'43 
may  be.  It  is  probable,  judging  from  the  rapidity  witli  which 
haemoglobin  disappears  from  the  circulating  blood  in  the  rabbit,  that 
our  observations,  which  were  of  necessity  few  in  number,  represent 
less  than  the  maximum  percentage.  Nor  are  our  observations 
sufficiently  numerous  to  enable  us  to  state  the  duration  of  the 
haemoglobin,  but  the  observations  available  in  Table  33  and  I'igs.  13, 
18  and  20,  suggest  that  in  blackwater  fever  the  discharge  of 
haemoglobin  into  the  blood  plasma  is  a  slow  process,  and  the 
duration  of  the  haemoglobinaemia  is  therefore  much  longer  than  in 
the  experimental  haemoglobinaemia  of  Table  35.  The  amount  of 
haemoglobin  passing  into  solution  in  the  blood  plasma  cannot  be 
fletermined.  It  would  not  be  possible  to  make  even  an  approximate 
calculation  of  this  amount  in  blackwater  fever  until  the  curve 
representing  the  degree  of  haemoglobinuria  from  beginning  to  end  of 
the  blackwater  had  been  ascertained  and  the  rate  at  which 
disappearance  of  haemoglobin  from  the  living  body  took  place 
determined.  It  is,  however,  easily  possible  to  obtain  a  figure 
representing  the  minimum  amount  of  haemoglobin  passing  into  the 
blood  stream.  For  example,  in  an  individual  whose  blood  measured 
41500  c.cm.  and  contained  45  per  cent,  of  red  cells  and  55  per  cent,  of 
plasma,  if  the  blood  plasma  were  found  on  examination  during 
blackwater  fever  to  contain  as  much  haemoglobin  as  would  be  present 
in  I  per  cent,  of  its  volume  of  red  blood  cells  in  the  moi.st  condition, 
then  the  total  amount  of  haemoglobin  discharged  into  the  blood 
plasma  would  be  not  less  than  that  contained  in  2475  x  o'Oi  =  24‘75 
c.cm.  of  the  patient’s  red  cells,  or  45  c.cm.  of  his  blood  prior  to  the  on¬ 
set  of  haemoglobinaemia.  The  amount  actually  jiassing  into  solution 
in  his  blood  plasma  would  be  greater  than  this,  for,  on  the  one  hatul, 
a  single  observation  of  his  blood  plasma,  would  not  reveal  the 
maximum  percentage  of  haemoglobin,  and,  on  the  other  hand,  the 
whole  of  the  haemoglobin  would  not  be  discharged  into  the  blood 
plasma  in  the  course  of  a  few  minutes,  as  in  the  experiments  recorded 
in  Table  35.  Since  in  the  observations  recorded  in  Table  50  the 
duration  of  individual  attacks  of  haemoglobinuria  ranged  from  four 
hours  or  less  to  four  days,  the  amount  of  blond  destruction  would 
appear  to  represent  a  considerable  portion  of  the  total  amount  of 
blood  present,  and  would  be  sufficient  to  account  both  for  the  watery 
condition  of  the  blood  generally  observed  when  the  finger  is  pricked, 
