One  of  the  patients  .siin'ering-  from  blackwater  fever  (Case  5) 
denied  that  he  had  ever  had  malaria;  he  liad,  however,  an  enlarged 
spleen,  the  lower  border  of  which  projected  about  one  inch  below  the 
costal  margin.  With  this  exception  all  the  patients  coming  under 
observation  with  blackwater  fever  had  in  the  past  suffered  from 
repeated  malarial  attacks  (Table  49,  Col.  2).  Although  the  diagnosis 
appeared  to  have  been  in  all  cases  purely  clinical,  there  is  no  reason 
to  doubt  its  accuracy  (cp.  Table  47). 
In  attempting  to  interpret  the  significance  of  the  preliminary 
illness  above  referred  to  we  are  met  with  the  difficulty  that  it  is 
unfortunately  impossible  in  the  present  state  of  our  knowledge  to 
identify  malarial  pyrexia,  and  thus  to  distinguish  in  all  cases  this  form 
of  pyrexia  from  non-malarial  pyrexia  occurring  in  malarial  subjects. 
The  difficulty  is  connected  with  our  ignorance  of  the  mechanism  of 
production  of  malarial  pyrexia.  In  the  same  way  we  have  no  means 
of  ascertaining  if  the  pyrexia  of  blackwater  fever  is  itself  of  malarial 
origin  or  not.  It  is  equally  impossible  in  the  present  state  of  our 
knowledge  to  determine  the  significance  of  the  association  existing 
between  blackwater  fever  and  malaria. 
In  all  cases  of  blackwater  fever  coming  under  our  observation 
quinine  was  taken  prior  to  the  attack,  which  it  directly  preceded 
(Table  50,  p.  247).  The  relation  between  the  two  was  usually  quite 
distinct,  as  for  example  in  Cases  i,  2,  6,  and  14a.  The  interdependence 
of  the  two  is  not,  however,  a  simple  one,  for  in  all  but  five  cases 
(i,  4,  6,  II  and  14)  quinine  had  been  administered  for  one  or  more 
days  before  ihe  appearance  of  blackwater,  but  witliout  effect  as  far 
as  the  production  of  blackwater  was  concerned.  In  Case  7a  (p.  195) 
the  administration  of  quinine  was  observed  by  the  patient  to  be 
followed,  some  days  before  the  attack  of  blackwater,  by  a  sudden  rise 
of  temperature  attended  with  constitutional  symptoms  closely 
resembling  those  accompanying  a  previous  attack  of  blackwater  fever, 
though  no  haemoglobinuria  made  its  appearance.  It  will  be  noted 
also  that  in  five'eases  (4,  8,  10,  12,  14a,  Table  50)  it  was  deemed 
advisable  to  give  quinine  shortly  after  the  disappearance  of  black 
water.  In  two  of  these  cases  (12  and  14a)  no  relajise  occurred.  In 
two  other  cases  (4  and  8)  slight  relapses  occurred,  which  did  not  bear 
any  definite  relation  to  the  time  of  administration  of  quinine.  In 
the  remaining  case  (10)  a  remarkable  series  of  .slight  relapses  occurred. 
