190 Prof. Muir and Mr. Martin. On the Combining [Jan. 18, 



I. The Effects of Absorbers of Complement on Normal and 



Immune Opsonins. 



We have tested whether or not the three combinations of receptors + 

 immune-body which we formerly used, absorb the opsonin of the immune 

 serum. 



The two following experiments bring out at a glance the differences in 



the effects of treating a normal and an immune-serum in various ways, each 



serum being afterwards tested on an emulsion of the Staphylococcus aureus 



in the usual way : — 



Opsonic index.* 

 Normal serum of rabbit — 



Fresh and untreated 18*1 



Heated one hour at 55° C 0'6 



Unheated and treated with red corpuscles + immune body ... 0*7 



Unheated and treated \ with serum precipitate I *0 



Unheated and treated with emulsion of Staphylococcus aureus... 0*7 



It is thus seen, in accordance with our previous results, that practically 



all the normal opsonin is removed by these various methods of treating the 



serum. To contrast with this we give the results in the case of an immune 



serum. 



Opsonic index. 

 Anti-staphylococcus serum from rabbit — 



Fresh and unheated . 12*3 



Heated one hour at 55° C 2*9 



Unheated and treated with red corpuscles + immune body 3*1 



Unheated and treated with serum precipitate . 3'5 



Unheated and treated with emulsion of Staphylococcus aureus... 0*7 



It is thus seen thatf treating the serum with the substances which absorb 

 complements has practically the same effect on the serum as heating has ; 

 there being approximately the same amount of immune opsonin left. An 

 emulsion of staphylococcus, however, removes the opsonin almost entirely. 



Other confirmatory examples may be given : — 



Treatment oy Precipitate. 



Opsonic index. 

 Anti-staphylococcus serum — 



Fresh and unheated 18 - 2 



Heated one hour at 55° C 6"9 



Unheated and treated with precipitate 5'8 



* The term " opsonic index " is used in the original sense to indicate the average 

 number of cocci contained in a polymorphonuclear leucocyte. The observations given in 

 each table were of course carried out at the same time. 



t The methods of treating a given serum are the same as those given by us in our 

 previous paper, quoted above. 



