302 Prof. R Muir and Mr. C. H. Browning. [Nov. 10, 



IB Rabbit v. Guinea-pig. Guinea-pig's C. 



Experiment XLIL 2 D of IB took up 0'08 c.c. guinea-pig's C. 



8 0-288 



Dose of guinea-pig's C = about 0'3 c.c. 



XLIII. 1 D of IB took up 0-026 c.c. guinea-pig's C. 

 5 0-114 



10 0-254 



Dose of C = 0-25 c.c. 



XLIV. 1 D of IB took up 0-014 c.c. guinea-pig's C. 

 14 0-38 



Dose of C = 0-35 c.c. 



LXIX. 1 D of IB took up 0-04 c.c. guinea-pig's C. 



5 0-28 



10 0-48 



Dose of C = 0-4 c.c. 



From these results it is manifest that the large amount of guinea- 

 pig's complement necessary to produce lysis, combines completely with 

 the guinea-pig's corpuscles treated with the corresponding immune- 

 body, there being, up to a certain point, no complement left over to 

 act on the test corpuscles, and the large dose of immune-body 

 necessary is simply due to this amount being required to bring the 

 necessary complement into combination with the corpuscles. The 

 guinea-pig's complement has, therefore, a weak toxic action on guinea- 

 pig's corpuscles, about ten times weaker than it has, for example, on 

 ox's corpuscles. 



Note. The amount of complement taken up is calculated from the point at 

 which free complement is obtainable after time has been allowed for combination. 

 It will be noticed that the amount of complement taken up is approximately, 

 though not strictly, proportional to the amount of immune-body present. The 

 divergence is more marked when higher multiples are used, as has been noted by 

 one of us in the case of another combination; in other words, what is known as 

 "Ehrlich's phenomenon," is seen to a slight extent. As, however, there is very 

 little evidence of dissociation of complement after it has combined, the phenomenon 

 in this case is probably due to presence of complementoid. 



(b) With RabUfs Complement 



It will be seen from the tables that (a) the M.H.D. of immune-body 

 in this case is small about a tenth of that necessary when guinea- 

 pig's complement is used, and (b) that the dose of complement also 

 is comparatively small, in fact, practically the same as that necessary 

 for the haemolysis of ox's corpuscles. In investigating the amount of 

 rabbit's complement taken up by means of multiple doses of immune- 

 body, interesting and at first very puzzling results emerged. An 



