AGf~ICULTURAL RESEARCH, PUSA.

CULTll' ATION OF' MICRO-ORGANISMS Hi')
make sub-inoculations, as scanty organisms may not
be observed, but still develop colo nics in subculture.
If no result is obtained after twenty-four hours'
incubation, the blood-broth should be incubated
continuously for at least foul' days, films and subinoculations
being made each day.
A most convenient instrument for drawing aseptically a
blood sample from a vein is the so-called Behring VClllll/!.l It
also servcs as a container for transmitting the sample to the
laboratory, and provides medical practitioncrs with a simple
means of carrying out thc clinical technique of blood culture.
It consists of an evacuated receiving-tube closcd by a hollow
rubber stopper, and a necdlc attached to a narrow glass
connecting-tube which passes through the stopper and is kept
closed by a simple valve mrangement (see diagrams, p. ]'U.). The
needle is enclosed in a sealed extension of thc connecting-tuhe.
Both the needle and interior of the receiving-tulJc arc sterile.
The needlc is cxposed by breaking off the covering tube and
is inserted into a vein; thc val vc is thcn opcned by bending
thc "knee" fOTIllcd by the receiving and thc connecting
tubes. Blood is automatically drawn into the receiving-tube
and thereaftcr the valve is allowed to close. In addition to
the "venule" for collecting ordinary hlood samples, special
" venules" arc obtainable-c.g. containing broth for blood
culture, bile for blood cultUre in enteric fever, glass beads to
defibrinate the blood, citrate solution to obviate coagulation, etc.
DISPOSAL or CULTURES
Cultures to be discarded should be killed by heat or
antiseptics before the container is cleaned 1'01' re-use.
In the ease of non-sporing organisms, it is sufficient
to remove the cotton-wool plugs, and immerse the
tubes and plugs in a large basin of 3 pCI' cent. lysol
or cresol.
When 1 oz. screw-capped bottles are used as testtubes,
the cap is completely unscrewed, and it and
the bottle placed in the lysol solution.
Cnlill'res of sporing organ'isms, such as B. tetani"
B. anthracis, etc., should be sterilised by (t1ttoclaving.
1 These instruments can be obtained from Bayer Products
Ltd., London.