566  Opsonic  Theory  and  Tuberculosis.      { AD^mbkl  1907?* 
putting  the  mill  to  the  test  says  that  he  found  it  wanting,  and 
not  one  whit  better  than  the  more  primitive  mortar  and  pestle,  to 
which  he  has  reverted. 
STAINING  THE  SMEAR. 
It  is  unnecessary  to  fix  the  smear  as  is  the  custom  with  some,  by 
means  of  alcohol  or  other  fixative,  as  the  heat  to  which  the  slide  is 
exposed  during  the  process  of  the  preliminary  staining  by  carbol 
fuchsin  is  sufficient  for  the  purpose.    Our  method  is  as  follows  : 
Carbol  fuchsin  with  heat,  2  minutes. 
Wash  with  water. 
Decolorize  with  25  per  cent,  sulphuric  acid. 
Counterstain  with  borated  methyleneblue  30  seconds. 
The  advantage  of  this  latter  counterstain  over  the  much  used  and 
popular  Loeffler's  preparation  is  that  the  protoplasm  of  the  cells  is 
stained,  which  is  not  the  case  with  either  Loeffler's  or  Gabbet's — the 
latter  a  mixture  which  is  both  a  decolorizer  and  stain.  With  the 
protoplasmic  limits  undefined  one  can  readily  comprehend  how 
errors  in  computation  could  be  made  as  it  would  be  impossible,  and 
is  impossible,  to  definitely  locate  an  organism  in  many  instances,  in 
other  words  to  say  whether  it  is  within  the  cell  or  just  without. 
Dr.  Hitchens  has  explained  to  you  what  constitutes  a  bacterial 
vaccine,  and  how  they  bring  about  curative  results.  In  tuberculosis 
we  make  use  of  a  vaccine,  if  one  may  so  term  it,  called  tuberculin, 
and  inasmuch  as  you  may  at  some  time  or  another  be  required  to 
know  of  this  remedy  I  will  briefly  refer  to  it.  There  are  several 
kinds  of  tuberculin  on  the  market  to-day,  but  when  we  refer  to 
tuberculin  we  usually  mean  one  of  the  three  kinds,  either  the  so- 
called  old  tuberculin,  that  known  as  "  TR,"  or  the  Bacillen  emulsion. 
All  of  these  were  originally  the  product  of  Koch's  laboratory,  but 
now  many  laboratories  manufacture  these  for  their  own  use  after  the 
Koch  formula.  The  difference  between  them  is  that  the  former  is 
merely  a  filtered  bouillon  culture  of  the  bacillus  concentrated  by 
heat  to  one-tenth  of  its  volume  while  the  two  latter  contain  the 
actual  bacterial  substance.  At  the  present  time  these  three  kinds 
are  being  very  extensively  used. 
THE  VALUE  OF  ESTIMATING  THE  OPSONIC  INDEX. 
The  earlier  observations  of  Wright  and  Douglas  were  made  with 
organisms  other  than  the  B.  tuberculosis,  and  they  showed,  as  you 
