"^'"May^im^™'}      The  Microscope— Hints  to  Beginners.  255 
THE  MICEOSCOPE:  HINTS  TO  BEGINNERS. 
By  Egbert  Aitken. 
As  the  microscope  is  becoming  more  and  more  an  indispensable  instru- 
ment to  ctiemists  and  druggists,  the  following  hints  on  its  use,  and  a 
description  of  the  various  methods  of  mounting,  may  be  of  service  to  those 
desirous  of  becoming  familiar  with  such  a  fascinating  study  as  that  of 
microscopy. 
One  or  two  remarks  may  be  first  made  with  regard  to  the  choice  of  an 
instrument.  First,  the  stand  or  base  ought  to  be  heavy,  to  prevent  shak- 
ing ;  and,  secondly,  the  field  of  vision  should  be  quite  free  from  color.  If 
the  microscope  be  not  of  first-class  workmanship  it  may  show  a  variety  of 
colors  round  the  edge  of  the  field,  thus  rendering  it  useless  for  scientific 
investigation  ;  but  if  a  microscope  is  purchased  from  a  good  maker  there  is 
little  danger  of  finding  these  defects.  Another  and  very  important  test  is 
its  clearness  of  definition.  This  is  usually  tested  by  some  special  object,, 
and  a  very  good  one  is  a  diatom,  one  of  those  very  minute  vegetable 
organisms  which  require  a  high  power  to  bring  out  the  markings  on  the 
siliceous  envelope. 
Presuming  that  a  satisfactory  instrument  has  been  obtained,  with  direc- 
tions for  working  the  accessory  apparatus,  I  will  now  describe  the  methods 
of  dissecting  and  mounting  the  different  vegetable  tissues.  This  branch 
of  microscopy  is  chosen  for  seyeral  reasons,  one  of  which  is  that  students 
in  botany  take  far  more  interest  in  vegetable  histology  if  sections  are  seen, 
with  the  eye,  than  from  engravings  shown  in  botanical  works;  and  I 
therefore  consider  it  a  subject  of  great  interest  to  those  preparing  for  their 
examinations.  Another  reason  is  that  specimens  for  such  a  study  can  be 
obtained  all  the  year  round  with  very  little  trouble. 
Before  proceeding,  it  will  be  necessary  for  the  worker  to  have  ready 
several  glass  slips  with  ground  edges  (these  are  to  be  preferred  to  the  rough- 
edged  slips,  as  the  latter  are  liable  to  scratch  the  stage  of  the  microscope), 
a  dozen  or  two  thin  glass  circles  about  |  inch  in  diameter,  a  razor,  watch 
glass,  and  several  fine-pointed  needles,  with  handles  made  of  cedar-wood, 
similar  to  those  used  for  camel-hair  pencils.  It  will  be  found  advanta- 
geous to  have  one  or  two  of  the  needles  bent  a  little  at  the  tips ;  this  can 
easily  be  done  by  holding  one  in  the  flame  of  the  spirit-lamp  until  it  is 
red-hot,  and  then  bending  with  a  pair  of  pliers. 
The  worker  having  got  together  the  above  requisites  can  now  proceed 
with  the  dissection  of  vegetable  tissues.  Procure  a  leaf  of  the  ordinary 
laurel,  or  one  of  the  spotted  laurel  (Aucuba  japonica);  with  a  pair  of 
scissors  cut  off  a  portion,  insert  it,  edge  in,  into  a  soda-water  cork,  which 
has  been  previously  slit  with  a  knife  at  one  end ;  then  hold  the  cork  in 
one  hand,  and  with  the  other  take  the  razor,  dip  the  blade  in  water,  and 
shave  off  several  slices  of  cork  and  laurel-leaf  as  thin  as  possible.  A  dozen 
slices  may  be  cut  while  one's  hand  is  in  ;  then  float  them  all  into  a  saucer 
half  filled  with  water,  and  with  a  needle  select  what  seems  the  thinnest 
section  of  leaf,  transfer  this  to  the  centre  of  a  glass  slip,  put  one  or  twO' 
drops  of  water  over  it,  and  then  lower  a  glass  circle  gently  over  this;  thi& 
