256  The  Microscope — Hints  to  Beginners.  {''^"'Srariss?'^"' 
cell.  Sometimes  it  is  slow  to  commence,  as  the  shock  to  the  leaf,  caused 
by  its  separation  from  the  stem,  seems  to  suspend  the  cell  movement.  By 
gently  warming  it  over  a  lamp,  and  waiting  for  a  few  minutes,  the  circu- 
lation will  soon  be  seen.  Viewed  by  the  microscope,  the  movement  is 
from  left  to  right,  but  as  objects  are  reversed  when  seen  through  the 
instrument  the  movement  is  of  course  the  opjDosite  way. 
Before  proceeding  to  describe  the  different  methods  of  mounting,  it  is 
necessary  to  call  the  attention  of  the  worker  to  one  essential,  and  that  is, 
cleanliness.  Every  slide  and  cover  previous  to  mounting  must  be  thor- 
oughly washed,  and  finally  wiped  dry  with  a  piece  of  chamois  skin  or 
cambric  handkerchief;  no  cloth  ought  to  be  used  that  gives  off  fluff. 
Moreover,  when  working  with  the  instrument,  care  should  be  taken  that 
it  is  done  in  a  room  where  there  is  little  dust,  as  this  latter  interferes  sadly 
with  one's  operations. 
Objects  are  mounted  in  various  ways,  as  transparent  objects  or  opaque. 
The  transparent  can  be  mounted  in  two  ways,  either  dry  or  in  fluid.  I 
will  begin  with  the  transparent  method,  and  give  a  list  of  the  articles 
required:  Canada  balsam,  dammar  solution,  glycerin  jelly,  gold  size, 
spirits  of  wine,  oil  of  cloves,  turpentine,  and  camphor  water.  Dammar 
solution  is  made  by  dissolving  equal  parts  of  gum  dammar  and  mastic  in 
benzol;  a  recipe  for  glycerin  jelly  will  be  found  in  the  "  Pharm.  Jour- 
nal," Third  Series,  vol.  v.  Mr.  Pocklington  reccommends  chloride  of 
barium  as  a  preservative,  but  1  find  carbolic  acid  better.  Unless  the 
student  is  working  largely,  it  is  better  for  him  to  purchase  small  bottles  of 
these  preparations,  as  it  does  not  pay  to  make  them  in  very  small  quanti- 
ties. Canada  balsam  and  dammar  are  the  two  media  most  used  for  dry 
objects ;  they  answer  very  well  for  hard  woods  or  dense  tissues,  as  the 
transparency  of  a  section  is  much  increased,  more  especially  by  the 
dammar. 
To  mount  objects  with  the  above,  make  a  transverse  section  of  some 
root,  say,  sarsaparilla,  using  a  cork  for  embedding  the  root.  Having  pro- 
cured a  section  sufficiently  thin,  soak  it  in  turpentine  for  a  day,  then 
transfer  to  the  centre  of  a  glass  slide,  which  must  be  perfectly  clean,  gently 
warm  the  slide,  and  with  a  glass  rod  drop  a  small  quantity  of  balsam  or 
dammar  over  the  object,  taking  great  care  not  to  have  any  air-bubbles. 
Having  previously  cleaned  the  glass  circle  by  breathing  on  it  and  gently 
rubbing  between  the  thumb  and  forefinger  with  a  cambric  handkerchief,, 
warm  it,  and  let  it  down  gently  on  the  balsam,  as  previously  described  for 
temporary  mountings.  By  this  method  a  slight  wave  is  given  to  the  bal- 
sam, which  helps  to  drive  out  the  air-bubbles.  The  slide  should  then  be 
put  aside  in  a  warm  place  for  a  week  or  two,  until  it  is  thoroughly  har- 
dened, after  which  it  should  be  cleaned  from  the  superfluous  medium  with 
a  penknife,  and,  finally,  with  a  small  rag  soaked  in  turpentine.  It  may 
then  be  covered  with  ornamental  paper,  having  a  hole  punched  through 
the  centre,  or  else  finished  with  a  ring  of  gold  size  run  round  the  circle  to 
preserve  it ;  this  ring  is  easily  put  on  Avith  a  Shadbolt's  turntable,  which 
is  a  circular  plate  (usually  made  of  metal)  spinning  round  on  a  pivot,  the 
slide  being  fixed  with  clips  to  the  table,  and,  while  rotating,  a  camel-hair 
pencil  charged  with  the  cement  is  held  at  one  side  of  the  circle,  and  in  the 
