oSobeTiQ^o''""  }    Samples  oj  ''Grey  Cinchona  Bark.  735 
belong  to  one  of  these  species  or  to  an  undescribed  species  belonging 
to  the  same  group. 
Of  those  Cinchonas  to  which  Huanuco  bark  has  been  attributed 
by  different  authorities,  C.  micrantha  and  C.  nitida  are  excluded 
by  reason  of  containing  neither  laticiferous  vessels  nor  scleren- 
chymatous  cells  in  the  cortical  parenchyma;  also  C.  macrocalyx 
because  although  it  shows  sclerenchymatous  cells  it  has  no  laticif- 
erous vessels.  The  choice  of  known  species  rests,  therefore,  be- 
tween those  of  the  group  just  mentioned.  Of  these,  C.  umhellifera 
is  characterized  by  having  very  few  sclerenchymatous  cells  and  a 
resinous  zone  under  the  periderm,  and  very  small  bast  cells,  some- 
what regularly  but  radially  arranged  in  narrow  lines,  and  the  cells 
of  the  medullary  rays  are  represented  as  broader  than  long.  Ac- 
cording to  Berg,  this  species  is  found  abundantly  in  Huanuco  bark. 
In  C.  ovata  the  cork  consists  of  colorless,  not  brown,  cells. 
This  bark  may  be,  therefore,  left  out  of  consideration,  as  in  Mr. 
B.  F.  Howard's  bark  they  are  dark  brown. 
C.  Pelleteriana  has  liber  cells  varying  much  in  diameter,  and 
also  shows  club-shaped  liber  cells  (stabformig)  in  the  bark,  and 
it  is  not  known  to  occur  in  Huanuco  bark. 
C.  purpurea  has  also  a  pale  cork  like  C .  ovata.  Like  C.  Pelleteri- 
ana, it  contains  club-shaped  liber  cells.  It  is  sometimes  found  in 
Huanuco  bark,  but  the  pale  cork  distinguishes  it  from  the  bark  under 
consideration. 
C.  Peruviana  is  not  described  by  Berg,  but  is  described  by  Vogl, 
Loc.  cit.,  p.  287,  288,  and  also  by  Planchon,  who  gives  an  illustration 
of  it  (Loc.  cit.,  p.  125).  It  is  characterized  by  Vogl  as  having  numerous 
club-shaped  liber  cells  and  crystal  cells  and  the  laticiferous  cells 
often  filled  with  thyllae.  The  laticiferous  vessels  form  a  single 
or  double  ring.  The  external  appearance  of  this  bark  is  described 
by  Vogl  as  of  a  prevailing  grey-brown  color  with  yellowish,  green- 
ish, and  whitish  patches,  with  distant  transverse  cracks  and  well 
marked  long  fissures,  and  is  of  a  cinnamon-brown  color  on  the 
inner  surface. 
Planchon  and  Collin,  Loc.  cit.,  p.  124,  state  that  the  small  quills  of 
C.  Peruviana  have  a  finely  cracked  periderm  of  a  grey  or  slightly 
bluish  tint  and  closely  adherent  to  the  liber,  the  transverse  cracks 
being  few  and  shallow.  The  larger  quills  always  present  a  more  or 
less  dark  grey  tint  and  are  characterized  by  the  presence  of  white 
patches  and  longitudinal  depressions,  which  are  more  or  less  clearly 
