THE  INCREASE  OF  INSANITY  471

condition  through  both  parents)  it  tends  to  be  reproduced  by
descendants.  So  also  normality  appears  strongly  dominant  over
imbecility ;  but,  when  the  latter  is  derived  through  both  parents,
normality,  like  black  eye-colour,  becomes  less  dominant  and  the
alternative  condition  tends  to  be  reproduced — to  become  patent.
772.  In  every  civilized  country,  during  the  last  half  century,
the  number  of  persons  registered  as  insane  has  increased  out  of
all  proportion  to  the  increase  of  the  general  population.  For
example,  in  Ireland,  "while  one  person  in  every  657  of  the  popula-
tion was  registered  as  insane  in  the  year  1851,  the  proportion  had
risen  to  one  in  178  in  1901." 1  There  is  now  one  officially  known
lunatic  to  301.32  individuals  of  the  general  population  as  against
one  to  335  nine  years  ago,  and  one  to  536  in  1859." 2  "From  1st
of  January  1858  to  1st  January  1908  the  total  number  of  lunatics
officially  known  to  the  Board  .  .  .  has  increased  from  5,824  to
16,288,  showing  an  increase  of  10,464.  .  .  .  Since  1858  the  number
of  lunatics  under  the  protection  of  the  Board  has  increased  180
per  cent."  3  Opinions  differ  as  to  the  cause  of  the  increase.  Some
of  it,  or  most  of  it,  is  undoubtedly  due  to  a  more  complete
registration.4  But  probably  some  of  it  is  due  to  actual  multiplica-
tion.5 We  possess  no  data  on  which  it  is  possible  to  found  a

1  Macpherson,  Edinburgh  Medical  Journal,  May,  1903,  p.  398.
2  Fifty-fourth  Report  of  the  Commissioners  in  Lunacy,  1901,  England  and  Wales.
3  Op.  cit.,  Scotland.
4  See  The  Fiftieth  Report  of  the  General  Board  of  Commissioners  in  Lunacy  for
Scotland,  pp.  9  et  seq.
