39^ 
On  tlie  other  hand,  Ehrlich^'  and  his  collaborators  express  quite  a 
different  view  of  the  action  of  Atoxyl.  They  assume  that  Atoxyl 
changes  in  the  organism  into  a  compound  of  a  more  toxic,  and, 
therefore,  more  trypanocidal  character,  and  consider  that  the 
pentavalent  arsenic  atom  in  Atoxyl  becomes  reduced  in  the 
organism  to  a  trivalent  atom,  which  form  they  regard  as  the  active 
trypanocidal  arsenic.  Their  view  is  based  on  the  observation  that 
p-ammo-phenyl  arsen-oxide 
As  =  O 
and  di-amino-arseno-benzol 
0 
N 
111  ni 
As  =  As 
Q  Q 
(both  reduction  products  of  Atoxyl)  have  a  marked  trypanocidal 
action  vi  vitro,  whereas 
OH 
as  has  been  shown  by  a  great  number  of  observers,  does  not 
influence  the  parasites  in  vitro. 
They  believe,  therefore,  that  the  Atoxyl  molecule  is  reduced  in 
the  organism,  and  products  of  a  similar  type,  such  as  p-amiiio- 
phenyl-arsen-oxide  and  di-amino-arseno-benzol,  are  formed.  Rdhl,t 
Ehrlich’s  co-worker,  goes  so  far  as  to  state  that  the  action  of  Atoxyl 
is  only  due  to  the  formation  of  p-amino-phenyl-arsen-oxide. 
(rt)  Ehrlich  V'’erh;mdhin«en  dcr  deutschen  dcrmatologiscdien  (tesellschafl, 
X.  Congres-s,  190S. 
[b]  Ehrlich.  llerichte  cler  deut.schen  chemischen  Gesellschaft,  Jg.  XLU, 
fleft  I,  1909. 
+  Uohl.  llerl.  kliii,  Wochenschrift,  Xo.  ii,  1909. 
