Am  Jour  Pl.arn.. )  Activitii  of  Pancreatlc  Extracts.  25 
Jan.,  ibS'l.      j  i/  c/ 
called  j9a)icreaf/c  diastase,  and  a  proteolytic  enzyme  called  trypsin. 
The  pancreas  also  takes  an  important  share  in  the  digestion  of  fats ; 
but  whether  this  power  is  due  to  an  enzyme  or  to  an  agent  of  different 
character  is  a  question  not  yet  determined.  The  })resent  paper  con- 
cerns itself  solely  with  the  amylolytic  and  proteolytic  functions  of  the 
pancreas. 
Estimation  of  the  Amylolytic  Adlvltij  of  Faiureas  Extracts:  Dlas- 
taslmetry. — The  method  adopted  by  the  author  for  this  purj)ose  con- 
sists in  ascertaining  the  quantity  of  starch-mucilage  of  known  strength 
which  can  be  transformed  by  a  unit-measure  of  a  diastasic  solution  to 
the  })oint  at  which  it  ceases  to  give  a  color  reaction  with  iodine  in  a 
unit  of  tilue  and  at  a  fixed  temperature.  The  vanishing  point  of  the 
<3olor  reaction  is  called  the  o chromic  jjolnt. 
The  amount  of  amylolytic  work  which  can  be  done,  or,  in  other 
words,  the  amount  of  standard  starch-mucilage  which  can  be  brought 
to  the  achromic  point  in  a  given  time  by  a  given  sample  of  pancreatic 
extract  is  exactly  proportional  to  the  quantity  of  the  extract  employed, 
provided  the  products  of  the  enzymosis  do  not  accumulate  in  the  solu- 
tion to  such  a  degree  as  to  interfere  with  the  action,  which  will  not  be 
the  case  if  the  starch-mucilage  used  is  sufficiently  dilute.  The  muci- 
lage used  in  the  author's  experiments  was  of  the  strength  of  1  per  cent. 
This  law  of  proportionality  may  perhaps  be  regarded  as  applicable  to 
'the  action  of  all  enzymes  which,  indeed,  having  no  power  of  growth 
or  multiplication,  conform  in  this  respect  to  the  law  which  governs 
the  action  of  ordinarv  chemical  ai^ents. 
The  fundamental  rule  governing  the  relations  of  quantity  and  time 
in  the  action  of  an  enzyme  is  that  of  inverse  j^roportion,  that  is  to  say, 
a  double  quantity  of  an  enzyme  will  do  a  given  amount  of  work  in 
lialf  the  time,  etc.  This  rule,  however,  io  apparently  modified  by 
another,  namely,  that  an  enzyme  liberates  its  energy  at  a  progressively 
retarded  rate.  In  regard  to  the  action  of  pancreatic  extract  upon 
starch-mucilage,  the  rule  of  inverse  proportion  between  quantity  and 
time  was  found  to  hold  good  within  considerable  limits,  as  shown  by 
the  folk) wing  table  giving  the  results  of  experiments  in  which  10  cc. 
standard  starch-mucilage  of  the  strength  of  1  ])er  cent,  diluted  with 
water  up  to  100  cc.  was  subjected  to  the  action  of  ])ancreatic  extract  at 
temj)erature  of  15°.  The  calculated  "  time  in  the  third  column 
was  obtained  by  taking  tiie  middk'  observation  of  each  set  as  a  stand- 
ard of  c()m])ari.son. 
