162 
Rennet  Ferment  in  Withania  Coagulans. 
/  Am.  Joiir.  Pharm. 
1      March,  1884. 
experiments  have  shown  that  a  5  per  cent,  solution  of  sodic  chloride 
is  the  most  efficient  in  the  extraction  of  the  active  principle  from  the 
seeds. 
There  is  no  doubt  that  the  substance  which  posssesses  the  coagulat- 
ing power  is  a  ferment  closely  resembling  animal  rennet. 
I.  A  portion  of  the  5  per  cent,  sodic  chloride  extract  loses  its 
activity  if  boiled  for  a  minute  or  two. 
II.  The  active  principle  is  soluble  in  glycerin,  and  can  be  extracted 
from  the  seeds  by  this  means ;  the  extract  possesses  strong  coagulating 
powers  even  in  small  amounts. 
III.  Alcohol  precipitates  the  ferment  body  from  its  solutions ;  and 
the  precipitate,  after  washing  with  alcohol,  may  be  dissolved  up  again 
without  having  lost  its  coagulating  powers. 
IV.  The  active  principle  of  the  seeds  will  cause  the  coagulation  of 
milk  when  present  in  very  small  quantities,  the  addition  of  more  of 
the  ferment  simply  increasing  the  rapidity  of  the  change. 
V.  The  coagulation  is  not  due  to  the  formation  of  acid  by  the  fer- 
ment. If  some  of  the  active  extract  be  made  neutral  or  alkaline  and 
added  to  neutral  milk,  a  normal  clot  is  formed,  and  the  reaction  of  the 
clot  remains  neutral  or  faintly  alkaline. 
VI.  The  clot  formed  by  the  action  of  the  ferment  is  a  true  clot, 
resembling  in  appearance  and  properties  that  formed  by  animal  rennet, 
and  is  not  a  mere  precipitate. 
Having  thus  determined  the  presence  of  a  rennet  ferment  in  the 
seeds,  I  endeavored  to  prepare  an  active  extract,  which  should  be 
applicable  for  cheese-making  purposes.  All  the  extracts  of  the  seeds 
are  of  a  deep  brown  color,  and  it  appeared,  therefore,  in  the  first  place 
desirable  to  obtain  less  highly  colored,  if  not  colorless,  solutions,  which 
should  still  be  active.  In  this  I  have  so  far  failed.  The  precipitate 
caused  by  alcohol  carries  down  the  chief  part  of  the  coloring-matter 
also,  so  that  on  being  subsequently  redissolved  the  solution  is  nearly 
as  highly  colored  as  before  the  precipitation.  The  color  can  be  removed 
by  using  animal  charcoal,  but  the  ferment  is  at  the  same  time  destroyed. 
If  all  excess  of  charcoal  is  avoided  and  the  solution  is  filtered  at  once, 
the  filtrate  is  largely  decolorized,  but  contains  only  traces  of  the  fer- 
ment. Animal  rennet  is  similarly  removed  by  filtration  through  char- 
coal. The  color  can  be  removed  by  the  addition  of  very  finely-pow- 
dered kaolin  in  a  dry  state,  but,  as  before,  the  ferment  activity  is 
thereby  destroyed.    The  same  holds  good  of  animal  rennet.  The 
