DOANE-BUCKLEY METHOD All 
render the color less dense. Ordinarily filling the tube to the 1 c.c. 
mark will be sufficient, and this quantity gives an easy factor for cal- 
culating the final results. 
In putting this liquid containing the leucocytes into the blood 
counter considerable care is necessary, owing to the tendency of the 
leucocytes to sink to the bottom. At this place a capillary tube is used, 
and the cover glass was held in one hand ready to cover the chamber as 
soon as the drop was transferred to the counting counter. After 
placing the glass cover over the chamber, about a minute is allowed 
the leucocytes to settle to the bottom of the chamber. There are very 
few foreign bodies likely to be mistaken in counting for leucocytes. 
Ordinarily the polynuclear leucocytes predominate and the stained 
nuclei with the unstained surrounding cell show up very distinctly. A 
few small leucocytes with large nuclei may be found and these may be 
confounded with yeast cells until the worker becomes familiar with the 
distinction. 
As regards counting we have taken a standard with a cubic centi- 
meter as a basis quantity of milk, though we are, of course, aware that 
the corpuscles in the blood are enumerated with a cubic millimeter basis. 
We adopted the centimeter largely for two reasons. In counting bac- 
teria in the milk the cubic centimeter is always the basis employed. 
Simply because the leucocytes were derived from the blood seemed 
to be no reason why the same basis for counting should be employed as 
was used with the blood, while to the ordinary bacteriological worker to 
whom this work will fall, if ever adopted to any extent, the cubic cen- 
timeter standard would be a little more easily comprehended because 
more frequently used. The blood counter holds 75 c. mm. and 1/10,000 
c.c. If 10c.c. of milk are used and the 1 c.c. of fluid is in the tube after 
siphoning, and the coloring matter and the water used to dilute has been 
added, then the resulting number of leucocytes in the counting multi- 
plied by 1000 will be the total number of leucocytes per cubic centi- 
meter in the milk. If a total of 75 leucocytes was counted in the 
chamber there would be 75,000 leucocytes per cubic centimeter in the 
milk, 
In the actual counting under the microscope a square millimeter 
of the counting chamber will be found to be ruled off into 400 smaller 
equal squares. This facilitates an accurate and rapid count. Where 
the number of leucocytes is not great the entire field can be counted 
in a short time. Where there is a great number of leucocytes a few 
squares or sets of squares in different parts of the ruled surface will give 
approximately the number. 
