For,  although  it  is  confidently  anticipated  that  the  evidence  now  brought
forward  must  materially  assist  in  securing  to  the  sponges,  eventually,  a
general  recognition  of  their  intimate  relationship  to  the  Choanophorous
section  of  the  Flagellate  Infusoria,  it  can  by  no  means  be  said  that  such  an
affinity  is  at  the  present  date  universally  recognized.  On  the  contrary,
the  balance  of  contemporaneous  scientific  opinion  favours  the  relegation
of  this  organic  group  to  the  division  of  the  Metazoa,  though  upon  grounds
which,  plausible  as  they  seem  to  be  upon  the  surface,  are  fundamentally
purely  artificial  and  untrustworthy.
In  order  to  arrive  at  a  position  permitting  a  thoroughgoing  and
impartial  appreciation  of  the  very  voluminous  and  conflicting  evidence
that  has  been  amassed  with  reference  to  the  much  debated  affinities  of


144  NATURE  AND  AFFINITIES  OF  THE  SPONGES.
the  sponges,  it  is,  before  all  things,  desirable  to  commence  with  an  exami-
nation of  the  earlier  periods  of  their  intelligibly  recorded  history,  and
thence  to  trace  forwards,  link  by  link,  those  consecutively  recorded  data
which  have  led  up  to  the  present  controversial  position  of  the  question.
As  an  initial  step  in  this  direction,  it  is  worthy  of  remark  that  the
conclusive  demonstration  of  the  very  animal  nature  of  the  Spongida  has
only  been  accomplished  within  the  present  generation  ;  for  while  originally
premised  by  Marsigli  at  the  commencement  of  the  eighteenth  century,
and  subsequently  advocated  by  Ellis  and  Solander,  Montagu,  and  Lamarck,
it  was  left  to  Grant,  Bowerbank,  Carter,  Lieberkuhn,  and  Dujardin  within
these  later  limits  to  produce  the  actual  proofs  of  their  animal  organization.
