174  Study  of  Urine,  Sputum  and  Blood.  {^mAJp°rnr;i9S)arm- 
pages  80  to  81,  where  a  collection  of  plates  of  this  organism  is 
given. 
Of  all  the  methods  given  for  the  fixing  of  blood  specimens,  none 
other  is  so  satisfactory  as  heat ;  as  it  not  only  fixes  the  specimen  to  the 
cover-glass,  but  favors  its  reaction  to  stains  and  preserves  the  form  of 
the  corpuscle.  Fixing  by  heat  is  best  accomplished  in  the  following 
manner :  A  bar  of  copper  1 5  x  3  x  ^  inches  is  placed  on  a  tripod, 
and  thoroughly  heated  by  a  flame  which  is  placed  under  one  end. 
The  temperature  of  the  bar  is  determined  by  dropping  water  on  its 
surface,  and  the  point  at  which  the  water  boils  is  where  we  place  our 
cover-slips,  specimen  down,  and  allow  them  to  heat  for  twenty  min- 
utes.   Specimens  thus  fixed  can  be  studied  at  any  future  date. 
Staining  is  best  effected  by  the  Ehrlich  tricolor  mixture,  which  is 
prepared  as  follows:  'Saturated  watery  solution  of  orange  G.,  6  c.c. 
Saturated  watery  solution  acid  fuchsin,  4  c.c.  To  these  add,  a  few 
drops  at  a  time,  and  shake  well  between  each  addition — saturated 
watery  solution  of  methyl  green,  6-6  c.c.  Then  add  glycerin,  5  c.c. 
Alcohol  abs.,  10  c.c.  Water,  15  c.c.  Shake  well  for  a  few  minutes 
and  let  stand  for  twenty-four  hours ;  do  not  filter  or  pour  stain  from 
the  bottle,  as  disturbing  the  sediment  is  destructive  to  the  stain.  A 
cover-slip  is  now  placed  in  the  forceps  and  a  few  drops  of  the  above 
mixture  is  placed  on  the  specimen,  by  means  of  a  dropper,  and  al- 
lowed to  stain  for  two  or  three  minutes,  when  it  is  washed  in  water, 
dried  and  mounted.  The  advantage  in  using  this  stain  is,  that  you 
can  rarely  overstain  the  specimen,  and  it  demonstrates  clearly  every 
characteristic  presented  by  the  different  cells  found  in  both  health 
and  disease.  In  studying  the  blood  for  parasites,  very  satisfactory 
results  are  obtained  by  staining  by  1  per  cent,  of  eosin  in  70  per 
cent,  alcohol,  for  one  minute.  Wash  in  water  and  stain  with  Dela- 
field's  haematoxylon,  one  minute ;  or  with  a  solution  of  methyl  blue, 
one-half  minute.    The  specimen  is  then  dried  and  mounted. 
Estimation  of  the  number  of  red  and  white  blood  cells,  haemo- 
globin and  differential  counting  form  sufficient  basis  in  themselves 
ior  a  paper,  and  have,  therefore,  not  been  considered  in  this  article. 
Commercial  Calcium  IvACTOphosphate  has  been  shown  by  T.  S.  Barrie 
(Pharm.  Jour.>  1900,  p.  228)  to  contain  35*8  to  44*8  per  cent,  of  free  lactic  acid ; 
12*3  to  15*1  per  cent,  of  calcium  phosphate,  and  41  *o  to  49*9  per  cent,  of  calcium 
lactate. 
