1 8  Staining  Vegetable  Tissues.  { ^iSJBT^ 
STAINING  VEGETABLE  TISSUES.1 
It  is  found  in  practice  that  sections  prepared  for  microscopical 
examination  become  much  more  intelligible,  even  to  experienced 
workers,  if  they  are  suitably  stained.  By  this  is  meant  a  process 
of  differentiation  of  the  tissue  systems,  based  upon  the  employment 
of  various  dyestuffs.  In  many  instances,  too,  the  recognition  of 
certain  cell-contents  is  rendered  more  certain.  Squire  divides  such 
coloring  agents  into  nuclear,  plasmatic  and  specific  stains.  The 
first-named  are  of  value  in  proportion  as  they  exhibit  a  selective 
affinity  for  the  substance  of  nuclei,  whilst  leaving  the  ground 
substance  comparatively  uncolored.  Such  stains  are,  of  course,  only 
needed  in  dealing  with  fresh  tissues,  and  there  is  little  doubt  that 
haematoxylin  is  the  best  for  the  purpose.  There  are  many  different 
formulas  for  its  preparation,  but  it  is  both  difficult  and  tedious  to 
prepare  satisfactorily  by  most  of  them.  The  formula  for  Ehrlich's 
ammoniated  haematoxylin  is  free  from  these  objections.  Haema- 
toxylin, 2  grammes,  and  ammonium  carbonate,  0-4  gramme,  are  dis- 
solved in  proof  spirit,  40  cc,  and  exposed  to  the  air  in  a  shallow  dish 
for  twenty-four  hours.  The  volume  is  then  made  up  to  40  cc.  with 
proof  spirit,  which  is  warmed,  if  necessary,  to  dissolve  any  separated 
crystals.  Ammonia  alum,  2  grammes,  dissolved  in  distilled  water, 
80  cc,  is  then  added;  together  with  glycerin,  100  cc,  rectified 
spirit,  80  cc,  glacial  acetic  acid,  10  cc.  ("  Methods  and  Formulae," 
p.  24.)  The  solution  is  ready  to  be  diluted  for  use  straightway  and 
does  not  deteriorate  by  keeping.  Sections  when  stained  with  it  are 
of  a  violet  color,  but  this  may  readily  be  changed  to  blue  by  wash- 
ing in  an  aqueous  solution  of  sodium  bicarbonate  grain  in  1  oz.). 
As  soon  as  the  color  is  satisfactory  the  sections  should  be  trans- 
ferred to  70  per  cent,  alcohol ;  for,  if  kept  in  water,  the  color  is  apt 
to  fade.  Over-staining  may  be  remedied  by  the  addition  of  one- 
tenth  to  half  per  cent,  of  strong  hydrochloric  acid  to  the  alcohol  and 
subsequent  washing  with  the  sodium  bicarbonate  solution  already 
mentioned.  Carmine  answers  the  same  purpose  as  haematoxylin, 
and  may  be  used  as  an  alternative,  but  does  not  leave  nuclei  so 
sharply  defined.  A  useful  preparation  of  it  is  Grenadier's  alcoholic 
borax  carmine,  made  by  dissolving  borax,  4  grammes,  in  distilled 
water,  100  cc,  adding  carmine,  3  grammes,  and  heating  gently ; 
1  Pharm.  Journal  and  Transactions,  Novbr:  19,  1892,  p.  401. 
