10 



Prof. R. Muir and Mr. C. H. Browning. [May 17, 



O 



+ C Result = lysis. 



The vertical dotted line indicates a period of incubation for 1 Iwur, 

 unless when otherwise stated. 



After lysis has occurred, however, Cd can combine with the R + IB 

 molecules. It has been shown that a large amount of C can be taken 

 up through the medium of multiple doses of IB, and that the combina- 

 tion of C is a firm one. Thus : 



2 hrs. 



{iV 4C 



+ 



R 

 IB 



Result = no lysis in added 

 corpuscles. 



If, however, we add in the same case 3Cd after lysis by 1C, but 

 before the addition of the other 3C, the result is different, thus : 



2 hrs. 



+ C 



Lysi 



+ 3Cd 



+ 30 



+ o 



IB 



Result = lysis in- 

 added corpuscles. 



In other words, the Cd molecules have united with the R + IB- 

 molecules after lysis, and have prevented the added C from being. 

 taken up ; this is shown by the test corpuscles undergoing lysis by 

 means of the free C. 



To avoid repetition, we may here state that the stages of all such 

 experiments are the following : 



1. To each of a series of tubes containing the standard amount of corpuscles, a 

 certain amount of IB is added, usually three to four hsemolytic doses. 



2. To each tube is added a little more than the hsomolytic dose of complement,. 

 nnd a certain amount of complementoid (heated serum). The tubes are placed in 

 the incubator for an hour at 37 C. Haemolysis, of course, occurs, and time is- 

 allowed for the Cd to combine with the 'R + IB molecules. 



3. To the several tubes in series complement is then added in increasing amount.. 

 Experience sbows how much C is likely to be taken up, and the last tubes should, 

 of course, contain more than this. The tubes are incubated at 37 C. for 2 hours. 



4. To each tube is added the standard amount of red corpuscles, treated 

 previously with 3D of IB, and the tubes are placed in the incubator for another- 

 hour. Haemolysis will, of course, take place in the added corpuscles according to 

 the amount of uncombined C present in each tube. The tubes are then placed in; 

 a cool chamber till next morning ; the red fluid in each tube is pipetted off, and the 

 amount of sedimented corpuscles left is estimated as above described. 



In a control set of tubes complement only is added, and we thus ascertain how 

 much C is taken up when no Cd is present. It is then seen how much C has been, 







