64  Animal  Digestive  Ferments.  {^ebruaryTim1' 
especially  if  we  restrict  ourselves  to  that  period  when  it  can  be  said 
that  the  facts  adduced  concerning  the  nature  and  behavior  and  rela- 
tions of  the  enzymes  receive  anything  like  general  recognition,  and 
their  practical  utility  realized  and  applied. 
Pepsin  was  first  officially  recognized  in  pharmacy  by  the  French 
Codex  of  1866,  as  pepsin  medicinale,  by  the  method  originally  sug- 
gested by  Schwann  and  elaborated  by  Wasmann — the  precipitation 
by  lead  acetate  and  evaporation  of  the  purified  solution  of  the  pepsin, 
and  incorporation  with  starch.  Pepsin  by  this  method  first  appeared 
in  commerce  from  French  sources. 
In  1867  pepsin  appears  in  the  British  Pharmacopoeia,  by  the 
method  originally  suggested  by  Beale. 
The  first  mention  of  any  preparation  of  pepsin  in  the  German 
Pharmacopoeia  is  in  1872 — "  wine  of  pepsin  "  prepared  from  the 
stomach.  The  first  preparation  of  pepsin  appearing  in  the  United 
States  Pharmacopoeia  is  pepsinum  saccharatum,  1880;  also  the 
liquor  pepsinae,  prepared  from  the  saccharated  pepsin.  It  was  not 
until  the  Pharmacopoeia  of  1890,  that  an  official  standard  was 
adopted  for  "  pepsin,"  and  the  strength  of  saccharated  pepsin  pre- 
pared with  this  being  increased  six  times  over  that  of  1880.  The 
U.S. P.  defines  no  method  of  manufacture  of  pepsin.  The  special 
interest  and  significance  of  the  phaTmacopceial  requirements  of 
pepsin  are  in  providing  a  commensurate  standard  of  activity  and 
practically  complete  solubility. 
It  is  interesting  here  to  note  the  digestive  strength  of  these  various 
official  preparations  of  pepsin — the  French  forty  times  its  weight  of 
moist  fibrin  with  lactic  acid;  the  British  one  hundred  times  its 
weight ;  the  U.S.P.  pepsin  three  thousand,  and  the  saccharated  three 
hundred  times  its  own  weight  of  coagulated  albumen.  As  for  the 
pepsin  of  commerce,  Boudault's  is  stated  to  convert  four  times  its 
weight ;  Scheffer's  saccharated  digesting  from  ten  to  fifteen  times 
its  weight  of  coagulated  egg-albumen  in  from  five  to  six  hours. 
Scheffer's  process  and  Scheffer's  pepsin  may  justly  be  character- 
ized as  marking  an  epoch  in  the  production  of  pepsin  by  a  method 
admirably  adapted  for  commerce.  It  had  the  great  merit  of  employ- 
ing reagents  innocent  in  themselves  and  strongly  antiseptic,  and  this 
is  especially  advantageous  from  the  fact  that  the  precipitate  or 
magma  which  is  collected  is  so  strongly  impregnated  with  the  salt 
that  either  in  the  moist  or  pressed  form  it  retains  its  properties  under 
