654 
Specimens  for  a  Herbarium. 
5  Am.  Jour.  Pharm. 
i      Sept.,  1921. 
will  render  them  impervious  to  attack  by  parasitic  insects  and 
moulds.  It  will  not  be  appropriate  to  offer  a  few  observations  on 
the  mounting  of  the  plants.  The  most  satisfactory  support  is  What- 
man's thick,  white  cartridge  paper,  such  as  is  used  by  artists  for 
sketching.  The  ordinary  gum  of  commerce  frequently  contains  sul- 
phurous acid  added  as  a  preservative,  and  should  therefore  not  be 
employed  as  an  adhesive,  since  it  is  liable  to  bleach  the  plant  colors. 
The  best  mountant  is  a  mucilage  of  the  pure  gum  acacia  of  the  B.  P. 
to  which  has  been  added  a  few  grains  of  Beta-naphthol  to  prevent 
its  decomposition.  This  preparation  has  the  advantage  of  being 
free  from  chemical  impurities,  is  firmly  adhesive,  and  is  invisible. 
It  will  be  shown  later  that  it  is  sometimes  advisable  to  divide  a 
plant  into  its  component  parts  before  preserving,  and  where  this 
has  been  done  the  general  rule  for  mounting  is  to  fix  the  main  axis 
and  foliage  leaves  to  the  paper  support  first,  then  the  inflorescences 
can  be  easily  fitted  in  their  correct  positions.  The  tissues  being  strong 
and  inflexible  after  the  preservation  treatment,  there  is  no  difficulty 
in  reassembling  the  parts.  Dissections  illustrating  the  construc- 
tional characteristics  may  be  mounted  beside  the  complete  plant. 
The  liability  of  these  component  parts  to  fade  and  crinkle  is  avoided 
by  the  new  method,  thus  overcoming  a  time-honored  difficulty. 
Thus,  excellent  illustrations  of  the  primrose  can  be  made  exhibiting 
the  pin-eyed  and  thrum-eyed  varieties  and  their  adaptability  to 
cross-fertilization.  It  was  noticed  that  when  this  ironing  process 
is  employed  the  liability  of  the  dissections  going  green  is  obviated. 
With  large  flowers  and  leaves  the  adhesive  may  be  applied  to  the 
back  of  the  plant  itself,  while  for  small  examples  it  should  be  spread 
on  the  paper  only.  When  the  paste  has  been  applied  and  the  speci- 
men fixed  in  position  it  should  be  firmly  pressed  with  a  soft  'cloth 
to  ensure  the  removal  of  air  bubbles  which  tend  to  form  under  the 
leaves,  and  if  ignored  at  this  stage  will  give  the  plant  a  wrinkled  ap- 
pearance when  it  is  dry.  We  possess  a  collection  preserved  and 
mounted  as  detailed  above  that  has  retained  the  color  of  both  flower 
and  foliage  during  a  period  of  eight  years. 
Certain  orders  of  plants  demand  special  treatment  to  which  our 
process  is  readily  applicable.  A  few  examples  will  be  mentioned 
and  will  serve  to  demonstrate  the  practical  possibilities  of  the 
method. 
