Am   Jour.  Ph.irni. 
April,  1884. 
Characteristics  of  Vegetable  Fibres. 
223 
a.  Jute. — Cell-cavity  large,  roundish,  oval;  middle  lamella  very  narrow; 
no  lamination  ;  the  ends  always  rounded,  and  almost  always  strongly 
thickened. 
b.  Abelmoschus. — Transverse  sections  larger  than  in  a,  bounded  by 
straight  lines,  sharp-edged ;  cell-cavity  a  dot  or  line,  oval,  rarely  angular, 
smaller  than  in  a.  Fibres  of  uniform  thickness,  ends  broad,  rounded,  often 
tbiekened  ;  cell-cavity  variable,  often  reduced  to  a  line. 
2.  Transverse  sections  always  in  groups,  polygonal,  bounded  by  straight 
lines,  with  sharp  or  slightly  rounded  edges ;  cell-cavity  empty.  Middle 
lamella  broad  and  decidedly  darker  than  the  transverse  section  ;  cell-cavity 
with  constrictions,  locally  entirely  absent. 
a.  Hibiscus. — Edges  sharp  or  rounded ;  in  the  first  case  the  cell-cavity 
small,  in  the  latter  case  broader  and  oval ;  middle  lamella  sometimes  want- 
ing; transverse  sections  only  slightly  and  inconspicuously  laminated. 
Fibres  of  very  various  thickness,  not  usually  striated  longitudinally  ;  ends 
blunt  and  almost  always  thickened. 
b.  Urena  sinuata.  —Edges  sharp  ;  cell-cavity  very  small,  a  dot  or  narrow 
short  line  ;  middle  lamella  broad  and  very  distinct ;  transverse  section  not 
laminated.  Fibres  of  uniform  thickness,  rarely  striated  longitudinally  ; 
ends  rounded,  rarely  somewhat  thickened. 
II.  Monocotyledons.  Vessels  in  addition  to  bast-fibres  ;  cell-cavity  with- 
out constrictions. 
1.  Transverse  section  usually  rounded,  rarely  polyhedral;  cell  cavity 
always  round  ;  no  middle  lamella. 
a.  New  Zealand  Flax  (Phormium  tenax). — Transverse  sections  small, 
usually  round,  closely  contiguous,  polygonal,  with  rounded  edges;  cell- 
cavity  empty.  Fibres  thin,  uniform,  smooth,  rigid;  cell-cavity  small,  of 
uniform  breadth,  without  striation  or  distortion;  ends  sharp. 
c.  Manila  Hemp  {Musa  textilis). — Transverse  sections  polygonal,  with 
rounded  edges  or  roundish ;  cell-cavity  large,  roundish,  sometimes  with 
yellow  contents.  Fibres  of  uniform  thickness,  smooth,  not  striated,  with 
thin  walls  ;  ends  sharp  or  slightly  rounded.  After  combustion  of  the  fibre 
siliceous  skeletons  remain  behind  in  the  form  of  strings. 
2.  Transverse  section  evidently  polygonal ;  cell-cavity  polygonal,  with 
one  or  more  sharp  edges,  moderately  large  ;  no  middle  lamella. 
a.  African  Hemp  (Senseviera). — Transverse  sections  closely  contiguous, 
not  laminated.    Fibres  thin,  smooth,  with  sbarp  ends. 
b.  A loe.— Transverse  sections  not  very  numerous  in  a  group ;  edges 
slightly  rounded ;  cell-cavity  not  very  large,  polygonal,  often  with  rounded 
ends ;  large  spiral  vessels.  Fibres  of  uniform  thickness,  without  structure  ; 
ends  sharp  or  rounded. 
c.  Agave.— Transverse  sections  polygonal,  bounded  by  straight  lines, 
closely  contiguous;  cell-cavity  large,  polygonal;  its  edges  less  sharp. 
Fibres  rigid,  considerably  broader  towards  the  middle  ;  ends  broad,  thick- 
ened, sometimes  split. 
3.  Yucca.— Transverse  sections  polygonal,  closely  contiguous,  small, 
bounded  by  straigbt  lines;  edges  very  sharp;  cell-cavity  small,  round  or 
linear;  middle  lamella  very  evident,  fibres  narrow,  striated,  with  sharp 
ends.— Phar.  Jour,  and  Trans.,  Jan.  26,  1884,  p.  587. 
