AmMlZ\Ps^rm }        The  Microscope  in  Pharmacy.  1 17 
are  studied  or  examined  by  the  pharmacist  are  besfseen  with  a  moderate 
power.  It  must  be  remembered  that  when  a  great  magnifying  power 
is  applied  to  the  ordinary  objects  of  the  store  we  are  able  to  see  only 
a  very  small  portion  of  them,  and  the  results  are  unsatisfactory  ;  most 
interesting  objects  that  are  likely  to  present  themselves  can  be  seen  by 
means  of  a  power  under  two  hundred  diameters. 
Three  things  will  be  found  necessary,  viz.:  magnifying  power,  good 
light  and  a  good  instrument.  Almost  all  opaque  objects  can  he  seen 
with  a  power  of  twenty-five  diameters — the  list  includes  seeds,  min- 
erals, preparation  of  plants  and  their  general  structure,  as  shown  by 
sections,  leaves,  roots,  the  crystals  of  Epsom  and  other  salts,  salicin, 
santonin,  quinia,  the  other  alkaloids  of  cinchona,  and  many  other 
objects. 
The  active  process  of  crystallization  and  the  deposition  of  metallic 
silver  in  crystalline  form  from  the  nitrate  in  solution  may  be  shown  by 
placing  a  drop  of  the  solution  on  a  glass  slide,  and  in  it  a  small  piece 
of  brass  wire  ;  immediately  crystals  will  appear  and  grow  till  they 
have  spread  as  far  as  the  liquid  extends.  Similar  results  will  be  obtained 
with  any  concentrated  solution  made  from  the  crystalline  salts  we  have 
on  our  shelves  if  allowed  to  evaporate  spontaneously. 
Many  substances  of  vegetable  origin  are  not  fit  for  medicinal  use  when 
first  gathered  ;  others,  which  are  reliable  when  gathered  and  properly 
and  carefully  prepared,  are  subject  to  deterioration  if  kept  for  some 
time.  Even  the  roots  of  the  virulent  aconite  are  sometimes  converted 
into  impalpable  dust  by  microscopical  insects  ;  the  leaves  of  Conium 
maculatum  and  other  powerful  narcotics  are  rendered  inert  by  the  pro- 
cess set  up  in  their  interior  by  fungi.  These  injurious  changes  are 
often  not  discovered  by  the  naked  eye,  and  explain  the  fact  that  some 
of  the  carefully  prepared  tinctures  and  extracts  are  devoid  of  their 
medicinal  power. 
Prof.  Baily,  of  West  Point,  called  attention  to  crystals  found  in 
plants,  and  that  saline  substances  are  spontaneously  crystallized  within 
the  cells,  existing  in  infinite  numbers  throughout  barks,  woods  and 
leaves  of  numerous  trees  and  shrubs.  The  beautiful  tinted  juices  to 
which  flowers  and  leaves  owe  their  variety  of  colors,  the  sweet  odors 
with  which  they  perfume  the  air,  the  gums,  balsams,  starches,  natural 
alkaloids  in  endless  profusion,  are  fabricated  by  the  vegetable  cell ;  even 
the  lichen  and  smallest  moss  is  an  interesting  object.  Examination 
