34 PROPERTIES OP H^EMOLYTIC SERA 



ON THE SEPARATION OF IMMUNE-BODY AFTER 

 SATURATION WITH COMPLEMENT 



If immune-body forms, as Ehrlich believes, a link between 

 the receptor of the red corpuscle and complement, then 

 seeing that complement is not separable after combination, 

 saturation with complement should lead to the locking-up 

 of the molecules of immune-body so that they can no 

 longer be separated. Various experiments have been 

 carried out in order to test whether this is the case, and 

 these show that immune-body is still recoverable after the 

 treatment with complement. To take an example : 

 nine doses of immune-body are added to 1 c.c. of suspension 

 of red corpuscles, and after time is allowed for combination 

 they are centrifugalized ; the fluid is pipetted off, and they 

 are washed several times in salt solution. To the sensitized 

 corpuscles there is added a considerable excess of comple- 

 ment ; that is, more than will be taken up through the 

 medium of the immune-body ; the tube is then put in the 

 incubator for two hours at 37, and then to the clear fluid 

 we add 1 c.c. of untreated corpuscles. It is found that 

 complete lysis of these takes place. In spite, therefore, of 

 the saturation with complement, sufficient immune-body for 

 lysis has been obtained by dissociation. We can modify 

 this experiment as follows : After the sensitized corpuscles 

 have been treated for two hours with excess of complement, 

 we can remove this excess by adding a quantity of bacterial 

 emulsion (say, of v. Metchnikovi) treated with its corre- 

 sponding immune-body. This will absorb the complement 

 left free, and accordingly when fresh corpuscles are then 

 added no lysis occurs, but if thereafter they be separated 

 by centrifugalization and washed in salt solution, and 

 then complement is added, lysis occurs. This result shows, 

 as before, that they have obtained immune-body by dis- 

 sociation. (In these experiments the guinea-pig's serum 



