4II 
colouring  matters  was  carried  out  on  mice,  a  fact  which  may  account 
for  our  inability  to  confirm  Ehrlich’s  experiments. 
Ehrlich* * * §  suggested  that  parafuchsin  may  act  as  a  prophylactic  for 
trypanosome  infection.  He  was  successful  in  preventing  infection  in 
mice  after  feeding  them  with  parafuchsin  and  then  inoculating  the 
parasites. 
We  attempted  to  confirm  these  experiments  on  large  animals. 
Two  large  horses  were  fed  on  parafuchsin.  One  of  them  received 
fifteen  grammes  daily  by  mouth,  for  thirty  days  and  died  after  having 
shown  toxic  symptoms  from  the  parafuchsin.  A  second  horse 
received  fifteen  grammes  by  mouth  for  forty-eight  days.  On 
inoculation,  it  became  infected  in  the  same  way  as  an  untreated 
animal. 
In  our  opinion,  it  is  not  necessary  to  compare  the  action  of 
colouring  matters  on  trypanosomes  with  the  action  of  Atoxyl. 
Whereas  in  Atoxyl  the  amino  group,  according  to  our  experience, 
effects  a  combination  between  the  proteins  and  the  Atoxyl  molecule, 
and  the  specific  action  on  the  parasites  is  due  only  to  the  liberated 
arsenic  ;  in  colouring  matters  the  trypanocidal  effect  is  most  probably 
due  to  the  amino  group.  Mesnil  and  Nicollet  already  expressed  the 
view  that  the  therapeutical  effect  may  be  due  to  the  presence  of 
nitrogen. 
Moore,  Nierenstein  and  ToddJ  came  to  the  conclusion  that  the 
NH^  group  is  the  active  trypanocidal  radical,  for  which  they  suggest 
the  name  ‘  trypanophobe  group.’  This  conception  corresponds  to  the 
observations  of  Loew  and  Bokomy§  on  the  influence  of  compounds 
containing  amino  groups  upon  the  multiplication  of  algae.  They 
found  that  with  an  increase  of  the  number  of  amino  groups  in 
compounds  of  the  type  of  urea  and  uric  acid,  the  noxious  influence 
upon  the  plant  increases. '  They  explain  the  observation  in  this  way  : 
that  the  protoplasm  contains  a  great  number  of  labile  aldehyde  and 
amino  groups  which  combine  alternately  with  the  amino  and  aldehyde 
*  Ehrlich.  Berl.  klin.  Wochenschrift,  1907.  Reprint,  p.  31. 
t  Mesnil  and  Nicolle.  Annales  de  Elnstit.  Pasteur,  XX,  p.  417,  513,  rgoh. 
I  Moore,  Nierenstein  and  Todd.  Annals  of  Tropical  Medicine  and  Parasi¬ 
tology,  Vol.  II,  No.  4,  1909,  p.  271. 
§  Loew  und  Bokorny.  Jour.  f.  prakt.  Chemie,  Bd.  36,  p.  272.  (Compare, 
Frankel,  loc.  cit.,  p.  29.) 
