28  Isolation  of  Tetanus  Toxin.        { A^'al°^y^T' 
statements  made  in  this  brief  article,  but  I  can  only  assert  that  they 
are  based  on  careful  clinical  and  experimental  observations  and  are 
not  contradicted  by  any  recent  careful  studies. 
ISOLATION  OF  TETANUS  TOXIN.1 
Heretofore  tetanus  toxin  and  other  toxins  as  well  as  ferments 
have  defied  the  efforts  to  isolate  them  from  the  mixtures  in  which 
they  naturally  occur.  For  this  reason  we  know  little  of  the  real 
nature  and  chemical  structure  of  these  remarkable  substances ;  but 
a  way  to  progress  seems  to  have  been  found,  as  London  and  his  co- 
workers in  the  Institute  for  Experimental  Medicine  in  Petrograd 
now  report  that  under  certain  conditions  tetanus  toxin  and  pan- 
creatic ferments  may  be  carried  down  on  colloidal  particles.  They 
find  that  by  the  addition  of  17  per  cent,  of  ammonium  sulphate  to 
culture  fluids  in  which  tetanus  bacilli  have  been  growing;  by  cen- 
trifugation,  the  resulting  sediment  being  thrown  away ;  and  then  by 
the  addition  of  from  1  to  3  per  cent,  more  of  ammonium  sulphate,  a 
sediment  is  obtained  which  contains  the  tetanus  toxin.  This  sed- 
iment may  be  dried  in  vacuum  and  rinsed  repeatedly  with  am- 
monium sulphate  without  thereby  reducing  the  toxicity  of  the  toxin, 
as  minute  a  quantity  as  0.00000002  Gm.  being  fatal  for  white  mice 
in  two  days  after  subcutaneous  injection.  They  also  report  that  by 
a  similar  treatment  of  pancreatic  juice  with  20  per  cent,  ammonium 
sulphate,  the  amylolytic  ferment  may  be  secured  in  what  looks  like 
a  practically  pure  form,  while  with  30  per  cent,  the  proteolytic  fer- 
ment, and  with  50  per  cent,  the  lipolytic  ferments  are  carried  down. 
These  remarkable  results  indicate  that  under  certain  conditions, 
which  vary  in  each  case,  tetanus  toxin  and  pancreatic  ferments  at- 
tach themselves  to  particles  and  thus  become  obtainable  in  nearly 
pure  form.  This  discovery  may  mark  a  long  step  in  advance  in  the 
study  of  toxins  and  ferments  in  general,  the  same  principles  no 
doubt  being  applicable  to  many  other  toxins  and  ferments  than 
those  mentioned. 
1  Reprinted  from  The  Journal  of  the  American  Medical  Association. 
