76 
of  haemoglobin  in  the  blood  plasma  is  not  increased,  the  percentage 
of  haemoglobin  in  the  urine  is  low,  reaching  to  o'g  per  cent,  in  one 
case  (25)  and  lying  in  the  remaining  six  cases  between  0'4  per  cent, 
and  0'03  per  cent.  On  the  other  hand,  in  the  twelve  observations  in 
which  the  amount  of  dissolved  haemoglobin  in  the  blood  plasma  was 
increased,  the  percentage  of  haemoglobin  in  the  urine  was  much 
higher,  ranging  between  0-4  per  cent,  and  3-1  per  cent. 
To  sum  up,  then,  we  may  say  that,  in  the  observations  made  in 
blackwater  fever  while  the  urine  in  the  bladder  still  contained  haemo¬ 
globin,  an  increased  amount  of  dissolved  liaemoglobin  in  the  blood 
plasma  was  observed  m  most  but  not  m  all  cases. 
We  now  turn  to  the  second  problem:  is  haemoglobinaemia 
ordinarily  attended  with  haemoglobinuria,  and,  if  so,  what  quantita¬ 
tive  relationship  between  the  two  conditions  exi.sts?  To  determine 
this  point  it  was  necessary  to  produce  haemoglobinaemia 
experimentally. 
Method.  Oxalatcd  rabbit’s  blood  was  centrifugalised,  the  super¬ 
natant  plasma  pipetted  off,  and  the  red  cells  laked  by  adding  a  small 
amount  of  distilled  water.  To  the  solution  thus  obtained  an  amount 
of  solid  sodium  chloride  was  added  in  amount  sufficient  to  make  the 
proportion  of  this  salt  0'85  per  cent.  The  red  cell  stromata,  which 
were  precipitated  by  the  addition  of  sodium  chloride,  were  then 
removed  by  centrifugalisation,  a  dark  red  liquid  being  obtained.  The 
percentage  of  haemoglobin  in  this  solution  was  determined  by  means 
of  a  haemoglobinometer  reading,  and  a  measured  volume  of  the 
solution  injected  into  a  vein  of  the  ear  of  the  rabbit  supplying  the 
haemoglobin.  At  the  end  of  three  to  six  or  more  minutes,  about  ten 
drops  of  blood  from  the  opposite  ear  were  allowed  to  fall  into 
O'  I  c.cm.  of  I  per  cent,  potassium  oxalate  solution,  the  volume  of  the 
mixture  being  carefully  measured.  This  was  then  centrifugalised,  and 
the  percentage  of  haemoglobin  in  the  plasma  determined  usually  by 
matching,  under  a  comparison  spectroscope,  with  a  solution  of 
haemoglobin  of  known  concentration,  though  when  the  concentration 
of  haemoglobin  was  high  a  haemoglobinometer  determination  was 
sometimes  made  instead.  At  later  periods  similar  estimations  of  the 
haemoglobin  content  of  the  plasma  were  carried  out.  In  the  same 
way  the  haemoglobin  content  of  the  urine  was  determined,  and  the 
