434 STUDIES IN IMMUNITY. 



same way as it prevents the adhesion of the particles of barium 

 sulphate to one another or to suspended substances like corpuscles 

 or to colloidal substances like gum arabic.* 



It is evident that this inhibition of hemolysis by citrate is not due 

 to a destruction of the biological hemolysins by this salt, inasmuch 

 as we find they can be reactivated by the addition of an electrolyte. 

 In the same way that we increased the adhesive properties of 

 citrated barium sulphate on the addition of sodium chloride and 

 calcium chloride so that the particles of the complex are able to 

 adhere to one another and flock out, or to adhere to other elements 

 and agglutinate them, so, on adding calcium chloride, we are able 

 to reactivate the biological hemolysins in a citrated medium. In 

 certain instances, as, for example, with venom, this reactivation may 

 be produced by NaCl. If the hemolysis of guinea-pig corpuscles 

 by cobra venom is prevented in a sugar medium by a sufficient 

 amount of citrate, the inhibition may be removed by adding a small 

 amount of sodium chlorid to the mixture. 



It might well be, however, that citrate prevents the action of the 

 biological hemolysins by neutralizing the calcium salts which are 

 necessary for their action. Such an interpretation would seem all 

 the more admissible inasmuch as with certain of these hemolysins 

 (venom, lecithid and alexin) the dissolution of the corpuscles is 

 also lacking when oxalate or fluoride of sodium is added to the 

 mixture. Inasmuch as it is generally supposed that the inhibition 

 of coagulation of the blood and of milk, produced by these salts, is 

 due to a neutralization of the calcium salts, it may well be supposed 

 that the similar inhibition of hemolysis is due to the same 

 reason. 



Such a hypothesis, however, is not justified. In the first place 

 we have to note that although citrate of sodium prevents hemolysis 

 by eel serum, oxalate produces no such effect even when large 

 amounts of iso tonic oxalate solution are employed. It is therefore 

 probable that the mechanism of the inhibition of hemolysis by 

 the citrate is similar in the various other instances by biological 

 hemolysins which have been mentioned. 



From the facts which follow, and for other reasons, we are led to 



* Bordet and Gay, see page 403, have also described similar facts in dealing 

 with the inactivation of alexin by sodium citrate. 



