426 



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



Experiment 1. 



Expt.l. — Fresh " Sloan " spinal fluid, rich in meningococci, both within and without 

 the leucocytes, was centrifuged lightly to bring down the leucocytes. 



Treatment. 



Growth, 24 hours. 



(1) Leucocytic deposit was washed in 1 per cent, sterile glucose, 



centrifuged three times and planted out 



(2) Leucocytic deposit was washed in 1 per cent, sterile glucose, 



centrifuged six times and planted out 



(3) Upper portion of original centrifuged spinal fluid was centri- 



fuged hard for 15 minutes and planted out 



Good. 

 Good. 

 Good. Far the best. 



In (1) fresh leucocytic deposit containing many meningococci within the 

 leucocytes, was washed three times in 1 per cent, sterile glucose and centri- 

 fuged and planted out on a plate of chocolate medium. The glucose exerts 

 no harmful action on the cocci, while it diso'rganises and probably kills the 

 leucocytes through its hypertonic action. The washing has removed 

 practically all the free cocci. At the end of 24 hours there was a good 

 growth on the plate. This growth could hardly be accounted for by 

 supposing it to be derived from the few free cocci that may have remained 

 over from the washings. 



To test this further, in (2) the deposit was washed six instead of three times 

 and planted out in a similar fashion. The result was the same as in (1). 

 Here the extra washing had no effect in lessening the amount of the growth, 

 which was as great as in (1). 



In (3) the upper part of the original centrifuged spinal fluid, containing 

 few leucocytes but numbers of free cocci, was centrifuged hard for 

 15 minutes. On planting this out, as was to be expected, growth was 

 immediate and greater than in (1) and (2). 



The conclusion to be drawn from this experiment is open to question, 

 as it cannot be said with any certainty that all the loose germs in (1) and 

 (2) were removed by the repeated glucose washings. 



Moreover, the glucose itself is a stimulant to the growth of the meningo- 

 coccus. The following experiment brings out this point, but at the same 

 time shows that this effect is not very great, and probably is not sufficient 

 to disturb the result of our experiments. 



A fairly thin emulsion of the meningococcus used in Experiment 1 

 (500 millions to the cubic centimetre) was made up in distilled water. 

 Successive dilutions were made by mixing 5 c.mm. of this emulsion with 

 25 c.mm. of 1 per cent, sterile glucose broth, removing 5 c.mm. 'and mixing 

 with a second 25 c.mm. of broth, and so on through eight dilutions. A sterile 



