542  Standardisation  of  Commercial  Papain.  {ADecemYerPi9i4m' 
calls  attention  to  Datura  Tatula  and  Datura  Stramonium,  in  which 
every  analogy  points  to  the  blue  as  the  older  and  the  white  as  the 
younger  form  or  retrograde  variety.  Atropa  Belladonna  lutea  is 
another  example  of  a  plant  where  the  physiologic  unit  anthocyanin 
is  lost  or  latent,  and  this  plant  we  consider  as  a  variety  of  Atropa 
Belladonna.  The  actual  proof  of  the  relationship  between  elementary 
species  and  varieties  is,  of  course,  rarely  to  be  obtained. 
From  this  brief  discussion  on  hybridization  and  the  principles 
involved  it  seems  most  probable  that  the  occasional  annual  forms 
of  Hyoscyamus  in  the  biennial  henbane  fields  of  England  is  due  to 
natural  hybridization. 
At  this  time  I  desire  to  call  attention,  first,  to  the  importance  of 
the  determination  of  the  exact  nature  of  the  plant, — i.e.,  whether  it 
represents  an  elementary  species,  a  variety,  a  hybrid,  a  constant  or 
an  inconstant  form;  and,  second,  to  the  need  for  close  and  critical 
study  of  the  medicinally  active  constituents  as  physiologic  units. 
Following  this,  selection  and  hybridization  for  the  purpose  of  pro- 
ducing better  drugs  may  proceed  along  scientific  lines  and  inter- 
changes or  combinations  of  desired  unit-characters  formed. 
{To  be  continued.) 
STANDARDIZATION  OF  COMMERCIAL  PAPAIN. 
By  F.  W.  Heyl,  C.  R.  Caryl,  and  J.  F.  Staley. 
The  term  "papain"  is  supposed  to  describe  an  especially  prepared 
product  containing  the  enzymatic  constituents  in  greater  propor- 
tion, and  hence  having  a  higher  digestive  activity,  than  the  crude 
juice.  Thus,  in  Merck's  "  Index  "  papain  is  described  as  having  a 
digestive  power  on  blood  fibrin  of  I  :  200,  whereas  the  proteolytic 
activity  of  the  dried  juice  is  only  1  :  80.  For  the  latter  determina- 
tion no  method  of  standardization  is  suggested,  although  the  fibrin 
test  is  probably  understood. 
The  fibrin  test  is  decidedly  awkward  and  inelegant.  Further- 
more, there  are  some  important  disagreements  as  to  the  conditions 
under  which  the  test  should  be  carried  out.  In  Hager's  "Handbuch 
der  Pharmaceutischen  Praxix"  this  test 1  is  described  as  being 
carried  out  in  a  medium  made  slightly  alkaline  with  sodium 
^and  1,  640. 
