COMPLEMENTS 357 



examined to ascertain the degree of changes undergone by the vibrios. 

 Or the changes may be observed in hanging-drop preparations. -In 

 either case a control is prepared of the culture which has also been 

 incubated along with the mixtures. Gay and Ayer found that 0.02 c.c. 

 of normal human serum contained sufficient complement to effect com- 

 plete lysis of this dose of vibrios even 0.001 c.c. produced distinct 

 changes. 



