Persons  attach  such  different  names  to  colors  that  a  decision
as  to  color  blindness  cannot  be  safely  arrived  at  by  simply
showing  a  color  and  asking  its  name.  The  best  plan  is  to-
take  a  heap  of  worsted  of  all  tints,  select  one,  say  a  red,  and
tell  the  man  to  put  alongside  it  all  those  of  the  same  color,
whether  of  a  lighter  or  a  darker  shade;  if  red  blind  he  will
select  not  only  the  reds  but  the  greens,  especially  the  paler
tints.  About  one  man  in  eight  is  more  or  less  red  blind.
The  defect  is  much  rarer  in  women.
