50 
could  not  be  detected  after  prolonged  search.  Such  cases  were, 
therefore,  of  no  value  in  settling  the  enquiry  in  question.  Only  a 
single  case  occurred  in  whicli  we  were  able  to  test  the  action  of 
quinine  on  red  cells  containing  malarial  parasites.  In  this  case,  on 
which  Observations  19  and  20,  Table  24,  were  made,  a  count  of  the 
red  cells  showed  that  about  3  per  cent,  contained  parasites. 
Method.  The  action  of  quinine  was  studied  m  the  manner 
employed  in  the  observations  recorded  in  Table  I.  Blood  obtained 
by  pricking  the  linger  was  allowed  to  fall  drop  by  drop  into  a  glass 
capsule  containing  o' 15  c.cm.  of  a  i  per  cent,  solution  of  potassium 
oxalate  until  about  i  c.cm.  had  been  collected,  blood  smears  being  made 
at  the  same  time.  The  total  volume  of  the  oxalated  blood  was  then 
measured,  and  a  haemocrit  estimation  made.  The  red  cells  were 
separated  by  centrifugalisation,  washed  and  then  added  to  O'g  per 
cent,  solution  of  sodium  chloride  in  amount  required  to  produce  a. 
2'5  per  cent,  emulsion.  This  was  mixed  with  r92  per  cent  solution 
of  quinine  bihydrochloride  and  O'Q  per  cent,  solution  of  sodium 
chloride  in  the  amounts  given  in  Table  24.  The  mixtures,  after 
stirring  with  a  capillary  glass  rod,  were  kept  in  a  water  bath  at  37°  C. 
for  three  hours,  when  smears  were  made  from  the  red  cells  contained 
in  the  last  two  tubes.  The  supernatant  liquid  after  centrifugalisation 
was  found  to  be  colourless  in  the  one  tube,  and  to  be  of  an 
exceedingly  slight  reddish  tint  in  the  other. 
The  result  was  indecisive.  At  the  close  of  the  experiment  the 
number  of  parasites  contained  in  red  blood  cells  was  diminished,  and 
those  present  did  not  stain  well.  In  addition  a  few  free  parasites 
were  seen.  It  would  thus  appear  that  the  action  of  the  quinine  salt 
was  directed  towards  the  parasites,  the  staining  reaction  of  which  was 
in  consequence  altered,  while  many  disappeared  or  became  unrecog¬ 
nisable.  Some  of  the  red  blood  cells  which  contained  parasites 
appeared,  therefore,  to  have  been  completely  destroyed  by  the  action 
of  the  quinine  salt,  for  no  red  blood  cells  could  be  seen,  which 
exhibited  a  partial  defect  of  substance.  All  the  red  blood  cells 
showed,  however,  slightly  defective  staining  reaction,  attributable  to 
the  action  of  quinine. 
Unfortunately,  we  were  able  to  make  only  a  single  experiment. 
The  problem  at  issue  cannot  be  settled  until  a  numlrer  of  sucli 
