2l6 



GENERAL BIOLOGY OF MICRO-ORGANISMS 



assumption, as it has been shown by Bordet that amboceptor 

 does not unite with complement in the absence of antigen. It 

 seems more probable that some other factor, such perhaps as a 

 marked agglutination of the bacteria in the stronger solutions, 

 may serve to protect them from the bacteriolytic action. 



Fixation of Complement.- As has been mentioned, it is pos- 

 sible to produce cytolysins for red blood cells. This is commonly 

 done by injecting the washed blood corpuscles of a sheep (o.i c.c. 

 +0.5 c.c. salt solution) into a rabbit intravenously three or four 

 times at intervals of five days. The serum of the rabbit becomes 



FIG. 88.- 



Illustrating the conception of deviation of complement. 

 b, antigen; k, complement. 



a, Amboceptor; 



strongly hemolytic for sheep's cells. The blood is drawn from 

 the carotid artery, the serum separated, rendered perfectly 

 clear and after heating to 56 C. for 30 minutes is stored in hermet- 

 ically sealed ampoules containing i c.c. each, in a low tempera- 

 ture refrigerator. When this hemolytic amboceptor is diluted to 

 the proper point, which must be ascertained by trial and error, 

 it will just cause the complete hemolysis of a definite quantity 

 of washed sheep's corpuscles (0.2 c.c. of a 5 per cent suspension) 

 when combined with o.i c.c. of a 10 per cent solution of fresh 

 normal serum of a guinea-pig (complement). The mixture of 

 this quantity of the immune serum, which may now be called 

 one unit of hemolytic amboceptor, with 0.2 c.c. of freshly prepared 

 5 per cent suspension of washed sheep's corpuscles produces a 



