BY R. GREIG-SMITH. 



675 



It is evident that the cell-free bouillon has a depressing 

 influence which is so pronounced that even in a dilution of yg-, 

 which is ^g- x 1, or T |- F of the whole test, the phagocytic index is 

 reduced from 4-3 to 2-9, and from 7 3 to 4-1 or 4-7. The 

 depressing constituent may be an anti-opsonin, aggressin or anti- 

 phagin. 



The anti-opsonic substance is not influenced by heating at 60° 

 for 15 minutes, indeed, the depressing action is slightly 

 augmented, as the folio wins: shows : — 





Cocci per leucocyte. 





not heated. 



heated. 



Saline (check test) 



Cell-free bouillon 



diluted 16-fold 



32-fold 



46 

 1-7 



2-8 

 3 3 



1-6 

 2-2 



2-7 



By heating bacteria in normal saline at 60°, Bail and Kichuchi 

 were able to extract an anti-bacteriolysin and Weil obtained an 

 anti-agglutinin. Since both of these antibodies were extracted, 

 it might be possible to obtain yet another, an anti-opsonin, by 

 the same process. Accordingly, a 24 hours' agar culture of M. 

 aureus was distributed in about 2 c.c. of normal saline and heated 

 at 60° for an hour. The bacterial cells were eliminated by 

 centrifugalising the suspension. To a portion of this cell-free 

 extract an equal volume of bacterial suspension was added and as 

 a control upon this the same bacterial suspension was added to 

 an equal volume of normal saline. The tests, i. and ii., were made 

 at different times, the extracts being obtained from agar cultures 



of similar age. 



Cocci per leucocyte, 

 i. ii. 



Normal saline 6*2 5*3 



Bacterial extract 4*2 3*4 



It is clear that the saline extracted something of the nature of 

 an anti-opsonin, for while the saline in which the bacteria had 



