58 PROPERTIES OF ELEMOLYTIC SERA 



From all these experiments it is shown that before lysis 

 Cd has a weak affinity for E + IB molecules, and that in any 

 given case only a fraction of the amount added enters into 

 combination. This result is of high importance in connexion 

 with the general question as to the action of these substances, 

 since it implies that the action of one substance complement 

 increases the combining affinity of another substance 

 complementoid. 



ON THE SATURATION OF THE R + IB MOLECULES WITH 



COMPLEMENTOIDS, AFTER LYSIS HAS OCCURRED 



Seeing that red corpuscles treated with multiple haemoly tic 

 doses of IB take up multiple doses of C, we may produce 

 lysis by a single dose of C, and then find whether the affinities 

 of the remaining R + IB molecules can be satisfied with Cd. 

 The different stages of such experiments are : (a) The addi- 

 tion of several doses of IB to the corpuscles, time being 

 allowed for combination ; (b) Lysis by a single dose of C ; 

 (c) The addition of Cd in excess ; two hours at 37 C. are 

 allowed for combination ; (d) The addition of about one 

 dose of C ; one hour at 37 C. for combination ; (e) The 

 addition of red corpuscles treated with IB to test for the 

 presence of free C. (In case the hsemolytic value of C should 

 fall during the experiment, the same amount of C as 

 that used in (d) should be added to salt solution and 

 placed in the incubator at the same time for an hour ; its 

 value is then tested by adding red corpuscles treated with 

 IB. ) We can in this way test the saturating power of rabbit's 

 or guinea-pig's Cd with rabbit's or guinea-pig's C four 

 possible combinations. A considerable number of experi- 

 ments of this kind have been carried out, but the general 

 result may be stated that after saturation with Cd not more 

 than a fraction of a dose of the added C has been taken up. 



