It  is  therefore  to  be  expected  that  in  a  discussion  of  the  relation
between  the  strand  and  inland  floras  in  the  Pacific  islands  the
problem  will  be  mainly  concerned  with  the  possible  derivation  of
inland  from  littoral  plants.  In  such  a  discussion  the  relation
between  the  beach  and  inland  species  of  the  same  genus  becomes  a
subject  of  great  interest.  It  is  a  subject  that  had  a  peculiar
fascination  for  Professor  Schimper,  who  refers  to  it  more  than  once
in  his  pages ;  and  though  never  able  to  take  it  up,  he  viewed  it
as  a  very  promising  field  of  inquiry.  The  question  has  been
frequently  alluded  to  in  this  work  ;  and  it  is  especially  dealt  with
in  one  connection  in  Chapter  1 1.  It  is  there  shown  that  whilst,  as
a  general  rule,  the  seeds  or  seedvessels  of  the  coast  species  possess
great  floating  power,  those  of  the  inland  species  of  the  same  genus
have  little  or  none,  and  that  both  may  have  independent  modes  of
dispersal,  the  first  by  currents,  and  the  last  through  frugivorous  birds.
A  close  connection  between  the  beach  and  inland  floras  is
apparently  displayed  in  the  circumstance  that  quite  a  third  of  the
genera  of  the  Pacific  insular  floras  containing  littoral  species  (some
70  in  all,  excluding  the  mangroves)  possess  in  this  region   also


134  A  NATURALIST  IN  THE  PACIFIC  chap.
