Am.  Jour.  Pharni. 
Sept.,  1887. 
Mexican  Lign  Aloes. 
451 
that  it  has  almost  disappeared  from  Cuantla  Morelos,  where  it  for- 
merly abounded.  The  pure  oil  is  obtained  by  M.  Delpech  by  distilla- 
tion by  steam  heat,  and  costs  20  to  25  francs  per  kilogram ;  an  in- 
ferior oil  prepared  by  the  natives  is  sold  for  a  lower  price. 
The  structure  of  the  wood  presents  the  following  characters.  The 
fibres  are  of  medium  length  with  the  walls  only  slightly  thickened ; 
<each  is  divided  transversely  by  numerous  thin  walls  constituting  a 
kind  of  ligneous  parenchyma,  of  which  the  whole  wood  is  formed. 
On  transverse  section  the  fibres  are  seen  to  be  all  of  equal  thickness, 
so  that  it  is  not  easy  to  distinguish  the  zones  of  growth  of  the  wood. 
The  vessels  are  of  large  size,  with  numerous  transverse  trabecular, 
wrhich  on  longitudinal  section  are  seen  to  give  a  moniliform  appear- 
ance to  the  vessels;  they  are  dotted  all  over,  the  dots  being  surrounded 
with  areolar. 
The  medullary  rays  are  thin,  and  have  two  to  four  courses  of  cells 
in  thickness.  It  is  chiefly  in  the  fibres  and  medullary  rays  that  the 
nearly  solid  odorous  substance  occurs.  It  is  of  a  yellowish  resinoid 
aspect  under  the  microscope,  and  fills  them  either  wholly  or  partially. 
All  the  fibres,  however,  do  not  contain  it,  and  it  is  most  abundant 
where  the  wood  is  streaked  with  dark  veins.  This  matter  is  soluble 
in  alcohol,  so  that  the  wood  treated  with  spirit  becomes  transparent 
under  the  microscope.  In  the  green  and  healthy  state  the  wood  pre- 
sents the  same  appearance,  without  any  trace  of  oil,  although  at  the 
same  time  the  oil  may  be  perceived  in  the  fruits  and  bark  by  rubbing 
them.  In  M.  Leon  Marchaud's  memoir  on  the  "  Organization  of  the 
Burseracew"  a  somewhat  similar  occurrence  is  mentioned.  The  resin- 
ous and  perfumed  matter  of  Balsamodendron  Myrrha,  B.  africanum 
and  Protium  obtusifolium  is  localized  in  the  pith  of  the  young  branches 
to  some  degree,  but  is  abundant  in  the  bark  and  pericarp  of  the  fruits 
of  these  plants. 
The  oil  of  lign  aloes  has  been  examined  by  Messrs.  Verneuil  and 
Poisson.  Their  experiments  show  that  the  wood  cut  into  shavings 
readily  yields  the  oil  by  distillation  with  steam,  7  to  9  per  cent,  being 
thus  obtained,  and  the  wood  when  dry  is  then  found  to  be  free  from 
odor. 
When  the  oil  is  dried  over  chloride  of  calcium,  it  distils  over 
almost  entirely  between  189°  and  192°,  a  small  quantity  of  a  resinous 
body  of  a  much  less  volatile  character  remaining  in  the  still.  It  is 
an  oxygenated  body  having  the  formula  2  (C10H8)  5  H2Q,  this  for- 
