Am.  Jour.  Pharm. ) 
Sept.,  1921.  5 
Specimens  for  a  Herbarium. 
653 
THE    IMPROVED  METHOD. 
The  improved  method  about  to  be  described,  while  being  ex- 
ceedingly simple  and  calling  for  ho  elaborate  apparatus,  is  free  from 
almost  all  the  disadvantages  cited  above.  About  one  and  a  half 
hours  will  usually  suffice  to  complete  the  whole  operation ;  the  char- 
acters of  the  flowers,  including  the  delicate  gradations  of  color,  are 
permanently  preserved;  the  actual  manipulation  of  the  process  is 
much  easier  than  is  that  of  the  old  method ;  and  after  a  little  prac- 
tice the  procedure  can  be  relied  upon  to  work  on  all  occasions.  It 
may  be  particularly  noted  here  that  the  different  shades  of  green  ' 
in  the  leaves,  which  are  so  rarely  maintained  in  their  true  contrasts, 
are  satisfactorily  preserved  in  collections  treated  in  this  way. 
The  plant  is  first  placed  between  about  twelve  sheets  of  white 
blotting-paper,  so  that  there  are  six  sheets  above  and  below.    It  is 
then  gently  pressed  with  a  moderately  warm  domestic  flat-iron  of 
about  two  pounds  weight.    The  iron  should  be  kept  constantly  mov- 
ing.   The  temperature  of  the  iron  is,  of  course,  an  important  con- 
sideration.   The  best  gauge  is  experience.    If  the  metal  is  too  hot 
the  coloring  matters  of  the  plant,  particularly  the  chlorophyll,  will  be 
decomposed,  and  the  specimens  thus  rendered  useless.    On  the  other 
hand,  if  the  temperature  is  inadequate  the  permanency  is  impaired 
and  the  plant  becomes  brown;  this  is  possibly  due  to  the  fact  that 
the  contained  enzymes  have  not  been  inactivated.    As  a  rule  the 
growth  of  enzymes  is  rapidly  inhibited  by  exposure  to  a  tempera- 
ture of  70 0  C.    The  heat  applied  should  be  sufficient  to  cause  water 
-rapor  to  rise  through  the  blotting-paper  as  the  moisture  of  the 
plant  is  dried  out.    We  suggest  that  no°  C.  would  not  be  very  far 
wrong.    Floral  collections  thus  treated  are  no  longer  flimsy,  but 
dry  and  rigid,  yet  otherwise  retaining  their  natural  appearance.  The 
liability  of  the  blotting-paper  containing  chemical  impurities  with  - 
disturbing  influences  is  not  great,  but  it  should,  nevertheless,  be  rec- 
ognized as  a  possibility.    All  paper  is  bleached  with  calcium  hypo- 
chlorite, and  if  any  traces  should  remain  in  the  material  used  for 
pressing  plants  the  colors  of  the  tissues  may  be  altered.    If  any 
trouble  is  met  with  in  this  direction  another  brand  of  paper  should 
be  tried. 
Immedaitely  after  preservation  in  this  manner  the  specimens 
should  be  painted  over  with  a  dilute  solution  of  mercuric  chloride  in 
absolute  alcohol,  a  suitable  strength  being  about  0.5  per  cent.  This 
