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Mr. W. W. C. Topley. 



by complement alone in salt-free media with that produced by a specific 

 haemolysin in normal saline. 



The dilution of a complementary serum with 10 times its volume of 

 7'8-per-cent. saccharose solution, and the subsequent incubation of the 

 mixture for one hour at 37° C, destroys the activity of the complement, but, 

 if we add 0'075 c.c. of complement to 1 c.c. of 7'8-per-cent. saccharose 

 solution, containing - 05 c.c. of a 50-per-cent. suspension of sheep corpuscles, 

 and then incubate at 37° C. for one hour, we shall obtain a more or less 

 marked degree of haemolysis. This can only mean that the complement 

 which has become attached to the red cells is no longer subject to the 

 destructive action of the salt-free medium. Thus, it is clear that the 

 addition of a haemolytic serum will only tend to increase haemolysis, if the 

 increased tendency to combination of red cells and complement, caused by 

 the haemolytic antibody it contains, is greater than the decreased tendency 

 to combination resulting from the increased saline concentration. For 

 unless combination is fairly rapid the destructive action of the markedly 

 hypotonic medium on the complement will come into play. It follows that 

 we should expect very powerful haemolytic sera to increase lysis under these 

 conditions, and weak ones to decrease it. 



In general, the active sera, which are obtained by immunising rabbits 

 against sheep corpuscles, tend to markedly increase haemolysis in saccharose 

 solutions ; but this is not always the case, a,nd in some experiments it was 

 found that more lysis occurred with complement alone than with complement 

 and haemolysin, thus confirming the observation of Sachs and Terruuchi. 

 The addition of serum, or serum diluted with saline, seems always to act 

 more powerfully in inhibiting haemolysis in salt-free media than does the 

 addition of an equal amount of normal saline solution alone ; and, although 

 the haemolytic sera here employed were always greatly diluted, it is possible 

 that this factor came into play. 



Keeping these facts in mind we may pass to the consideration of experi- 

 ments in which varying amounts of haemolysin were allowed to act in vary- 

 ing strengths of saline in 7"8-per-cent. saccharose solution, in the presence of 

 0"05 c.c. of a 50-per-cent. suspension of sheep corpuscles and - 05 c.c. of 

 complementary serum. 



Experiment. — Each tube contained 1 c.c. of 7'8-per-cent. saccharose solution 

 to which had been added varying amounts of sodium chloride. To each tube 

 was added - 05 c.c. of a 50-per-cent. suspension of sheep corpuscles and 

 0*05 c.c. complement. To each tube was then further added the amount 

 of haemolysin indicated in the left-hand column. This haemolysin was added 

 as 0"05 c.c. of a dilution of the required strength in the saline-saccharose 

 solution. Incubation was carried out for 1 hour at 37° C. 



