49 
I'he  circumstance,  brought  out  quite  conclusively  in  Table  24, 
that  no  considerable  change  in  the  red  blood  cells  as  regards  the 
action  of  quinine  occurs  during  blackwater  fever,  is  a  point  of 
considerable  importance,  for  a  moment’s  consideration  will  show  that, 
since  healthy  red  cells  are  not  haemolysed  by  even  the  greatest 
concentrations  of  quinine  which  may  conceivably  be  reached  in  the 
blood  when  quinine  is  taken  in  the  doses  ordinarily  administered  in 
malaria,  namely,  one-third  of  a  gramme  to  one  gramme  (five  to  fifteen 
and  a  half  grains),  therefore,  unless  the  sensibility  of  the  red  cells 
is  enormously  increased  in  blackwater  fever,  no  haemolysis  due  to  the 
action  of  quinine  on  red  cells  contained  in  the  circulating  blood  can 
possibly  take  place.  The  circumstance  that,  in  point  of  fact,  no 
marked  change  does  occur,  is  therefore  conclusive  evidence  against 
the  action  of  quinine  in  blackwater  fever  being  in  any  way  related 
to  a  greater  vulnerability  of  the  red  blood  cells  taken  as  a  whole. 
The  observations  given  in  Table  24  do  not  afford  any  information  as 
to  whether  any  very  small  fraction  of  the  red  blood  cells — such  as 
would,  owing  to  its  relative  insignificance,  fail  to  be  recognised  by 
the  method  employed  may  not  be  unduly  sensitive  to  the  action  of 
quinine.  In  the  next  sub-section,  an  observation  on  the  action  of 
quinine  on  red  blood  cells  containing  malarial  parasites  is  recorded, 
but  the  further  consideration  of  this  problem,  which  depends  for  its 
solution  partly  upon  a  knowledge  of  the  actual  amounts  of  red  blood 
cells  destroyed  during  attacks  of  blackwater  fever,  will  be  more 
conveniently  deferred  for  the  present,  and  dealt  with  again  in 
Section  5  (pp.  136  to  165). 
(c)  The  action  of  quinine  on  red  blood  cells  aifected  luith 
vial  aria  I  parasites. 
In  any  attempt  to  elucidate  the  mechanism  of  blackwater  fever, 
it  is  a  matter  of  the  first  importance  to  ascertain  whether  red  blood 
cells  affected  with  malarial  parasites  are  more  readily  haemolysed  by 
quinine  than  are  healthy  red  cells.  In  order  to  study  this  point,  it  is 
necessary  to  obtain  blood  which  is  relatively  rich  in  intracorpuscular 
parasites.  Nearly  all  the  cases  of  malaria  which  came  under  our 
notice,  however,  had  already  been  treated  with  quinine,  and  parasites 
were  found  in  the  blood  films  examined  in  very  scanty  numbers  or 
D 
