Aljanuarry  Pi9i8m'  }  diluting  Fluid  for  Counting  Blood  Corpuscles.  29 
DILUTING  FLUID  FOR  COUNTING  BLOOD 
CORPUSCLES.1 
Jacob  Diner,  MD.,  New  York. 
The  need  of  a  good  diluting  fluid  for  the  purpose  of  counting 
blood  corpuscles  has  often  been  impressed  on  me  while  working  in 
the  laboratory  and  in  hospitals.  Those  mentioned  in  textbooks  have 
many  drawbacks.  Some  form  a  precipitate  on  standing;  others 
while  remaining  clear  do  not  permit  of  the  addition  of  staining  solu- 
tions so  that  the  white  corpuscles  may  be  differentiated  from  the 
red  corpuscles  while  making  the  count ;  still  others  destroy  the  red 
corpuscles  if  the  diluted  blood  is  permitted  to  remain  in  the  count- 
ing pipette  for  some  hours. 
With  the  object  in  view  of  securing  a  fluid  which  will  do  away 
with  the  objections  mentioned,  I  have  done  some  work  along  this 
line  and  have  obtained  what  I  believe  to  be  an  ideal  diluting  fluid. 
This  fluid  permits  of  a  simultaneous  counting  of  white  and  red  cor- 
puscles ;  it  keeps  indefinitely  without  precipitating ;  it  retains  the 
normal  shape  of  the  corpuscles,  and  the  diluted  blood  kept  in  the 
diluting  pipette  for  over  a  week  was  as  perfect  as  wrhen  first  drawn. 
The  formula  is  as  follows : 
Sodium  chloride    0.85  gm. 
Sodium  citrate    2.00  gm. 
Azure  II    0.001  gm. 
Formaldehyde  solution,  U.  S.  P   3  drops. 
Distilled  water  enough  to  make   100  c.c. 
The  sodium  salts  are  dissolved  in  the  water,  the  formaldehyde 
solution  is  added,  the  azure  is  added,  and  it  is  shaken  well.  It  may 
be  kept  in  any  kind  of  a  bottle. 
The  technic  of  using  it  is  the  same  as  with  Toison's,  Hayem's  or 
any  other  fluid.  The  findings  are  computed  according  to  the  degree 
of  dilution. 
1  Reprinted  from  The  Journal  of  the  American  Medical  Association. 
