400 
due  to  an  oxidation  process.  A  reduction  takes  place  in  the 
intestines  only,  and  is  probably  of  secondary  importance, 
In  our  experiments  we  adopted  Levaditi’s  and  Yamanouchi’s 
technique  ;  after  repeated  failures  to  get  any  changes  in  an  Atoxyl 
solution  when  shaken  up  for  twenty-four  hours  at  room  temperature 
with  an  emulsion  of  different  organs  (liver,  brain,  etc.),  lo  c.c.  of  a 
4  per  cent.,  2  per  cent.,  and  0-2  per  cent,  solution  of  Atoxyl  in 
physiological  saline  were  mixed  with  an  equal  amount  of  liver 
emulsion  and  kept  at  a  temperature  of  3;°  C.  After  two  hours  the 
effect  of  this  mixture  on  trypanosomes  was  tried  in  a  coverslip 
preparation.  Only  three  experiments  out  of  seven  confirmed 
Levaditi’s  and  Yamanouchi’s  observation  that  the  parasites  became 
immobilised  and  after  a  time  destroyed. 
After  dialysing  an  Atoxyl-liver  mixture  which  had  been  found  to 
have  a  marked  trypanocidal  action  in  a  coverslip  preparation  and 
concentrating  the  dialj^satc  to  the  original  volume,  when  it  became 
again  isotonic,  we  were  able  to  observe  that  the  dialysate  acted  upon 
the  parasites  in  the  same  way  as  the  original  Atoxyl-hver  mixture; 
the  slightly  acidified  dialysate  gave  a  distinct  precipitate  of  arsenic 
sulphide  when  acted  upon  by  H.,S. 
We  found  that  only  in  those  cases  in  which,  on  mixing  Atoxyl 
solution  zvith  liver  emulsion,  inorganic  arsenic  ivas  present  had  the 
mixture  a  decided  and  rapid  trypanocidal  effect  in  vitro.  On  the 
other  hand,  in  no  case  in  which  arsenic  could  not  be  detected,  could 
any  in  fluence  on  .the  parasites  he  observed. 
Similar  results  with  regard  to  the  appearance  m  the  solution  of 
inojanic  arsenic  were  obtained  when  pure  liver  oxydase  or  oxydase 
of  black  tea  was  added  in  a  sufficient  quantity  to  i  per  cent,  solution  of 
Atoxyl,  or  when  was  mixed  with  a  4  per  cent,  or  2  per  cent, 
solution  of  Atoxyl  and  exposed  for  some  time  to  a  temperature  of 
37 
If  reductase  prepared  from  yeast  was  aded  to  Atoxyl  solutions  of 
different  strengtlns,  in  some  instances  inorganic  arsenic  was  set  free 
from  the  Ato.xyl  together  with  aniline.  Tins  observation  offered  an 
explanation  of  the  presence  of  aniline,  in  the  faeces,  previously 
recorded.* 
*  Nierenstein.  Annals  of  Tropical  Medicine  and  Parasitology.  Vol.  TT,  Xo.  4.  1909 
