BY R. GREIG-SMITH. 699 



obtained by any of these methods. The inference is that the 

 opsonins exist already formed in the blood-plasma and are not 

 liberated from the leucocytes upon their destruction during 

 clotting. Briscoe* has either brought forward or emphasised 

 the idea that the opsonins are in some way related to the forma- 

 tion of fibrin, and indeed are largely derived from the original 

 fibrinogen and liberated during clotting. Experiments were 

 made to elucidate this problem. The plasma was rapidly centri- 

 fugalised and while still unclotted was mixed with a suspension 

 of bacteria in 0*8% citrate and to this the corpuscles in 1% saline 

 were added. 





Cocci per leucocyte. 





a 



b 



c 



d 





18 



1-8 



3-0 

 32 



10-4 

 100 



3-8 

 3*8 



Serum citrated 







These show that the formation of clot does not influence the 

 production of opsonin in any way. 



Conclusions regarding the opsonisation, chiefly of M. aureus. — 

 The following is a brief summary of the conclusions which have 

 been arrived at from the research : — 



1. A two-day's culture is more completely opsonised than a 

 younger or an older culture. 



2. The older the culture the greater is the intraphagocytic 

 digestion. 



3. There are no auto-opsonins formed in moderately old 

 cultures. 



4. Races of different ages are opsonised to the same extent. 



5. Bacteria from agar cultures are more easily opsonised than 

 the washed bacteria from bouillon cultures. 



6. The presence of calcium phosphate in bouillon lessens the 

 opsonisibility of the bacteria grown in it, while the presence of 

 sodium chloride increases the action. 



* Brit. Med. Journ. Nov. 16th, 1907, 1423. 



