420 BACTERIOLOGY. 
did not destroy the agglutinating properties of typhoid 
blood); and that in October, 1896, the serum test was 
regularly employed in the New York Board of Health 
Laboratory for the routine examination of the blood- 
serum of suspected cases of typhod fever. Since then 
numerous health departments have followed the example 
set by those of Montreal and New York. 
Use oF Driep Buioop. Directions for Preparing 
Specimens of Blood. The skin covering the tip of the 
finger or the ear is thoroughly cleansed, and is then 
pricked with a needle deeply enough to cause several 
drops of blood to exude. Two fair-sized drops are then 
placed on a glass slide, one near either end, and allowed 
to dry. Paper may also be employed, but it is not as 
good, for the blood soaks more or less into it, and 
later, when it is dissolved, some of the paper-fibre is 
apt to be rubbed off with it. The slide is placed in a 
box for protection. 
Preparation of Specimen of Blood for Examination. 
In preparing the specimens for examination the dried 
blood is brought into solution by adding to it and mix-. 
ing it with about five times the quantity of water ; then 
a minute drop of this decidedly reddish mixture is 
placed on a cover-glass, and to it is added a similar 
drop of an eighteen to twenty-four-hour-old bouillon 
culture of the typhoid bacillus, which, if it has a slight 
pellicle, should be well shaken. The drops, after being 
mixed, should have a faint reddish or pink tinge. The 
cover-glass with the mixture on the surface is inverted 
over a hollow slide (the edges about the concavity 
having been smeared with vaseline, so as to make a 
closed chamber), and the hanging drop then examined 
under the microscope (preferably by gaslight), a high- 
