lage,  white  fibro-cartilage,  yellow  elastic  cartilage,  and  cellu-
lar cartilage.
FIG.  22.
Hyaline  cartilage.
Hyaline  cartilage  (Fig.  22)  occurs  in  the  costal  cartilages,
the  articular  ends  of  bones,  the  nasal  cartilaginous  septum,


54


THE  TISSUES.
the  larger  cartilages  of  the  larynx,  the  trachea  and  bronchi,
and  in  the  embryo  is  the  precursor  of  most  of  the  bones.  The
cells  are  prominent  and  rounded,  with  large  nuclei  and  dis-
tinct capsules,  and  are  imbedded  in  an  apparently  homogeneous,
hyaline,  tough  matrix,  which  yields  chondrin.  Instead  of
being  really  homogeneous,  the  matrix  is  said  to  have  a  delicate
fibrillar  structure.  The  means  or  channels  by  which  nutrient
fluids  can  penetrate  to  the  interior  of  hyaline  cartilage  for  its
nutrition  are  not  known.  The  cartilage-cells  divide  in  two
within  the  capsule  of  the  parent-cell,  which  is  thus  as  it  were
cast  off,  and  each  daughter-cell  then  acquires  a  new  capsule.
By  the  repetition  of  this  process  t\vo  or  three  generations  of
cells  may  sometimes  be  found  within  the  remains  of  the  cast-
off  capsule  of  the  single  original  parent-cell.  The  capsules
thus  cast  off  are  gradually  transformed  into  the  matrix,  which
is  partly  developed  in  this  way.  The  ground-substance  near
the  cells  stains  differently  from  that  more  remote.  Owing  to
their  mode  of  division  the  cells  in  costal  cartilage  tend  to
occur  in  groups  ;  in  articular  cartilage  they  form  rows  perpen-
dicular to  the  surface.
