297.  The  aiga  spirogyra  is  one  of  the  representatives  of  the  lower  algK
belonging  to  the  group  called  Conjugate.  Zygnema  with  star-shaped  chloro-
plasts,  mougeolia  with  straight  or  sometimes  twisted  chlorophyll  bands,  be-
long to  the  same  group.  In  the  latter  genus  only  a  portion  of  the  protoplasm
of  each  cell  unites  to  form  the  zygospore,  which  is  located  in  the  tube  between
the  cells.
298,  Thedesmidsalsobelongtothc  same  croup.  The  desmids  usually  live
as  separate  cells.  Many  of  them  are  beautiful  in  form.  They  grow  entangled
among  other  al^Ee,  or  on  the  surface  of  aquatic  plants,  or  on  wet  soil.  Sev.
«ral  genera  are  illustrated  in  figures  132-1J7,


CHAPTER  XV.
VAUCHERIA.
299.  The  plant  vaucheria  we  remember  from  our  study  ii.
an  earlier  chapter.  It  usually  occurs  in  dense  mats  floating
on  the  water  or  lying  on  damp  soil.  The  texture  and  feeling  of
these  mats  remind  one  of  "felt,"
and  the  species  are  &:>metimes  called
the  "green  felts."  The  branched
threads  are  continuous,  that  is  there
are  no  cross  walls  in  the  vegetative
threads.  This  plant  multipiics  it
self  in  several  ways  which  would
be  too  tedious  to  detail  here.  But
when  fresh  bright  green  mats  can  be
obtained  they  should  be  placed  i
a  large  vessel  of  water  and  set  i
a  cool  place.  Only  a  small  a
of  the  alga  should  be  placed  i
vessel,  since  decay  ^
will  set  in  more
rapidly  with  a  large  _
quantity.  F  O

several     days     one  PoTt™<.(b™.c^^arLoiv,uch.ni

should    look     for

small  green  bodies  which  may  be  floating  at  the  side  of  the  vessel
next  the  lighted  window,

SOO.  ZMg^nldi*  ot  Tknnliarlk — If  these  minute  floating  green  bodies  arc
foiuid,  a  small  dzop  of  water  containing  them  should  be  mounted  for  exami-


VAVCMERl-i.
