242 
Quebracho  Bark. 
(  Am.  Jour.  Pharm. 
t      May,  1881. 
line  of  the  cross  section,  and  are,  in  part,  combined  with  them  in 
groups  or  occur  isolated  throughout  the  bark.  These  peculiar  cells, 
which  aggregate  particularly  in  the  inner  portion  of  the  bark  and 
which  cause  its  fibrous,  splint-like  structure,  prove  themselves  true 
sclerenchyma  fibres  of  considerable  length,  and  are  characterized  by 
being  surrounded  by  a  closed  integument,  which  consists  of  numerous 
small  cells  and  each  of  which  contains  an  oxalate  crystal.  These 
integument  cells  surround,  as  well  upon  the  cross  as  upon  the  longi- 
tudinal section,  the  contour  of  the  thickened  fibres  most  closely,  and 
are  organically  connected  with  them,  so  that  the  separate  fibres,  iso- 
lated from  the  tissue,  present  an  over-surface  consisting  entirely  of 
these  small  crystal  cells. 
The  occurrence  of  these  spindle-shaped  fibres  covered  with  crystal 
cells,  accompanied  by  the  approximately  parenchymatous  stone  cells, 
which,  upon  a  longitudinal  section,  appear  through  the  cork  as  bright, 
punctate  cells,  is  highly  characteristic  of  the  genuine  quebracho  bark, 
and  d  priori  adapted  to  distinguish  it  from  the  false  barks  which  have 
appeared  in  commerce,  which  is  even  possible  with  the  use  of  a  strong 
lens. 
It  may  be  observed  that,  according  to  Hansen,  in  the  younger 
barks  of  the  quebracho  plant  very  deviating  anatomical  relations  pre- 
vail. The  integuments  of  the  crystal  ducts  first  exist  after  the  com- 
plete formation  of  the  sclerenchyma  fibres  and,  indeed,  from  the  sur- 
rounding parenchyma  cells.  The  formation  of  the  entire  duct  tissue 
proceeds  quite  slowly.  Cross  sections  through  younger  barks  show 
that  nowhere  a  ring  of  cells  containing  crystals  surrounds  a  younger 
fibre,  but  that  this  is  closely  surrounded  by  the  parenchyma  cells  of 
Ihe  cortical  tissue. 
The  author  subsequently  considers  the  microscopical  structure  of  the 
wood  of  quebracho,  which,  in  the  case  of  the  true  Q.  bianco,  like  the 
bark,  possesses  some  medicinal  activity,  although  to  a  very  slight 
extent,  and  together  with  the  wood  of  Q.  Colorado,  on  account  of  its 
extreme  hardness,  is  much  employed  in  its  native  country  for  building 
purposes. 
In  consideration  of  the  most  important  false  quebracho  barks  which 
have  served  as  substitutions  for  the  aspidosperma  bark  there  is  to  be 
mentioned,  in  the  first  place,  a  bark  which  has  been  much  sold  and 
applied  as  quebracho,  although  deviating  so  much  from  the  true  Q. 
bianco  bark  that  its  continued  substitution  is  scarcely  to  be  thought  of. 
