48 
accuracy  of  the  method  employed  no  decided  change  in  the 
susceptibility  of  the  red  cells  to  the  action  of  quinine  is  recognisable. 
The  same  conclusion  also  holds  if  the  conditions  present  are 
examined  individually.  During  the  period  of  haemoglobinuria  eight 
cases  were  examined  (i,  6,  7,  8,  ii,  12,  13,  17);  in  five 
of  these  haemolysis  was  complete  in  three  hours,  the  concentration  of 
quinine  bihydrochloride  being  0'045  per  cent;  in  two  (7,  12) 
haemolysis  proceeded  somewhat  more  slowly ;  and  in  one  (6)  the 
number  of  observations  was  small,  but  the  rate  of  haemolysis  was 
probably  the  same  as  that  of  the  first  five.  Of  the  nine  cases  of 
blackwater  fever  examined  when  haemoglobinuria  had  ceased  (2,  3,  4, 
5,  9,  10,  14,  15,  18)  six  followed  the  normal  comrse,  in  two  (3,  4) 
haemolysis  proceeded  somewhat  more  slowly  than  usual,  and  the 
remaining  one  appeared  to  have  followed  the  usual  course,  though  the 
number  of  observations  is  incomplete. 
Two  observations  were  made  during  a  malarial  attack  (19,  20), 
one  during  the  apyrexial  interval  and  one  during  the  attack,  when 
the  patient’s  temperature  was  103°  F.  In  both  of  these  the 
haemolysis  proceeded  at  a  slightly  slower  rate  than  usual,  being 
completed  in  three  hours  with  a  concentration  of  quinine  bihydro¬ 
chloride  of  0'0535  per  cent,  instead  of  the  more  usual  concentration 
of  0‘045  per  cent.  It  cannot,  however,  be  inferred  from  these  two 
observations  that  a  slight  diminution  in  the  rate  of  haemolysis  is  a 
constant  occurrence,  since  a  similar  range  of  variation  may  be  met 
with  under  normal  conditions,  as  already  mentioned. 
Most  of  the  thirteen  attacks  of  blackwater  fever  referred  to  in 
Table  24  occurred  in  individuals  who  were  regarded  as  also  affected 
with  malaria,  since  in  all  more  or  less  typical  malarial  attacks  preceded 
the  paroxysm  of  blackwater  fever,  as  a  study  of  the  clinical  histories 
given  on  pp.  176  to  246  will  show.  Such  evidence  is,  with  one 
exception  however,  clinical  only.  In  all  cases  quinine  had  been 
administered,  and  examination  of  blood  films  made  at  the  time  of 
blackwater  failed  to  reveal  the  presence  of  malarial  parasites  in  any 
case.  The  absence  during  blackwater  fever  of  any  obvious  alteration 
in  the  vulnerability  of  the  red  blood  cells  towards  quinine  lends, 
however,  further  support  to  the  view  that  no  marked  change  in  this 
respect  is  to  be  anticipated  in  malaria. 
