The  degree  in  which  fish  of  the  Perch  Family  possess  this
sensibility  to  colour  environment,  however  temporary,  happens
to  have  impressed  itself  upon  my  attention  more  forcibly  in  the
case  of  another  member  of  the  family,  namely,  the  American
black  bass  (Micropterus  salmoides],  than  in  that  of  the  common
perch.  The  black  bass  bears  a  strong  general  resemblance  to
the  British  perch.  Some  years  ago,  having  reared  a  number
of  these  bass  from  the  yearling  stage  in  a  disused  mill-pond,
and  desiring  to  turn  them  into  a  large  lake  for  naturalisation,
I  had  the  said  pond  drawn  with  a  net.  The  first  draught  brought
out  half  a  dozen  bass  nine  or  ten  inches  long.  The  general  tint
of  these  fish  on  back  and  sides  was  a  rich  dark  olive-green.
Placed  in  a  wash-tub,  whereof  bottom  and  sides  had  been
bleached  to  a  whitish  hue,  they  appeared  very  dark  indeed.
A  cloth  was  laid  over  the  tub  to  prevent  the  bass  leaping  out,
and  the  net  was  made  ready  for  a  second  draught.  In  fifteen
or  twenty  minutes,  when  some  more  fish  were  brought  to  the
tub,  the  first  lot  had  completely  changed  their  tint,  being
closely  assimilated  to  their  new  background.
