526       *  Plants  Yielding  Tanning  Materials.  {AmoS'^rm' 
thorn  becomes  evident.  The  hardened  or  upper  portion  of  the 
thorn  soon  shows  at  its  base  a  line  of  separation,  caused  by  a  differ- 
ence of  form  and  the  manner  of  thickening  of  the  cells  in  its  upper 
and  lower  part.  A  split  across  the  top  of  the  cushion  and  between 
it  and  the  base  of  the  spiny  portion  is  thus  formed.  The  latter 
ultimately  separates  from  its  corky  base  and  leaves  a  scar,  or  causes 
a  truncated  appearance  on  the  top  of  the  corky  cushion.  In  rare 
cases  the  spiny  portion  or  part  of  it  may  still  be  seen  adhering  to 
the  top  of  the  corky  cone.  Mr.  Barber  appends  to  his  paper  a  list 
of  plants,  the  thorns  of  which  have  basal  cork  formation.  This  list 
includes  plants  belonging  to  the  Malvaceae,  Rutacece,  Simarubece, 
RhamnaceaBy  Leguminosce>  Rosacea?,  Araliaceae,  Cactaceae  and  Euphor- 
biaceae. — Phar.  Jour,  and  Trans.,  Aug.  6,  1892,  p.  108. 
PLANTS  CAPABLE   OF   YIELDING  TANNING 
MATERIALS.1 
By  F.  E.  Mafat. 
Algarobilla. — The  pods  of  different  species  of  Prosopis,  containing 
60-65  per  cent,  of  tannin  ;  imported  from  South  America,  particu- 
larly Chili. — Leguminosae. 
Alder  [Betula  Alnus,  Linn.). — In  Europe  Alnus  glntinosa  and 
Alnus  incana,  and  in  Japan  Alnus  firma,  are  indigenous.  The  bark, 
leaves  and  fruit  contain  13  to  15  per  cent,  of  tannin;  the  36  per 
cent,  given  by  some  authorities  may  be  doubted.  The  Japanese 
alder  contains  25  per  cent,  of  tannin  and  colors  the  leather  but 
little  ;  the  European  alder  is  used  in  Russia  and  gives  a  deep  color. 
— Betulaceae. 
<(Arbousier"  (Arbutus  Unedd)  grows  in  Europe;  its  leaves  are 
used  for  tanning  in  Asia-Minor  and  contain  as  much  as  36  4  per 
cent,  of  tannin. — Ericaceae. 
"Airelle-myrtille"  {Vaccinium  Myrtillus,  Linn.). — This  plant, 
more  commonly  known  as  bilberry,  is  abundant  in  France,  Germany 
and  England.  Its  tannin  is  rapid  in  its  action,  and  3-5  kilos  of  the 
dried  and  ground  plant  will  make  1  kilo  of  sole  leather  in  a  short 
time.    The  plant  is  best  pruned  like  sumac,  the  leaves  are  not 
1  From  an  abstract  in  the  Joum.  Soc.  Chem.  Ind.,  July,  of  a  prize  essay  ; 
reprinted  from  Phar.  Jour,  and  Trans.,  August  20,  1892. 
