Sections  through  the  synapticula  show  that  they  are  formed  as  lateral
processes  of  the  septa,  either  by  an  extension  of  the  septal  trabeculae  or  from
a  center  of  calcification  of  their  own.  In  the  former  case  a  boundary  in  the
middle  of  the  synapticulum  indicates  where  the  bundles  of  fibro-crystals  from
one  septum  have  met  those  from  the  opposite  septum.     In  the  other  case  it


ADULT  COLONY.  53

appears  as  if  the  fibers  from  tlie  synapticulum  itself  were  bracing  tbe  two
septa.  The  first  are  known  as  false  synapticula  and  the  second  as  true
synapticula,  but,  as  all  recent  writers  have  pointed  out,  there  is  no  morpho-
logical distinction  between  the  two.  Both  kinds  appear  in  any  section  of  a
corallite.  Whether  one  or  the  other  form  is  present  depends  mainly  upon  the
interval  between  the  two  septa.  Where  sufficiently  close,  as  towards  the
middle  of  the  calice,  the  interseptal  space  can  be  bridged  without  the  forma-
tion of  a  new  center  of  calcification,  while  such  is  necessary  when  the  interval
is  wide,  as  towards  the  periphery.
