17 o  The  Apocynaceae  in  Materia  Medica.  {^il^XwJm' 
WOODS. 
The  wood  of  a  number  of  species  of  apocynaceae  is  useful  both 
in  medicine  and  in  industrial  operations.  Those  of  Africa  and 
neighboring  islands  appear  to  be  the  most  important. 
Stem  of  the  Guachamaca. — The  Malouetia  nitida  Spruce, 
Guachamaca  toxifera  Grosourdy  is  a  small  tree  inhabiting  Vene- 
zuela. On  incision  there  exudes  from  the  cortex  a  white  latex. 
The  bark  is  the  most  active  organ,  but  generally  the  entire  branch 
is  used.  Externally  it  is  reddish-gray,  ridged  longitudinally  and 
marked  by  leaf  scars.  The  bark  is  thin  reddish,  wood  is  reddish 
in  concentric  zones  ;  pith  is  small  and  brown.  Taste  is  a  little  acrid, 
slightly  astringent  and  not  bitter.  The  cortical  parenchyma  is  rich 
in  resin  and  contains  numerous  groups  of  sclerotic  elements. 
Guachamanine  separated  by  SchifTer  appears  to  approach  curare 
but  in  action  has  not  been  sufficiently  studied. 
Quebracho. — The  wood  of  the  Aspidosperma  quebracho  is  exten- 
sively used  in  South  America  in  various  industries.  It  was  exhibi- 
ted for  the  first  time  in  Europe  at  the  Vienna  Exposition  in  1873, 
and  again  at  Paris  in  1878.  The  name  quebracho  bianco  is  in  allu- 
sion to  the  color  of  the  wood  and  not  to  the  bark.  The  wood  con- 
tains but  Kttle  tannin,  and  will  not  answer  for  the  purpose  of  tan- 
ning, but  is  highly  prized  by  the  wheelwright  and  carpenter. 
Aspidosperma  excelsa  Benth,  a  tree  of  British  Guiana  known 
as  "Yaruri"  has  a  light,  elastic  and  solid  wood,  which  is  greatly 
used  for  the  construction  of  oars. 
Aspidosperma  sessifiorum,  Fr.  Allem. — This  wood  is  esteemed  for 
building  and  carpenter-work  in  Brazil.  The  juice  which  exudes 
from  incisions  in  the  bark  in  drops,  is  caustic  and  bitter,  and  is  pro- 
bably very  toxic.  It  is  one  of  the  satin  woods.  A  number  of  trees 
which  in  the  Brazilian  provinces  are  known  under  the  names  of 
Peroba  or  Paroba,  are  probably  obtained  from  other  members  of  the 
genus  Aspidosperma.  Brazil  appears  to  be  very  rich  in  these  species, 
39  being  described.  From  the  vulgar  names  it  is  very  difficult  to 
determine  the  species. 
Ouabaia. — This  arrow  poison  of  the  Somali  tribe  of  Africa  is 
prepared  from  the  wood  of  an  Apocynaceae.  The  history  of 
this  substance  is  entirely  recent.  In  1882,  De  Rochebrune  and 
Arnaud  examined  this  drug,  but  their  investigations  were  inter- 
rupted by  lack  of  material.     In    1888,  Arnaud   isolated  from 
