The Role of the Phagocyte in Cerebrospinal Meningitis. 431 



Emulsion made up in P5 per cent, saline, however, completely avoids this 

 difficulty, as this strength of saline has little or no deleterious action on the 

 meningococcus and does not interfere with the leucocytes. 



Having thus obtained leucocytes ready charged with germs, and also for 

 control purposes other leucocytes almost free from germs, it only remained 

 to destroy a certain proportion of the former by some means or other. To 

 this end we again employed the method of grinding with sterile powdered 

 glass. Finally, by submitting both crushed and uncrushed cells and also the 

 control leucocytes to the action of normal saline, we were able to determine 

 whether or no the organism within the intact leucocytes were still viable. 

 Those which had been freed by the destruction of the leucocytes should have 

 been killed by the unrestrained action of the normal saline. 



For the sake of greater clarity, it is perhaps as well briefly to tabulate 

 the conditions on which this crucial experiment depends. 



They are as follows : — 



1. An immune serum exerts a powerful action in stimulating the 

 leucocytes to take up the germs. We can,, therefore, fill leucocytes at will 

 with meningococci. 



2. Since freshly isolated meningococci are but slightly susceptible of being 

 attacked by the phagocytes with normal serum, as a control, an opsonic 

 mixture where normal serum is substituted for immune will provide us with 

 leucocytes fairly free of meningococci. 



3. We know from the foregoing experiments that normal" saline will kill 

 all meningococci except those ingested and protected by the leucocytes. 



We can finally destroy by mechanical means some of the leucocytes 

 containing meningococci, and resubmit both these and intact leucocytes to 

 the action of normal saline. If our hypothesis that leucocytes protect, 

 meningococci from death is correct,- then from the intact leucocytes growth 

 will take place. 



Provided also that the normal saline is poisonous to the germ, growth 

 from the control leucocytes (treated with normal saline) will only be slight. 



Experiment 5. 



Opsonic mixtures -f ^ = Coccus S + washed leucocytes and serum S (immune). 



<-P = Coccus S + washed leucocytes and normal serum P. 



Coccus S is a recently isolated coccus from patient S. suffering from 

 cerebro-spinal fever. Serum of this patient and a normal man P. was drawn 

 the day before the experiment. A 24-hour culture of coccus S was 

 emulsified in 1*5 per cent, saline to prevent lysis, and the mixtures put 

 up in equal parts of emulsion, serum and leucocytes, and incubated for 



