles = 0"05 c.c. of a 50-per-cent. suspension. 



Haemolysis in 1 hour at 37° C. 



M.H.D. 

 complement. 



1. 



i. 



1. 



1. 



1. 



2-5. 



lz 



5. 



10. 



M.H.D. 



haemolysin. 



1. 



2-5. 



5. 



10. 



100. 



1. 







1. 



1.. 



Salt concentra- 

 tion — ■ 

 '8 per cent. 



Complete 



Complete 



Complete 



Complete 



Complete 



Complete 



Complete 



Complete 



1-0 „ 

 1 -2 

 1 -4 



Almost 

 complete 



Slight 

 None 



-„ 

 Almost 

 complete 



None 



„ 

 » 



Almost 

 complete 



33 

 33 



Almost 

 complete 



» 



Almost 

 complete 



Slight 



33 



Very 

 marked 



Moderate 



33 



"Very 

 marked 



1 -6 „ 



)» 





None 





None 



Slight 



Moderate 



1 -8 



>? 







None 







None 



Slight 



2 -0 







33 











None 



2-2 



j) 



33 





33 



Marked 





33 





2 4 „ 











Slight 





33 



» 



2 6 



» 



33 





33 



Trace 





33 



33 



2-8 „ 











None 







33 



Note. — The two series are not strictly comparable, because, while it was always possible to add the 

 doses of haemolysin as 05 c.c. of a saline dilution, the amount of complement added necessarily varied. 

 The last series was the only one in which the amount added was sufficiently large to seriously influence 

 the salt concentration, and here the values, instead of varying from - 8 to 2 "8 per cent., ranged 

 approximately from - 8 to 2 '38 per cent. In the series containing 100 M.H.D. of haemolysin, the tubes 

 which showed little or no haemolysis showed marked agglutination of the red cells ; but this also 

 decreased, and finally disappeared as the saline concentration increased. 



Having thus confirmed Markl's observation that increased saline con- 

 centration inhibits the combination of the complement with the sensitised 

 red cells, and, further, that this inhibitory influence can, to a certain extent, 

 be counterbalanced by increasing the amount of hsemolytic antibody present, 

 it was natural to attempt to determine whether, in hypotonic solutions, the 

 amount of antibody necessary to cause lysis would be decreased ; and, finally, 

 whether it was possible for Complement to combine with red cells without 

 the intervention of hemolytic antibody in mixtures containing little or no 

 ionisable salt. 



