180 Messrs. 8. G. Shattock and L. 8. Dudgeon. [Dec. 21, 
blood, z.e., of his serum and his cells, as distinguished from the resistance 
brought about by his serum alone, the question with which we are essentially 
concerned is whether a further formation of opsonin occurs in vitro, or 
whether the work done by the cells is done by means of the opsonin which 
was present in the blood when the latter was drawn. 
We endeavoured to determine this by means of the following experi- 
ments :— 
One volume of washed immune cells was thoroughly mixed with one 
volume of immune serum, using larger volumes than usual. The mixture 
was then drawn up into three capillary tubes of the usual calibre, and 
incubated for 20 minutes, 30 minutes, and 1 hour. 
At the end of these intervals, an equal volume of citrated salt suspension 
of lving colon bacilli was added to the contents of each capillary tube, 
mixed, and each tube then incubated for 20 minutes. 
By this means, a full supply of active immune cells was allowed to act in 
immune serum for different periods (without the presence of bacilli); the 
phagocytosis was then tested in each case after the same time-allowance, 
viz., 20 minutes. 
Case.—Colon infection of urinary tract ; treated with anti-serum and vaccine. 
1 vol. of immune washed cells and immune serum, incubated 20 minutes, 
1  ,, citrated salt suspension of colon bacilli. 
50 cells contained 73 bacilli after 20 minutes’ incubation. 
1 vol. of immune washed cells and immune serum, incubated 30 minutes, 
1  ,, citrated suspension of colon bacilli. 
50 cells contained 74 bacilli after 20 minutes’ incubation. 
1 vol. of immune washed cells and immune serum, incubated 1 hour, 
1 ,, citrated suspension of colon bacilli. 
50 cells contained 81 bacilli, after 20 minutes’ incubation. 
Summary and Conclusions from the foregoing Group of Observations. 
It will be evident from the concluding observation that no difference in 
phagocytosis is brought about within 20 minutes, in different samples of the 
same immune serum, mixed with the immune cells from the same patient, 
when bacilli are presented, after periods of incubation of 20 minutes, 
30 minutes, and 1 hour; the numbers of bacilli ingested by 50 cells, 
being :— 
13, (WAS 
This crucial experiment proves that the marked difference in the 
phagocytosis observed when bacilli are added to immune blood, and 
incubated for different periods, must be attributed, not to further opsonifica- 
