122 Proceedings of Royal Society of Edinburgh. [sess. 
watched carefully, and any showing signs of contamination are 
at once removed and destroyed. Every second day the contents 
of each flask are shaken to break up the stalactites and prevent 
the formation of growths in masses, which might afterwards 
block the needle of the injection syringe. Once a week every 
flask and table is wiped down with corrosive sublimate solution, 
and the floor scrubbed with the same antiseptic, as a precaution 
against the countless moulds which flourish in the steamy Bombay 
climate. At the end of six weeks the growth of stalactites- 
has completely ceased, and though bacilli remain alive in the 
flasks for months sometimes, yet no perceptible thickening 
of the fluid takes place after the lapse of this period. The 
flasks containing the most turbid fluid are chosen, therefore,, 
and sent into an adjoining room, where they are tested for purity. 
The number of flasks thus sent out daily varies from twenty to- 
thirty, according as the demands for material or other circum- 
stances necessitate. The testing is done by withdrawing a drop 
of fluid from each flask, with the usual precautions, and smearing 
this on the surface of a couple of dry agar tubes. The requisite 
dryness of the agar jelly is got by keeping the tubes in a closed 
jar containing quicklime for a couple of days or so, and the agar 
is ready for use when it has shrunk away a little from the glass at 
the bottom of the tube. If the agar is thus dried, the fluid con- 
taining the bacilli is at once absorbed by it, and two days after, a 
characteristic growth of plague microbes is found covering the 
entire surface. Four days after these tubes are sown they are 
examined by the testing officer, along with the Superintendent, 
and the result noted in the register kept for the purpose. In 
case either of the examiners should have any doubt as to the 
appearance of any of the tubes, a portion of the contents is at 
once placed in a small test flask and the formation of stalactites 
watched for. Only when an unanimous verdict is given by 
both examiners is a flask passed as fit for use. The flasks, 
immediately after testing, are passed on into the sterilising room, 
where they are taken in hand by one of the native medical men. 
They are then firmly fixed on heavily-weighted retort stands, 
and immersed in water kept at 60° C. (140° F.) in a jacketed 
tub. The flasks are arranged in a ring round the circumference of 
