Spencer. This  he  characterizes  as  "  the  truth  that  each  species
of  organism  tends  ever  to  expand  its  sphere  of  existence — to
intrude  on  other  areas,  other  modes  of  life,  other  media ;
and,  tlirongh  these  perpetually  recurring  attempts  to  thrust
itself  into  every  accessible  habitat,  spreads  until  it  reachefl
limits  that  are,  for  the  time,  insurmountable."

Mr. Spencer  here  catches  a  glimpse  of  the  universal  lav
which  I  luve  called  "  iiological  ttatiei."  *

In  the  hut  part  of  the  first  volume  Mr. Spencer  enters
■quarely  npon  the  task  of  liarmonlxlng  the  facts  of  biology
with  the  hypothesis  of  evolution. He  disposes  of  the  Special
Creation  hypothesis  In  a  somewhat  summary  but  very  au-
thoritative manner,  and  shows,  on  the  other  hand,  how  com-
pletely the  hypotliesis  of  evolution  accounts  for  all  the  fads
that  are  satisfactorily  understood. In  doing  so  ho  considers
the  ai^menu  from  classification,  from  embryology,  from
morphology,  and  from  distribution. lie  further  sliowa  that
evolution,  aa  seen  to  go  on  in  the  living  world,  is  none  other
than  the  general  cosmical  process  described  in  "  First  Prin-
dples.**  Organic  evolution  commences  with  homogeneous
organic  matler. The  Instability  of  the  organic  colloids  favors

<  Bco  "Tha  Loeil  □IttrlbuiIoD  of  Planli"  In  "Popular  Kdmc*  Uontblj,"
*eL  li,  p. SIS. I  than  dlMuuttJ  thii  qiii'Mlon  froni  the  (ftcla  of  tiw  ■■ef.cuNi^^
Ungdon,  and  carried  the  SpcnccHaa  doctrine  cvsn  Turthcr  ttiuiUT.S^icaccT  Vu
itoti  btimi  *t  tb»  Uiot;  uoMequtialed  with  tiU  "  Biology."


ivoLunoir  nr  biology. its

ehange  In  the  direction  of  the  heterogeneooii  Thb  ptinge
from  the  homogeneous  toward  the  heterogeneous  in  living
forms  is  the  process  known  as  d^erentiaiion. The  result  of
this  differentiation  is  the  multiplication  of  special  orguiB  liav*
ing  special  functions. From  the  amoeba,  whose  entire  body
maj  be  said  to  consist  of  a  single  oxgan,  its  stomach,  to  the
human  being,  with  numerous  distinct  Teasels,  nerves^  and
muscles,  wcll-deiined  limbs,  and  specialiaed  senses,  this  dif-
ferentiation is  immense. Begr^tion  here  appears  as  the
*'  physiological  division  of  labor,"  by  which  all  the  elements
of  each  organ  are  assimilated  and  the  distinctness  of  the  or*
gan  secured. Along  with  this  differentiation  there  perpet-
ually goes  a  corresponding  integration. These  terms  are  not
opposites  in  the  Spencerian  sense,  but  correlatives. Differ-
entiation must  not  be  confounded  with  disintegration  or  dis-
sipation. 