Amlpdij9Pooarm'}     Study  of  Urine,  Sputum  and  Blood.  173 
clean  forceps,  as  are  to  be  used ;  arrange  them  on  the  filter  paper 
in  such  a  manner  that  they  can  be  lifted  out  readily  with  the  for- 
ceps. The  cover  is  now  placed  on  the  dish  and  it  is  heated  moder- 
ately. Blood  spreads  much  more  readily  where  the  cover-glasses 
are  warm. 
The  lobe  of  the  ear  is  washed  with  alcohol  or  ether,  and  after 
drying  a  slight  puncture  is  made.  The  first  drop  of  blood  is 
wiped  away  with  sterile  gauze ;  the  summit  of  the  second  drop 
is  touched  by  the  centre  of  a  cover-glass,  which  is  so  held  between 
the  thumb  and  finger  as  not  to  touch  its  plane  surface.  This 
cover  is  allowed  to  fall  gently  on  another  in  such  a  manner  that 
its  margin'  protrudes  at  some  point,  when  the  blood  will  be  seen 
to  spread  between  the  adjacent  surfaces  of  the  covers  ;  the  pro- 
jecting edges  of  the  covers  are  grasped,  and  they  are  separated 
by  pulling  on  the  horizontal,  when  they  are  returned  to  the  Petri 
dish,  specimen  surface  up.  The  ear  should  be  dried  with  the 
gauze  after  each  specimen  is  taken.  Where  it  is  desired  to  study 
the  blood  in  its  fresh  state  for  the  malarial  plasmodium  or  other 
parasites,  the  drop  of  blood  is  taken  as  above  and  the  cover  is 
allowed  to  spread  on  a  slide.  If  it  is  desired  that  the  parasite 
be  kept  living  for  some  time,  a  ring  of  oil  two-thirds  the  diame- 
ter of  the  cover-glass  is  made  on  the  centre  of  the  slide,  and  this 
ring  must  be  broken  at  one  or  more  places.  The  cover-glass  is 
so  placed  on  this  ring  as  to  bring  the  drop  of  blood  in  its  centre, 
when  it  will  be  seen  that  the  spreading  of  the  blood  will  force  the 
oil  to  the  margin  of  the  cover,  all  air  having  escaped  through  the 
opening  in  the  ring  which  is  now  sealed.  Blood  thus  prepared 
shows  no  tendency  to  clot,  and  its  corpuscles  are  well  preserved; 
if  kept  in  a  warm  place  parasites  live  for  an  indefinite  time,  the 
writer  having  kept  the  filaria  sanguinis  hominis  living  for  ten 
days  after  this  method.  When  studying  the  blood  in  its  fresh  state 
for  malaria  the  first  method  is  quite  satisfactory,  if  the  blood  be 
collected  during  or  near  the  time  of  a  paroxysm  (chill).  Under  a 
1- 1 2  oil  immersion,  the  malarial  parasite  appears  as  a  small  hyalin 
body  usually  situated  in  the  blood  corpuscle  and  containing  one 
or  more  granules  of  pigment,  which  are  seen  to  be  in  constant 
vibration  (Browning  movement).  This  organism  may  be  circular,, 
pear-shaped  or  crescentric  ;  and,  in  fact,  there  are  so  many  varie- 
ties, that  the  reader  is  referred  to  "Anders'  Practice  of  Medicine,"' 
