152 
the  clay  preceding  the  attack,  malarial  parasites  have  been  shown 
to  be  present  in  tlie  majority  of  cases,  that  is  in  62  per  cent,  to  96  pet 
cent,  of  the  attacks  investigated,  but  it  is  also  well  known  that  tlip 
actual  jicrcentagc  of  red  cells,  which  can  be  observed  to  be  affected, 
is  frec]uenlly  very  small.  If,  however,  the  haemoglobinaemia  met 
with  in  blackwater  fever  were  due  to  the  haemolysis  of  red  cells 
affected  with  malarial  parasites,  present  in  the  peripheral  blood,  then 
the  affected  red  cells  would  be  in  such  numbers  as  to  be  easily 
recognised.  For  example,  a  condition  of  haemoglobinaemia  in  whidi 
the  blood  plasma  contained  i  per  cent,  of  dissolved  haemoglobin  (cp. 
Obs.  ^8,  Table  34,  for  example)  would  necessitate  a  minimum  affection 
of  one  red  cell  in  every  hundred,  while  if  this  degree  of  haemoglobir: 
aemia  were  prolonged  for  several  hours  the  proportion  of  red  cdli 
affected  would  be  considerably  greater.  In  the  cases  of  blackwatei 
fe\'er  coming  under  our  observation  (Table  46)  parasites*  were  found 
in  the  jieripheral  blood  on  the  day  before  the  appearance  of  blad, 
water  in  one  or  two  cases  ;  on  the  first  day  of  blackwater  in  not 
one  out  of  nineteen  observations  (ten  attacks) ;  and  in  no  observation! 
made  during  blackwater  fever  at  a  later  date.  Observations  of  thisi 
kind  are,  however,  inconclusive  (and  the  same  objection  applies  tcl 
spleen  smears  about  to  be  described),  for  the  condition  observed] 
cannot  safely  be  assumed  to  represent  that  present  at  the  onset  of  thei 
attack.  What  is  required,  in  investigating  the  situation  in  whicli] 
laking  may  occur,  is  a  quantitative  examination  of  the  distribution  ol^ 
malarial  parasites  in  the  red  cells  made  just  before  haemoglobin 
aemia  commences.  In  those  attacks  in  which  haemoglobinuria  is  tli(| 
direct  sequence  of  a  single  dose  of  quinine  the  time  at  which  haemoi 
globinaemia  commences  can  be  determined.  It  is,  however,  onlyiii| 
exceptional  cases  that  observations  are  likely  to  be  made  al  tbis( 
time,  since  in  the  majority  of  attacks  the  first  indication  of  blackwateij 
fever  is  the  condition  of  the  urine.  It  follows,  therefore,  that  tlif| 
data  necessary  to  determine  the  relation  of  blackwater  fever  to| 
malarial  parasites  contained  in  the  peripheral  blood  will  be  obtaineii] 
with  considerable  slowness.  Until  these  data  are  obtained  it  "'ill 
not  be  possible  to  make  any  definite  statement  as  to  the  dependencf| 
of  blackwater  upon  haemolysis,  in  the  peripheral  blood,  of  red  cell 
'1‘  .“Vljout  five  thousand  red  cells  were  examined  in  each  film. 
