CHAPTER  Vm

BACTERIOLOGIC  METHODS

Bacteriology  has  become  so  important  a  part  of
medicine  that  some  knowledge  of  bacteriologic  methods
is  imperative  for  the  present-day  practitioner.  It  has
been  the  plan  of  this  book  to  describe  the  various  bacteria
and  bacteriologic  methods  with  the  subjects  to  which
they  seemed  to  be  particularly  related.  The  tubercle
bacillus  and  its  detection,  for  example,  are  described  in
the  chapters  upon  Sputum  and  Urine;  blood-cultures
are  discussed  in  the  chapter  upon  Blood.  There  are,
however,  certain  methods,  notably  the  preparation  of
media  and  the  study  of  bacteria  by  cultures,  which  do
not  come  within  the  scope  of  any  previous  section,  and
an  outline  of  these  is  given  in  the  present  chapter.
L  APPARATUS

Much  of  the  apparatus  of  the  clinical  laboratory  is
called  into  use.    Only  the  following  need  special  mention :

I.  Sterilizers. — Two  are  required.
The  dryj  or  hot-air  sterilizer,  is  a  double-walled  oven
similar  to  the  detached  ovens  used  with  gas  and  gasolene
stoves.  It  has  a  hole  in  the  top  for  a  perforated  cork
with  thermometer.
The  steam  sterilizer  is  preferably  of  the  Arnold  type,
opening  either  at  the  top  or  the  side.   An  autoclave,  which

454


APPARATUS  455

sterilizes  with  steam  under  pressure,  is  very  desirable,
but  not  necessary.  An  aluminum  pressure  cooker  is  a
very  satisfactory  substitute  for  the  autoclave.  It  costs
about  fifteen  dollars.
