DEVIATION OF COMPLEMENT 



155 



serum. On the other hand, 0-01 c.c. gave the maximum 

 precipitate. 



We have shown above that complement may be fixed by 

 a serum plus its anti-serum even although there be no 

 precipitate. We have accordingly inquired whether in 

 this instance the principle of optimum proportions holds, 

 and have found that this is the case. The following may be 

 taken in illustration : 



Anti-serum, rabbit v. guinea-pig, 0-025 c.c. to each tube. Varying 

 amounts of guinea-pig's serum. 



Test for complement = 0-5 c.c. suspension of ox's corpuscles treated 

 with immune-body. 



TABLE 8 



Guinea- 

 pig's 



Anti- serum Rabbit's complement 



serum 55C ^ x 



c.c. c.c. 0-05 0-1 0-2 0-3 04 c.c. 



0-025 0-1 

 0-025 0-01 

 0-025 0-001 



complete complete complete complete 



complete complete complete 



00 i just complete 



complete 



complete complete complete 



0-025 0-000,1 just 



complete 



0-025 0-000,01 almost complete complete complete complete 

 complete 



In this case also it will be seen that the maximum deviation 

 occurs with 0-001 c.c. serum, whilst above, as well as below, 

 this amount the deviation of complement diminishes. 



It has been recognized by various observers in testing 

 a precipitin (anti-serum) with a given amount of the homo- 

 logous serum, that the precipitate may become less when 

 the amount of serum is increased beyond a certain point, 

 and after a precipitate has formed this may be dissolved 

 on adding homologous serum. For example, with 0-001 c.c. 

 ox's serum and 0-05 c.c. anti-serum a bulky precipitate is 

 obtained, but this is dissolved in great part on the addition 

 of 0- 1 c.c. ox's serum. In this respect also there is an analogy 

 between the phenomena of precipitation and of deviation of 

 complement. We cannot, however, agree with Moreschi 



