831 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
is complicated, but as the separate stages or details are quite simple, 
aud as tlie method is applicable not only to sputum but to any fluid 
containing micro-organisms, it seems probable that it may succeed where 
several other methods having a similar object have failed. Owing to its 
length we can only give the coarser details of the process, and for the 
finer ones must refer to the original, wherein the minutest particulars 
will be found. 
The sputum is mixed with 5 per cent, caustic potash solution until 
it becomes perfectly fluid. The mixture is then shaken in a “milk- 
punch shake,” in order that the bacilli may be evenly distributed 
throughout the fluid. The sputum is then transferred to a burette and 
dropped out on cover-glasses. The flow of sputum from the burette is 
regulated by means of a groove filed on one side of the aperture of the 
stop-cock. By this device the equable flow of a series of equal-sized 
drops was insured. The equal size of drops containing an equal 
number of organisms is, of course, the great desideratum. The best 
size for the drops was found to be 100-150 to the cubic centimetre of 
sputum. 
The next step is to spread the sputum on the cover -glass so as to 
form a thin film. This is done on a turntable, the sputum being spread 
by means of a fine platinum needle, the point of which is bent at an 
angle of about 45°. The cover-glasses, kept in a perfectly horizontal 
position, are to be dried at 35-40°, and then surrounded by a ring of 
paint composed of lampblack and serum. The layer of sputum is next 
to be covered with a thin film of sterilized serum, which is coagulated 
at a temperature of 80°-90° C., and then the caustic potash must be 
extracted from the sputum by means of alcohol, the solvent action of the 
latter being aided by heating in the thermostat. The main object of 
the serum film is to prevent any of the bacilli being removed during 
manipulation. The sputum is then stained with phenol-fuchsin and 
decolorized by alternate immersion in alcohol and weak sulphuric acid. 
After having been washed with water, the preparations are merely dried 
on blotting-paper and then mounted in balsam. 
The next part of the method deals with the actual counting and 
the apparatus necessary thereto. In a No. 12 eye-piece is inserted a 
diaphragm made of black paper in which a small hole has been cut. 
The aperture of the diaphragm is traversed by a hair-line. In order to 
be quite accurate about the fields, the latter are indicated by fixing a 
cork to one of the screws of the mechanical stage. The cork is armed 
with a thin wooden indicator terminating in a needle. The needle is 
made to point to the radial divisions on a cardboard scale placed by the 
side of the Microscope. The scale is affixed to a wooden circle, the 
centre of which is cut out in order to allow the stage-screw to be easily 
manipulated through the aperture. By this simple apparatus the size 
of the drop in fields is measured. The number of fields varies from 
180-220, and the method of calculation is from a given case as follows : — 
A drop 200 field-widths in diameter is found to contain (average of 
500 fields) 5 bacilli to the field ; then 200 2 X 0*7854 = 31,416 (area of 
drop in fields) X 5 = 157,080 bacilli to the drop. 
The bacilli are counted as they pass under the hair-line of the dia- 
phragm, and their number is registered by a machine known as the 
