A&4SZ£m£]        The  Phenomena  of  Catalysis.  511 
reactions  depends  on  the  concentration  of  the  reacting  particles 
(molecules  or  ions,  or  whatever  they  may  be).  It  is  not  difficult 
to  find  in  all  cases  of  catalysis  the  probability  of  an  increased  con- 
centration which  is  attributable  to  the  catalyst.  This  is  plain  in 
such  a  case  as  platinum  sponge  and  surface  or  solid  catalyzers,  for 
the  absorption  and  adsorption  of  gases  in  such  cases  are  well  known. 
It  is  only  a  step  along  the  path  of  this  illustration  to  see  possible 
intermediate  physical  and  chemical  compounds  as  concentrations 
of  one  or  both  of  the  reagents.  Solid  thoria  catalyzes  many  organic 
reactions,  so  also  does  dissolved  aluminum  chloride.  In  the  former 
case  the  physicist  would  grant  the  formation  of  adsorption  com- 
pounds, and  in  the  latter  case  the  chemist  recognizes  the  temporary 
formation  of  intermediate  chemical  addition  products  with  the  alu- 
minum chloride.  If  we  look  at  these  two  cases  as  cases  of  increased 
concentration  of  the  reacting  reagents,  the  possibility  of  coordina- 
tion is  clear. 
The  reactions  in  living  matter  (plant  and  animal)  are  very  com- 
monly catalyzed.  Many  of -the  catalysts  have  been  named  and 
have  been  isolated  in  more  or  less  pure  form.  Malt  diastase,  which 
brings  about-  the  dissolving  or  hydrolyzing  of  starch,  is  such  a 
catalyst.  By  its  action  in  the  germinating  grain  or  seed,  the  reaction 
of  the  break-down,  dissolution  or  solution  of  the  starch  is  made 
rapid.  The  starch  would  be  useless  without  this  catalyst,  and  it  is 
not  used  up  by  the  reaction.  This  process  is  not  confined  to  the  cell 
or  seed.  It  may  be  carried  out  in  the  laboratory.  For  example, 
a  large 'mass  of  nearly  solid  starch  paste  may  be  made  to  rapidly 
liquefy  by  the  introduction  of  a  very  small  quantity  of  diastase. 
The  enzymes  ptyalin,  invertin,  emulsion,  pancreatin,  pepsin,  and 
a  score  of  others,  are  quite  analogous.  They  each  catalyze  some 
reaction  characteristic  of  some  living  process.  Albumen  and  similar 
albumenoid  matter  is  rendered  soluble  or  assimilable  by  the  catalytic 
action  of  pepsin,  for  example.  The  reaction  is  not  a  simple  one  be- 
tween the  pepsin  and  the  albumen,  but  the  latter  causes  the  albumen 
to  react  with  the  water  present  and  hydration  occurs.  A  perfect 
explanation  of  this  catalysis  in  life-reactions  is  probably  not  yet 
possible,  but  in  looking  for  analogies  of  our  apparently  simpler 
cases,  we  are  struck  with  the  force  of  the  fact  that  these  digesting 
catalysts  are  known  to  absorb  on,  or  absorb  in  the  organic  matter 
whose  dissolution  they  catalyze.  For  example:  if  fibrin  be  sus- 
pended in  gastric  juice  (which  contains  some  of  these  organic 
