H8 PROPERTIES OF ANTI-SERUM TO SERUM 



tested for in the usual way. The result in both series was 

 negative, i.e. the molecules which fix complement were prac- 

 tically all in the precipitate. In another experiment with 

 0-01 c.c. ox's serum and 0-025 c.c. anti-serum, performed in 

 the same way, we found that the supernatant fluid deviated 

 about one-twelfth of a haemolytic dose of guinea-pig's 

 complement an exceedingly small amount. So also in the 

 case of anti-human serum we found that the precipitate 

 obtained by mixing 0-1 c.c. of human serum with 1 c.c. of 

 the anti-serum in 5 c.c. of salt solution, possessed ex- 

 clusively the deviating power, the separated fluid being 

 practically without any effect when tested. These re- 

 sults are in harmony with those obtained by Gay on this 

 point. 



We may also add that there is no question of complement 

 being carried down mechanically by the precipitate in 

 process of formation. The precipitate after it has formed 

 may be repeatedly washed and still retains the property of 

 fixing complement. 



Observations on the relation between precipitate formed 

 and the deviating power show that the amounts are not 

 strictly proportional. For example, using 0-025 c.c. of anti-ox 

 serum along with varying amounts (0-1, 0-01 c.c. &c.) of ox's 

 serum, we found that the maximum deviation of comple- 

 ment was given by 0-001 c.c., whilst distinctly the greatest 

 amount of precipitate was given by 0-01 c.c. Again, on 

 using the same quantity of serum, viz. 0-001 c.c. and varying 

 the amounts of anti-serum, we found that a much greater 

 amount of precipitate was given by 0-3 c.c. of anti-serum 

 than by 0- 1 c.c., whilst the amount of complement fixed was 

 practically the same in the two cases. Further details on 

 this point are given below under Section 6. It is also 

 interesting to note that Friedberger and Liefmann have 

 found that it is possible by heating to deprive an anti- 

 serum of its precipitating action while its power of fixing 



