430 



Drs. C. Shearer and H. W. Crowe. 



Treatment. 



Growth, 24 hours. 



No saline — 



(a) Leucocytic deposit planted out immediately 



(4) Leucocytic deposit crushed and planted immediately 



Saline for three hours — 



(al) Leucocytic deposit planted out after three hours stand- 

 ing in '85 per cent. NaCl 



(Jl) Leucocytic deposit crushed and planted out after three 

 hours standing in '85 per cent. KaCl 



Good. 

 Good ; better than (a) . 



Delayed and poor. 

 One colony only. 



At this point it seemed to us that it ought to be possible by making use of 

 the opsonic technique to arrange an experiment which might provide a crucial 

 test of our hypothesis. 



The meningococcus, when first isolated from the spinal canal, is not 

 susceptible of being taken up by the phagocytes in the presence of normal 

 serum. There are said to be exceptions to this rule (Kolle and Wassermann), 

 but so far in our work we have met none. During sub-culture the organism 

 gradually loses the power of antagonising the action of the leucocytes, until 

 after a month or six weeks of growth under laboratory conditions, a very 

 considerable opsonic effect can be demonstrated. Immune serum on the 

 other hand is a most powerful " opsoniser " of freshly isolated cocci. The 

 contrast between an opsonic film prepared with normal serum and that 

 prepared with immune is very striking. 



Since it was our desire to obtain leucocytes filled with meningococci, clearly 

 we were right to employ freshly isolated cultures, and sensitise the emulsion 

 made from stich a culture with the serum of the patient from whom the germ 

 was isolated. As a control we desired to utilise leucocytes with very few 

 germs inside them ; the same emulsion sensitised by a non-immune normal 

 serum gave us what we wished. 



Eemembering the poisonous action of the normal saline when applied to 

 meningococci, we could readily free the leucocytes which we had charged or 

 intentionally left uncharged from any loose germs which might not have 

 been ingested, and in this way our results were not obscured by the growth of 

 the organisms untouched by the phagocytes. We had to be careful, however, 

 not to emulsify the culture used for the purpose of making the opsonic mixture 

 in normal saline, since the toxic action of the saline would have come into 

 play and seriously interfered with the result of the experiment. It would 

 have been very difficult under these circumstances to appraise properly the 

 leucocytic content, as many of the germs would have been killed by the saline 

 beforehand. 



