Am'/a0n.yiS9arm'}  Drug  Sections  for  Microscopical  Examination.  43 
firmly  fixed  to  a  table  by  means  of  another  screw,  the  specimen  is  im- 
bedded in  a  piece  of  carrot,  or  a  mixture  of  lard  and  hard  paraffin  ; 
the  whole  is  put  into  the  well,  and  as  the  screw  is  turned  and  gradually 
pushes  out  the  whole  of  the  contents  of  the  well,  sections  are  made 
with  a  razor  or  a  section  knife,  which  is  nothing  more  than  a  large 
razor  without  a  handle. 
The  knife  and  specimen  should  be  kept  well  wetted  with  dilute 
spirit,  and  the  sections  may  be  kept  until  wanted  in  slightly  diluted 
spirit.  It  is  not  necessary  to  use  rectified  spirit  in  section  preparing, 
but  the  methylated  spirit  must  not  contain  any  kind  of  gum.  A 
rough  and  ready  test  of  the  fitness  of  the  spirit  is  to  pour  it  into 
water ;  it  should  not  affect  the  brilliancy  of  the  water  in  the  slightest 
degree. 
For  very  friable  tissues  a  special  treatment  is  required.  First  soak  the 
drug  in  strong  alcohol,  then  it  ether.  Now  prepare  a  solution  of  cel- 
loidin  in  equal  parts  of  alcohol  and  ether,  about  the  thickness  of  gly- 
cerin (reserve  one-third  of  this  solution).  To  one-third  of  this  solu- 
tion add  its  own  bulk  of  alcohol  and  ether,  in  equal  parts,  and  to  the 
remaining  one-third  add  twice  its  bulk  of  alcohol  and  ether  in  equal 
parts.  Take  the  tissue  out  of  the  ether,  and  put  into  the  thinnest  of 
the  above  three  solutions,  for  a  few  hours,  then  transfer  to  the  thicker 
one  for  three  or  four  hours,  and  lastly  to  the  thickest  for  a  day ;  take 
out  and  dry  in  the  air  and  place  in  spirit  until  quite  hard  and  opaque. 
It  can  now  be  easily  cut. 
The  sections  will  be  much  more  easily  examined  if  they  are  stained 
one  or  more  colors,  and  if  they  are  to  be  stained  they  must  usually  be 
first  bleached.  First  wash  out  the  spirit  by  placing  in  water  and  then 
bleach  by  soaking  in  liq.  sodse  chlorinatse,  B.  P.,  for  from  two  to  ten 
hours.  When  all  the  color  has  disappeared  from  the  sections  wash 
them  in  water  three  or  four  times  at  least.  They  can  now  be  kept  in 
spirit  until  required.  Judson's  dyes  were  at  one  time  used  for  stain- 
ing these  sections ;  but  now  specially  prepared  stains  are  more  gener- 
ally used,  which  can  be  bought,  or  made,  if  more  than  a  very  small 
quantity  is  required.  For  excellent  recipes  for  such  stains  consult 
Bower  and  Vines  "Practical  Botany." 
The  spirit  should  first  be  washed  out  of  the  specimen.  It  should 
then  be  immersed  in  the  staining  fluid  for  from  three  to  ten  minutes, 
and  washed  in  spirit  for  from  ten  to  fifteen  minutes.  Lastly,  the  sec- 
tion, which  now  presents  a  dull  appearance,  is  cleared  by  placing  on 
