676 OPSONISATION FROM A BACTERIAL POINT OF VIEW, ETC., 



been heated contained a substance which lessened opsonisation, 

 the bacteria themselves were more easily opsonised than the 

 ordinary cells from an agar culture, as the following shows — 



Cocci per leucocyte. 



Bacteria distributed in saline 3*8 



Bacteria heated in saline and then washed 6*2 

 An attempt was then made to determine the action of the 

 bacterial extract upon normal bacteria, corpuscles and serum 

 individually. The serum and suspensions were so prepared (whole 

 and half volumes) that the final incubation-tests contained similar 

 dilutions of suspensions and of serum. 



1. Bacterial extract + an equal volume of bacterial suspen- 



sion, incubated for 15 minutes, centrifugalised, washed, 

 suspended in original volume of normal saline 



2. Bacterial extract + an equal volume of corpuscular sus- 



pension, incubated for 15 minutes, centrifugalised, 

 washed, suspended in original volume of normal saline... 



3. Bacterial extract + an equal volume of bacterial suspen- 



sion, no preliminary incubation 



4. Bacterial extract + an equal volume of serum, incubated 



for 15 minutes 



Cocci per 

 leucocyte. 

 Total cells. 



3-6 



4-4 

 3-0 

 1*9 



The action of the bacterial extract upon the serum (No. 4) 

 shows that the depressing action of the substance extracted by 

 the hot normal saline from the bacteria has been exerted upon 

 the serum only, and, since it is the opsonic activity that had been 

 determined, it follows that the extract contains anti-opsonin. 



The temperature of growth. — A preliminary test having shown 

 that the bacteria which had been grown on agar at 22° were 

 more easily opsonised than those grown at 37°, the following 

 tests were made : — 





Cocci per leucocyte. 



Bacteria grown at 37° 



i. 



31 

 55 



ii. 



41 

 53 



iii. 



10 

 17 



iv. 1 v. 



7 14 

 11 20 



vi.* 



12 

 24 



vii. 



4 

 5 



viii* 

 4 5 



Bacteria grown at 22° 



6 







vi*., a three days' culture; viii.*, a four days' culture. 



