it  IS  not  used  up  to  any  considerable  extent  in  the  process,  and  that 
its  concentration  is  therefore  little  altered  by  the  reaction  taking 
place.  To  test  this  point  the  series  of  estimations  recorded  in  Tables 
20  and  21  were  made.  In  these  estimations  a  weighed  quantity  of 
quinine  sulphate  was  dissolved  in  such  an  amount  of  O'Q  per  cent, 
sodium  chloride  solution  as  to  produce  about  the  same  concentration 
as  that  employed  in  the  experiments  given  in  Table"  i.  Red  cells 
were  then  added.  In  the  first  four  experiments  the  weight  of  red 
blood  cells  taken  was  comparable  to  that  in  Table  i,  in  the  remaining 
experiments  much  larger  amounts  of  red  cells  were  employed.  When 
it  was  judged  that  sufficient  time  had  elapsed  for  the  red  cells  to  take 
up  quinine,  the  amount  of  the  latter  still  remaining  in  solution  was 
determined. 
Mel  hod.  Ill  these  estimations  healthy  human  blood  was 
employed  throughout,  being  withdrawn  by  means  of  a  sterilised  glass 
injection  syringe,  from  the  cephalic,  median-cephalic  or  ulnar  vein  of 
the  upper  limb,  which  was  bandaged  close  to  the  axilla  so  as  to 
obstruct  the  venous  circulation.  The  time  occupied  in  withdrawing 
blood  was  from  ten  to  thirty  seconds,  and  the  amount  withdrawn 
ranged  from  4  c.cm.  to  27  c.cm.  Without  any  delay  the  blood  so 
obtained  was  discharged  into  a  beaker  containing  a  freshly  prepared 
I  per  cent,  solution  of  potassium  oxalate,  in  the  proportion  of  five 
parts  of  the  former  to  one  part  of  the  latter,  and  the  mixture  at  once 
centrifugalised.  The  red  cells  quickly  subsided  and  the  supernatant 
serum  was  pipetted  off.  The  red  cells  were  then  added  in  measured 
amounts  to  a  solution  of  quinine  sulphate,  the  bulk  of  which  was 
about  200  c.cm.  The  emulsion  was  kept  in  a  stoppered  glass  bottle 
which  was  shaken  every  half  hour  for  two  hours,  after  which  the 
red  cells  were  allowed  to  subside  at  room  temperature  (17°  C.  to 
19°  C.),  subsidence  being  completed  in  sixteen  to  twenty-four  hours. 
No  haemolysis  took  place.  As  much  ns  possible  of  the  supernatant 
liquid,  which  was  clear  or,  with  the  larger  amounts  of  red  cells,  very 
faintly  opalescent,  was  removed  with  the  aid  of  a  capillary  siphon, 
and  the  amount  of  fluid  still  remaining,  usually  not  exceeding  5  per 
cent,  of  the  original  amount,  was  measured.  It  will  be  noted  that 
the  quinine  solution  after  the  first  two  hours  was  not  everywhere 
equally  exposed  to  the  further  action  of  the  red  cells,  these  gradually 
