Am.  Jour.  Pharm. 
Sept.,  1890. 
Microscopic  Notes. 
439 
time  in  the  future.  The  writer  was  led  to  this  paragraph  by- 
several  slides,  made  about  a  year  ago,  of  which  he  cannot  form  the 
faintest  idea  of  how  he  made  them  (previous  treatment  of  substance, 
stain,  medium,  etc.),  and  some  of  these  he  should  very  much  like 
to  duplicate. 
"  Festina  lente" — Make  haste  slowly  !  Hurry  seldom  gives  good 
results ;  take  your  time  in  the  previous  treatment,  staining, 
mounting,  etc. 
Stains. — These  serve  a  two-fold  purpose  :  First,  to  make  more 
easily  visible  extremely  thin,  colorless  and  transparent  elements 
(tissues),  either  directly  by  staining  them,  or  indirectly  by  staining 
the  surrounding  medium.  Secondly,  to  differentiate  the  component 
elements  of  the  object,  so  as  to  render  them  more  readily  recogniz- 
able. This  is  done  with  single  stains  by  the  different  selective 
power  which  the  various  elements  possess,  some  of  the  latter  either 
not  taking  the  stain  at  all,  or  with  varying  intensity,  or  with  different 
colors.  Double  stains  act,  of  course,  by  selection.  For  cursory 
examination  the  most  generally  useful  single  stains  are  :  Methyl 
violet  (purple  ink),  haematoxylin  and  sulphindigotate  of  sodium 
(Arnold's  writing  fluid  does  as  well)  ;  all  of  which  give  better  results 
if  used  much  diluted,  using  longer  time.  Carmine  gives  excellent 
stains,  where  suitable,  but  is  somewhat  troublesome  to  use  properly. 
Microscope  stands, — These  may  conveniently  be  divided  into  two 
great  classes  :  Those  with  facilities  for  applying  substage  apparatus, 
and  those  without  such  facilities.  The  latter  class  is  the  cheapest  (as 
low  as  $15  with  sliding  tube),  and  will  do  for  the  first  year  or  two, 
but  since  it  is  impossible  to  use  a  polarizing  apparatus  with  them 
(and  pharmacists  have  quite  often  use  for  it),  not  to  mention  sundry 
other  pieces  of  apparatus,  the  student  will  sooner  or  later  be  forced 
to  either  sell  his  instrument  or  to  exchange  for  a  stand  of  the  first 
class,  either  of  which  means  loss  of  money.  It  is,  therefore,  better 
from  the  start  to  get  one  of  the  first  class.  This  class  may  be  sub- 
divided into  those  where  the  substage  apparatus  is  fastened  to  a 
fixed  ring  under  the  stage,  and  those  where  the  ring  is  movable  on 
the  mirror-bar.  The  latter  stands  are  certainly  the  handiest,  but 
cost  more  (from  $30  up);  the  first  ones  (with  fixed  ring)  serve  all 
the  purposes  of  even  exacting  pharmacists,  and  are  much  cheaper 
as  low  as  $18,  with  sliding  tube).  Whatever  stand  is  chosen,  it  is 
indispensable  that  the  draw-tube  be  provided  with  society  screw. 
