Am.  Jour.  Pharni.  \ 
November,  1901.  i 
Fruit  of  Co  cos  Nucifera. 
547 
Cambiform  cells  occur  singly,  in  rows  and  in  groups  among  the 
sieve  tubes  and  also  at  the  edges  of  the  phloem.  Those  among 
the  sieve  tubes  are  for  the  most  part  small  (about  -003  m.m.  in 
diameter),  prismatic  and  with  abundant  protoplasmic  contents  {Fig. 
6,  c1).  They  correspond  to  the  "  geleitzellen"  of  Wilhelm, 
Tschirch 1  and  other  authors  except  that  the  walls  adjoining  the 
sieve  tubes,  so  far  as  the  writer  has  observed,  are  not  pitted. 
At  the  edges  of  the  phloem,  particularly  adjoining  the  xylem,  the 
cambiform  cells  are  larger  (often  -oi  m.m.  in  diameter)  and  are 
often  empty.  The  differences  between  these  forms  are,  however,  so 
slight  and  perplexing  that  the  writer,  following  the  example  of 
De  Bary  and  Strassburger,  prefers  to  group  them  all  under  the 
head  of  cambiform  cells. 
(e)  Intercellular  spaces,  such  as  occur  in  the  protoxylem  of  many 
monocotyledinous  plants,  are  seldom,  if  ever,  seen  in  coir  fibers,  but 
oftentimes,  although  less  commonly  than  in  the  hard  shell,  the 
phloem  and  part  of  the  xylem  are  destroyed  during  growth,  leav- 
ing a  channel  in  the  bundle. 
3.  Endocarp. 
This  coat,  known  commonly  as  the  shell  (Fig.  8,  end),  is  a  dense 
aggregation  of  stone  cells,  among  which  run  longitudinally  partially 
destroyed  bundles. 
(a)  The  stone  cells  with  their  thick,  deep  yellow  walls,  branching 
pores,  the  dark  brown  contents,  present  a  striking  and  charac- 
teristic appearance.  They  are  either  isodiametric  or  strongly 
elongated,  the  latter  (often  0  2  m.m.  long)  being  usually  spindle  or 
wedged-shaped,  although  hammer-shaped,  hooked  and  various 
other  curious  forms  abound. 
A  study  of  sections  show  that  the  elongated  cells  are  arranged 
in  groups,  commonly  with  the  longer  diameters  in  tangential-trans- 
verse directions  and  are  best  seen  in  cross  sections  of  the  shell 
(Fig.  8,  qst),  but  in  some  groups,  particularly  those  adjoining  the 
bundles,  they  pass  longitudinally  about  the  shell  (Fig.  g,  1st).  It  is 
evident  from  Fig.  8  that  more  than  half  of  all  the  stone  cells  are 
tangentially-transversely  elongated.  Those  which  appear  isodia- 
metric (1st)  are  partly  cells  which  are  isodiametric  in  three  dimen- 
sions and  partly  longitudinally  elongated  cells  in  section. 
1  See  Tsckirsck,  Angewandte  Pflanzenanatomie,  Wien,  1889,  p.  349. 
