34 
lied  BarL 
Joiii'.  IMiarm. 
J;iii.,  IS82. 
really  an  excretory  produet  of  vegetation,  a  j)art  used  uj)  and  brought  by 
contact  Avith  the  air  into  a  state  in  whicli  it  can  no  longer  be  serviceable  to 
the  living  plant  and  from  which  it  degenerates  by  a  still  further  degrada- 
tion into  hiwms,  as  we  have  reason  to  conclude,  both  from  following  out  the 
above  experiments  on  the  changes  of  colors  to  their  last  result,  and  from 
observing  analogous  changes  in  the  bark  itself  as  it  verges  towards  its  latest 
stage.    The  pieces  of  flat  red  bark  possessing  the  finest  color  are  generally 
remarkable  for  their  specific  lightness,  having  a  texture  analogous  to  that 
of  wood  that  has  lost  its  firmness  by  incii)ient  decay.    Indeed,  it  is  by  a 
process  oi'  ere macdusis  that  the  red  bark  acquires  its  color  ;  the  cincho-tan- 
iiic  acid  in  w  hich  it  abounds  having  become  oxidized  and  changed  into 
cinchona  red,  and  under  these  conditions  the  alkaloids  also  appear  to 
undergo  some  corresponding  alterations.    They  are  now  implicated  with 
resin,  which  ap])ears  to  have  also  become  oxidized  so  as  to  act  the  part  of 
an  acid,  and  is  with  difficulty  separated  ;  the  chlorophyll  has  disappeared. 
Kinovic  acid  is  still  present;  gum,  which  contributed  to  this  so-called 
resinous  character  and  was  abundant  in  the  bark  of  the  smaller  branches, 
has  undergone  a  decrease.    But  the  most  remarkable  feature  is  the  altered 
conditions  of  the  alkaloids  themselves.    Quinine,  which  formed  a  consid- 
^^i-able  proportion  of  the  whole,  is  now  greatly  diminished,  cinchonine  and 
cinclionidine  remaining  nnich  the  same.   The  total  per  centage  has  under- 
gone no  diminution,  and  an  alkaloid,  quinicine  (?)  which  was  either 
entirely  absent  from  the  smaller  quills,  or  present  in  a  feeble  projiortion, 
iiow  appears  in  a  notable  quantity. 
"  This  was  the  result  of  my  observations  on  South  American  barks  up  to 
1862.  I  then  thought  the  total  per  centage  of  alkaloids  had  not  diminished 
with  age.  The  quinicine  (?)  I  found  associated  with  aricine  (?)  or  perhaps 
the  quinia  (?)  of  Batka." 
The  chief  part  of  this  troublesome  and  noxious  residuum  T  now  suppose 
Tio  be  parieine  (1881).. 
Corresjjondencr  cfs  to  the  New  Species. 
In  order  to  show  at  once  the  importance  and  the  ditticulty  of  this  inves- 
tigation, I  add  the  tbllowing  letters,  which  complete  the  history  of  the 
subject  up  to  the  present  time. 
I  have  written  to  India  for  more  precise  botanical  details. 
Descriptioti  by  a  Planter  of  the  Pubescent  Species. 
"'This  tree  had  a  very  thick  stem  and  the  bark  also  was  very  thick.  The 
foliage  of  tlie  tree  forms  a  perfect  pyramid  ;  the  branches  drooping  dow^n 
and  then  turiiijag  up  at  the  ends.    The  leaves  are  of  a  dark  green  (^olor, 
rather  round  at  the  ends  and  very  pubescent  on  the  under  side.'' 
Analysis  of  BarJc. 
Vaiuinn.  ( 'inchomdine.  (•.'inchoDiiu/.  (iiiitiidiiie. 
3-o(»  i-10  0-24  ()-;^r) 
or  e(j[ual  to  .sulph.  (juinine  4-()7  per  cent. 
{Fro)n  Mr.  Mclvorls  Letters.) 
Ootacannmd,  Dec.  10,  1878. 
-'^  This  bark  is  taken  from  a  hair^  -leaved  variety  of  C  ofjicinalis.    It  is  a 
