55 
111  relatiN'el}/  \'ery  small  amount.  This  occui'red  both  within  the  red 
cells,  and  when  dissolved  haemoglobin  was  used. 
With  a  \  ie\v  of  throwing  light  upon  the  nature  of  the  process  of 
destruction  of  haemoglobin  by  urine,  the  rate  at  which  destruction 
in'oceecled  was  investigated  in  the  case  of  red  cells  (Table  2O).  The 
determination  of  the  rate  of  destruction,  in  urine,  of  dissolved  haemo¬ 
globin  was  not  attempted  owing  to  the  difficulty  of  obtaining, 
especially  with  the  higher  degrees  of  destruction,  sufficient!}'  readily 
and  accurately  estimations  of  haemoglobin  in  the  presence  of  the 
colouring  matter  of  urine. 
Method.  The  mode  of  conducting  these  experiments  was  similar 
to  that  adopted  in  the  case  of  cjuinine  (Tables  17,  18  and  ig).  Four 
e.xperiments  were  carried  out  with  different  specimens  of  healthy 
urine  obtained  from  the  same  individual,  about  three  hundred  cubic 
centimetres  being  taken  for  each  experiment.  To  this,  healthy 
human  red  blood  cells  were  added  to  the  extent  of  0’488  per  cent., 
o'484  per  cent.,  o'448  per  cent,  and  0‘488  per  cent,  in  Experiments 
I  to  4  respective!}'.  The  mixture  of  urine  and  red  blood  cells  was 
then  divided  into  three  equal  parts,  which  were  placed  in  water  baths 
kept  at  temperatures  of  37°  C.,  31°  C.  and  25°  C.  respectively,  and 
were  shaken  every  fifteen  minutes  so  as  to  secure  uniform  distribution 
of  the  red  blood  cells.  At  intervals  of  half  to  one  hour  samples  of 
the  mixture  (usually  10  c.cm.)  w'ere  withdrawn  and  centrifugalised. 
The  supernatant  liquid  was  examined  for  oxyhaemoglobin  and 
methaemoglobin  bands ;  the  red  cells  were  laked  with  distilled  water, 
the  volume  of  the  solution  being  made  up  to  that  of  the  sample  and 
the  percentage  of  haemoglobin  determined  with  the  haemoglobino- 
meter  or,  if  considerable  destruction  of  haemoglobin  and  production 
of  brown  colouring  matter  had  occurred,  matched  with  a  haemoglobin 
solution  of  known  concentration,  by  the  aid  of  a  comparison  spectro¬ 
scope,  as  already  described. 
The  urine  employed  in  these  four  experiments  varied  m  respect 
of  specific  gravity  and  reaction  (cp.  Table  27).  The  former  ranged 
from  ro26  to  i'0i5,  wdnle  the  i-eaction  was  acid  in  Experiment  i, 
slightly  acid  in  Experiments  2  and  3,  and  slightly  alkaline  in  the 
fourth  experiment.  The  urine  was  perfectl}^  clear  and  free  from 
precipitate. 
