712 
Theories  of  Blood-Coagulation 
( Am.  Jour,  Pharm. 
\      Oct.,  1921. 
serozyme  into  serozyme  henceforth  capable  of  uniting  with  cyto- 
zvme.  takes  its  course  without  any  participation  of  fibrinogen. 
Furthermore,  the  conversion  of  proserozyme,  which  as  we 
know  cannot  take  place  without  calcium  salts,  is — and  the  fact  is 
noteworthy — strikingly  favored  by  contact  with  glass.  The  capacity 
of  reacting  with  cytozyme  appears  only  after  a  much  longer  lapse 
of  time  when  the  recalcified  fluid  is  kept  in  a  vessel  coated  with 
paraffin.  Consequently,  the  influence  of  contact,  which  is  so  obvious 
in  coagulation,  is  not  exerted  through  some  interference  of  fibrino- 
gen, but  really  acts  without  any  help  of  the  latter,  as  a  factor  of 
thrombin  production.  It  is  highly  probable  that  contact  by  way  of 
absorption,  frees  the  liquid  of  some  antagonistic  substance,  most 
likely  some  protective  colloid,  which  prevented  the  serozyme  from 
reacting  with  cytozyme,  that  is,  maintained  it  in  the  inactve  con- 
dition of  proserozyme.  On  the  other  hand,  experiments  show  that 
the  presence  of  cytozyme  likewise  facilitates  such  a  liberation  of 
serozyme,  owing  to  its  strong  affinities  towards  the  latter  principle. 
To  sum  up,  we  are  now  able  to  follow  the  schema  which  in- 
dicates the  order  of  succession  of  the  phenomena. 
Schema  of  Coagulation 
Plasma  Cells  (platelets) 
fibrinogen            proseroz3'me  cytozyme 
converted  into  serozyme  liberated  by  means  of  con- 
by  means  of  calcium  and  tact  (adhesion  of  cells 
contact  along  the  wall.  along  the  wall;. 
'v  t  ,  J 
union  of  serozvme  and  cvtozvme 
i       "  " 
 >         ^-thrombin  (along  the  wall) 
fibrin 
(contact  and  calcium  no  longer  necessary) 
I  think  that  the  schema  symbolizes  quite  accurately  the  most 
prominent  features  of  the  whole  process  and  distinctly  shows  the 
sequence  of  events.  But  the  mechanism  underlying  coagulation  as 
it  occurs  under  ordinary  conditions  is  still  somewhat  more  com- 
plicated, owing  to  a  peculiar  property  of  thrombin.  Thrombin  re- 
sults from  the  union  of  serozyme  and  cytozyme,  but  these  two  sub- 
stances combine  in  variable  proportions.  The  consequence  is  that 
a  given  complex,  when  rich  in  serozyme,  is  able  to  capture  an  ad- 
ditional amount  of  cytozyme,  and,  when  rich  in  cytozyme,  which 
