It  was  necessary  to  uproot  and  destroy  polygamy,  bloody
religious  rites,  and  the  like,  but  it  was  vital  that  these
things  should  be  replaced  by  monogamy,  Christianity,
and  other  civilized  institutions.  Opposed  to  the  ac-
complishment of  this  profound  change  were  two  forms
of  resistance,  viz.,  physical  heredity  and  post-natal  or
social  heredity.  By  the  latter  is  meant  the  transmission
of  ideas  and  habits  from  parent  to  child  by  example
and  teaching.  The  overlapping  of  generations  secures
the  continuity  of  this  external  inheritance,  and  while  it
may  be  modified  far  more  easily  than  physical  heredity,
its  resistance  to  change  is  very  great.
Between  the  inner  constitution,  transmitted  physi-
cally, and  the  outer  habits  of  life,  transmitted  socially,
there  arises  during  a  thousand  generations  of  undis-
turbed existence  a  delicate  adjustment.  When,  there-
fore, the  attempt  is  made  to  replace  one  stream  of  social
heredity  by  another  infinitely  more  exacting,  the  inner
nature  controlled  by  physical  heredity  cannot  respond
successfully  to  the  new  demands.  This  sudden  read-
justment, however,  the  African  on  our  soil  has  been
called  upon  to  make,  at  first  under  compulsion,  then  by
pursuasion  and  assistance.  Yet  his  physical  heredity
could  not  possibly  be  modified  on  demand  to  suit  the
new  requirements.  While  he  was  a  slave  the  white
man  could  suppress  the  uprising  proclivities,  born  of
other  conditions,  but  could  not  entirely  uproot  them.
In  two  ways  only  could  an  inner  transformation  be
wrought:  (i)  by  the  slow  operation  of  selection,  and
(2)  by  race  amalgamation.
