AmApX  i9^m'  J"       The  Pharmaceutical  Chemist.  229 
tine.  The  aconitine  itself  is  very  easily  affected  by  heat,  especially 
in  the  presence  of  moisture,  and  decomposes  into  various  other 
bodies  which  possess  quite  different  physiological  action.  One  can 
obtain  concordant  results  on  repeated  chemical  assays,  and  find  that 
they  fail  entirely  to  agree  with  the  physiological  activity  as  de- 
termined by  tests  on  animals.  Both  the  physiological  tests  and  the 
chemical  assay  seem  to  be  affected  by  the  presence  of  secondary 
alkaloids.  The  present  situation  as  regards  the  determination  of 
the  activity  of  aconitine  preparations  is  in  a  very  unsatisfactory 
state. 
For  over  100  years  we  have  known  that  the  most  important 
alkaloid  of  opium  is  morphine,  but  only  within  the  past  10  years 
have  we  come  to  a  definite  understanding  of  its  chemical  constitu- 
tion, and  though  at  present  morphine  is  worth  $200  per  pound,  there 
is  no  commercially  available  process  for  producing  it  synthetically. 
Then  there  is  that  class  of  substances  known  as  enzymes,  typified 
among  medicinal  agents  by  pepsin,  pancreatin,  and  diastase.  We 
have  for  years  used  these  products,  particularly  pepsin,  as  an  aid  to 
imperfect  digestive  activity,  but  do  not  yet  know  their  exact  con- 
stitution. Most  extensive  investigations  have  been  pursued  regard- 
ing the  nature  of  pepsin,  and  it  has  been  possible  to  produce  a 
material  under  this  name  of  such  strength  that  one  part  will  digest 
50,000  parts  of  coagulated  egg  albumin,  showing  a  tremendous  power 
of  protein  digestion.  Even  here  apparently  the  limit  is  not  reached, 
and  we  have  not  succeeded  in  isolating  any  definite  substance  whose 
chemical  identity  we  can  establish. 
Pancreatin  is  known  to  be  a  mixture  of  several  different  en- 
zymes, but  we  are  no  better  acquainted  with  the  constitution  of  any 
of  them  than  we  are  with  that  of  pepsin.  Besides  these  substances 
there  are  numerous  other  enzymes  of  more  or  less  importance  that 
occur  either  in  vegetable  or  animal  life,  and  many  of  which  un- 
doubtedly have  important  roles  to  play  in  connection  with  vital 
processes,  and  as  we  come  to  understand  them  better  we  may  find 
some  of  them  of  great  service  in  dealing  with  diseases  that  are  now 
but  imperfectly  understood. 
In  investigating  enzymes  we  are  struck  with  the  similarity  in 
many  respects  between  catalytic  action  of  these  organic  substances 
and  those  inorganic  colloidal  solutions  of  metals  that  are  quite  ex- 
tensively advocated  as  remedial  agents.  For  instance,  both  are  ren- 
dered inactive  by  boiling  and  are  affected  by  the  reaction  of  the 
