112  Microscopic  Study  of  Urine.  {An!irireh.SSlJm* 
METHOD  FOR  STUDY. 
(1)  Invert  the  bottle  two  or  three  times  to  insure  that  the  sedi- 
ment is  perfectly  disseminated  through  the  urine,  when  a  small 
quantity  of  urine  is  placed  in  a  special  tube  and  centrifugated  for 
from  2  to  5  minutes.  The  machine  is  not  absolutely  necessary,  and 
for  practical  work  the  urine  can  be  allowed  to  stand  in  a  cool  place 
for  6  to  12  hours,  when  ample  sediment  will  have  collected  at  the 
bottom  of  the  bottle. 
In  case  the  sediment  is  to  be  mounted  as  a  permanent  specimen, 
decant  clear  supernatant  urine,  and  add  an  equal  quantity  of  water 
in  its  stead  and  again  sediment,  repeating  the  process  until  this 
sediment  is  thoroughly  washed. 
(2)  Sediment,  however  obtained,  is  lifted  by  means  of  a  wide- 
mouthed  pipette,  and  a  small  drop  of  it  placed  on  the  centre  of  a 
slide.  The  specimen  is  now  viewed  through  a  lens  to  determine 
its  value ;  and  should  the  subject  be  one  worthy  of  preservation,  the 
above  method  of  washing  having  been  employed,  the  specimen  is 
allowed  to  dry  in  the  air,  after  which  it  may  be  mounted  in  Canada 
balsam.  This  method  will  be  found  of  service  for  inorganic  sedi- 
ments, pus,  blood,  bacteria,  fungi,  and  the  ova  of  animal  parasites. 
Casts  and  animal  parasites,  however,  while  collected  in  the  same 
manner, must  be  mounted  while  yet  moist  (since  drying  causes  dis- 
integration) in  a  special  medium  composed  of  the  following  :  Liquor 
acidi  arseniosi  (U.S.P.)  I  fluid  ounce ;  salicylic  acid,  y2  grain ;  glyce- 
rin, 2  fluid  ounces.  Warm  slightly  until  solution  is  effected,  when 
add  acacia  (whole  tears)  and  again  warm  until  solution  is  saturated. 
After  subsidence  decant  clear  supernatant  liquid.  The  drop  of 
mounting  medium  should  always  be  of  good  size,  since  it  requires  a 
quantity  for  urinary  sediments  of  twice  that  usually  employed  for 
sections.  A  perfect  distribution  of  the  sediment  throughout  the 
medium  is  accomplished  by  drawing  a  needle  from  the  margin  to 
the  centre  of  the  drop. 
STAINING. 
Place  a  small  drop  of  the  sediment  on  a  slide  and  spread  it  over  a 
large  surface  in  order  that  the  cells  be  separated  ;  heat  over  a  flame 
for  three  minutes,  carrying  the  slide  to  the  ulnar  surface  of  the  hand 
every  few  seconds.  A  guide,  in  fixing  by  heat,  is  never  to  raise  the 
temperature  above  that  which  can  be  borne  by  the  surface  of  the 
