56 
Animal  Digestive  Ferments, 
/Am.  Jour.  Pharm. 
I    February,  1902. 
"  gastrites,"  and  assumed  the  gastric  juice  to  be  the  only  digesting 
fluid  of  the  body — an  illustration  of  unfounded  deductions  leading 
to  great  error  in  association  with  important  truths. 
In  the  same  year  Eberle  materially  advanced  our  knowledge  of 
digestion  by  successfully  preparing  active  artificial  gastric  juice  by 
scraping  the  mucus  from  the  inner  wall  of  the  dead  stomach  and 
extracting  the  same  with  water  and  with  dilute  acids.  He  demon- 
strated that  hydrochloric  acid  alone  would  not  digest  proteids  and 
produce  chymification.  He  however  fell  into  the  error  of  assuming 
that  mucus  itself  was  the  active  principle. 
Eberle  prepared  similar  infusions  of  other  glands,  particularly  the 
pancreas,  and  was  the  first  to  note  that  it  "  liquefied  gelatine, 
changed  starch  into  sugar,  and  emulsified  fat " — observations  for 
which  he  does  not  seem  to  receive  due  credit. 
Eberle  apparently  made  no  attempt  to  separate  the  ferment ;  but 
his  method  for  preparing  unlimited  amounts  of  artificial  gastric  juice 
removed  a  great  obstacle  in  the  path  of  progress  (scarcity  of  gastric 
juice,  as  well  as  contamination  with  other  secretions,  chyme,  etc.) 
and  paved  the  way  for  Schwann's  brilliant  researches  in  1836. 
Apparently  at  the  instigation  of  Johannes  Muller,  Schwann  repeated 
Eberle's  experiments,  and  this  in  so  thorough  and  careful  a  manner 
that  almost  all  of  his  observations  and  results  hold  true  to-day.  He 
found  ^that  the  active  principle  was  soluble  in  water  and  feeble 
hydrochloric  and  acetic  acids ;  that  acid  was  essential  for  its  mani- 
festations ;  that  free  acid  alone  had  no  solvent  power  on  coagulated 
albumen;  that  the  active  principle  was  not  in  combination  with 
acids ;  that  an  excess  of  acid  destroys ;  that  dilution  does  not 
weaken  the  activity  if  the  acidity  is  maintained  ;  that  the  action  is  a 
"  contact  action."  He  believed  the  ferment  to  be  gradually 
destroyed  during  its  action  ;  that  there  is  marked  similarity  between 
digestion  and  fomentation;  but  noted  that  no  oxygen  was  con- 
sumed  and  no  carbonic  acid  liberated  during  digestion;  that  the 
same  causes  arrest  or  destroy  both,  as  heat,  strong  alcohol;  that 
digestion  requires  acid,  fermentation,  oxygen ;  that  in  both,  small 
quantities  produce  great  changes.  He  tested  the  active  principle  in 
its  behavior  with  acids,  with  metallic  salts,  with  tannin ;  showed 
how  it  differentiated  from  albumen  by  not  being  precipitated  with 
ferrocyanide  of  potash ;  from  caseine  by  its  failure  to  precipitate  with 
ferrocyanide  and  acetic  acid  ;  and  that  it  differs  from  "  salivin  "  and 
