674 0PS0N1SATI0N FROM A BACTERIAL POINT OF VIEW, ETC. 



From these experiments it is seen that the presence of calcium 

 phosphate in the culture-fluid causes the bacteria to be less easily 

 phagocytosed. Common salt on the other hand increases the 

 production of the substances which react with the opsonin of the 

 serum. The addition of alkali up to a certain point lessens the 

 formation of these substances in the presence of sodium chloride, 

 but increases the formation in its absence. In experiment iv. the 

 greater ingestion with large amounts of alkali is due to the 

 bacteria having been collected in groups of two, three and four 

 cocci. 



The addition of a sugar such as saccharose to neutral bouillon 

 apparently favours the formation of larger quantities of the sub- 

 stance which hinders opsonisation, as will be seen from the 

 experiment on page 694. 



The presence of anti-opsonins in old bouillon cultures. — The low 

 index of the washed cells of a 5 days' bouillon culture as com- 

 pared with a 24 hours' agar culture indicated that they were 

 either deficient in opsonisable substance or that the latter had 

 been annulled by some antibody that had been formed in the 

 bouillon. The low index could not be explained by intracorpus- 

 cular digestion. The phenomenon led to the testing of the action 

 of the cell-free fluid from the 5 days' culture in promoting or 

 hindering phagocytosis. The older method of measuring the 

 suspensions was employed as it prevented the results being 

 rendered less sharp by the presence of an excess of saline. The 

 proportions were 3:3:1:1, the last part or eight being the cell- 

 free bouillon diluted with saline. 





Cocci per leucocyte. 





5 days' 

 culture. 







6 days' 

 culture. 



Saline (check test) 



Cell-free bouillon, neutralised, 3 fold dilution.. 



,< .»' », 16 ,, ,, 



not ,, 3 ,, ,, .. 

 „ ,, „ 16 „ „ .. 



4-3 

 1-4 

 2"2 



2-9 



7-3 

 3-2 



3-5 

 4-1 

 3-6 

 4*7 



