EDITORIAL. 
479 
ingestion  of  food,  is  in  its  pure  state  perfectly  clear  and  transparent,  almost 
entirely  devoid  of  color,  having  at  most  but  a  very  faint  yellow  tint ;  it  has  a. 
very  faint,  peculiar  odor,  and  a  scarcely  perceptible  saline-acid  taste,  and  is 
a  little  heavier  than  water.  Only  a  few  morphological  elements  can  be  per- 
ceived in  it ;  and  these  consist  partly  of  unchanged  cells  of  the  gastric  glands, 
partly  of  the  nuclei  of  these  cells,  and  partly  of  a  fine  molecular  matter  which 
is  produced  by  the  disintegration  of  these  elements.  Its  reaction  is  very 
acid  ;  it  is  not  rendered  turbid  by  boiling  ;  when  neutralized  with  alkalies  a 
slight  turbidity  may  sometimes  be  remarked.  The  gastric  juice  is  distin- 
guished from  most  other  animal  fluids  by  the  circumstance  that  it  remains 
for  a  very  long  time  undecomposed,  and  that  even  when  a  fungus  growth 
(mould)  has  appeared,  it  always  still  retains  its  most  essential  character, 
namely,  its  digestive  power. 
"The  best  method  of  obtaining  gastric  juice  in  a  state  of  the  greatest  pos- 
sible purity,  is  to  feed  dogs,  in  whom  gastric  fistula?  have  been  artificially 
formed,  with  bones  which  they  can  readily  break  to  pieces;  in  the  course  of 
from  five  to  ten  minutes  to  open  the  outer  closed  extremity  of  the  fistula ; 
and  by  means  of  a  funnel  and  catheter  to  collect  the  escaping  juice,  and  to 
Separate  it  by  filtration  from  flocculi  of  mucus,  and  any  fragments  of  food 
that,  may  be  present.  It  is,  however,  an  objection  that  a  considerable  quan- 
tity of  saliva  is  always  mixed  with  the  gastric  juice  obtained  in  this  manner." 
"  After  Eberle  had  shown  that  the  gastric  juice,  when  removed  from  the 
animal  body,  retains  the  property  of  inducing  peculiar  changes  in  the  food, 
and  that  by  digesting  the  mucus  membrane  of  the  stomach  with  extremely 
dilute  acids,  we  obtain  a  fluid  which  possesses  true  digestive  powers,  it  was 
proved  by  Schwann  that  it  is  only  the  glandular  structure  of  the  stomach 
which  possesses  the  property  of  yielding  a  digestive  mixture  with  acids; 
and  further,  that  corrosive  sublimate  throws  down  a  precipitate  from  it 
which  possesses  the  digestive  power  in  a  high  degree.  To  this  substance 
Schwann  gave  the  name  of  pepsin.  Wasmann,  who  investigated  the  subject 
even  more  fully  than  Schwann,  demonstrated  that  the  source  of  the  gastric 
juice  and  of  this  pepsin  lay  in  the  gastric  glands,  which  he  carefully  ob- 
served and  described  ;  he  likewise  attempted  to  exhibit  pepsin  in  a  purer  state. 
"  He  proceeded  in  the  following  manner :  The  glandular  layer  in  the  sto- 
mach of  the  pig,  which  extends  chiefly  from  the  greater  curvature  through 
the  cardia,  was  carefully  detached  and  washed,  without  being  cut  up;  then 
digested  with  distilled  water,  at  a  temperature  of  from  30°  to  35Q  F.  After 
some  hours,  the  fluid  was  poured  away,  the  membrane  was  again  washed 
in  cold  water,  and  then  digested  in  the  cold  with  about  six  ounces  of  dis- 
tilled water,  and  repeatedly  washed,  till  a  putrid  odor  began  to  be  deve- 
loped. The  filtered  fluid  was  transparent,  viscid,  and  without  any  reaction; 
it  was  now  precipitated  with  acetate  of  lead  or  corrosive  sublimate  ;  the 
precipitate  was  carefully  washed  and  decomposed  with  sulphuretted  hydro- 
gen ;  the  pepsin  was  then  precipitated  by  alcohol  from  the  watery  solution, 
in  white  flocks." 
u  The  pepsin  thus  obtained,  forms,  when  dry,  a  yellow,  gummy,  slightly 
hygroscopic  mass;  in  its  moist  state  it  is  white  and  bulky;  it  dissolves 
readily  in  water,  and  always  retains  a  little  free  acid,  so  as  to  redden  litmus; 
it  is  precipitated  by  ulcohol  from  its  watery  solution;  mineral  acids  induce  a 
turbidity  in  a  solution  of  neutralized  pepsin,  which  disappears  on  the  addi- 
tion of  a  small  excess  of  the  acid  ;  but  if  there  be  a  considerable  excess  of 
the  acid,  there  is  a  flocculent  deposit;  it  is  only  imperfectly  precipitated  by 
metallic  salts,  and  not  at  all  by  ferrocyanide  of  potassium  ;  it  has  been 
asserted  that  pepsin  is  coagulated  by  boiling,  but  Frerichs  has  shown  that  the 
coagulation  is  merely  dependent  on  its  admixture  with  albumen. 
<J  This  substance  possesses  the  converting  property  in  so  high  a  degree, 
that,  according  to  Wasmann,  a  solution  containing  only  one  sixty-thou- 
