A SIMPLE METHOD OF DETECTING TUBERCLE BACILLI IN FLUIDS. 323 
be so certain and the process so satisfactory as that here given. 
Some authorities have used very complicated methods: I 
note in Far 7 ning for April 26th a description of a Russian 
method, in which the milk is first coagulated by dilute citric 
acid and the coagulum dissolved by phosphate of soda solution, 
then sulphuric ether and water are added, the mixture is shaken 
for fifteen minutes, the solution is allowed to stand, and after 
the fat is separated the remainder of the liquid is taken and 
dilute acetic acid is added until the first sign of coagulam ap¬ 
pears. It is then transferred to the centrifugal machine giving 
3600 revolutions per minute and the deposit is conveyed to two 
slides and examined with oil immersion. 
However, as a result of a series of studies in which, at the 
suggestion of Dr. Adami, I tried various methods of separating 
the bacilli and gaining them from milk, I have eventually dis¬ 
carded one after another of the solvents of the various constitu¬ 
ents of the milk, and have devised a method which appears to 
be at the same time accurate, rapid and cleanly. The method 
is briefly as follows :— 
Taking milk to which, preferably in order to arrest the 
growth of other bacteria which are apt to hide the tubercle 
bacilli, 5 per cent, of glacial carbolic acid has been added, I 
take 30 C.C., 15 c.c. in two tubes, then centrifugalize it for 15 
minutes (preferably in the hand centrifuge manufactured by 
Bausch & Ivomb, Rochester, N. Y.), the supernating fluid is 
poured off ; the precipitated debris, bacteria, etc., which con¬ 
tains the bacilli, is then treated while in the tube with about 
3 c.c. of 5 per cent, caustic potash solution, is mixed up thor¬ 
oughly by giving a good shake and is left for two or three 
minutes. The tube is then filled up to the 15 c.c. mark with 
distilled water and centrifugalized for about 20 minutes. If now 
the supernating fluid be taken off, the minute quantity of debris 
at the base of the tube can be examined right away, or if 
the material is required in a still purer condition completely 
free from caustic potash, a series of dilutions and centrifugaliza- 
tions with distilled water can be carried on. 
