The Role of the Phagocyte in Cerebrospinal Meningitis. 427 



carnel's-hair brush was dipped in the highest dilution, and drawn across 

 the surface of the plate. The remaining seven dilutions were treated in a 

 similar manner. In the end there were eight parallel lines, taking up 

 one half of the plate, each representing a dilution of the meningococcus 

 in glucose. The other portion of the plate was treated in a similar manner 

 with eight successive dilutions of the same quantity of emulsion, in distilled 

 water. The plate was then incubated at 37° C. for 48 hours. A photograph 

 of the plate is shown in fig. 3, after 24 hours' growth. The action of the 

 glucose in accelerating growth will be seen from an examination of the 

 successive lines on the one, as compared with the other half of the plate. 

 A close comparison of the two top lines with the two bottom lines of growth 

 brings out the action of the glucose. In this instance it is slight and 

 inconsiderable. The action of the glucose, therefore, may be safely neglected 

 as a source of grave error. 



There is a further point to be considered with regard to this' and all the 

 following experiments. Are we certain that the leucocytes we are using in 

 these experiments are alive and not dead ? 



We endeavoured to settle this point by two tests. 



Firstly. By an examination of fresh leucocytic deposit of spinal fluid on 

 the warm stage. This elucidated the fact that if the spinal fluid was freshly 

 drawn by lumbar puncture from a cerebro-spinal fever case and was only 

 cloudy and turbid in appearance, and not at all purulent, then practically 

 all the leucocytes were alive, as they always showed vigorous amoeboid 

 movement when placed on the warm stage. If the fluid was purulent, then 

 most of the leucocytes were dead. 



Secondly. It has been shown by Eous and Jones* that a dilute solution 

 of trypan blue in Kinger's solution readily stains the nuclei of dead leuco- 

 cytes, while it will not touch those of the living cells. We have confirmed 

 this point for human leucocytes found in the spinal fluid of cerebro-spinal 

 fever cases. To this end, freshly drawn fluid containing leucocytes was 

 taken which showed obvious amoeboid movement on the warm stage. This 

 was divided into two portions. The leucocytes of one portion were stained 

 for a few minutes in dilute trypan blue in Kinger's solution, and then 

 examined under the microscope; none of them took the stain. To the 

 second portion a little alcohol was added to kill them, and they were then 

 stained as before ; all immediately took up the stain. 



We then applied the trypan blue method of staining to a number of leuco- 

 cytic deposits obtained from cerebro-spinal fever cases, such as those used in 



* Eous and Jones, ' Journ. Exp. Med.,' vol. 23 (1916). 



