384 
Current  Literature. 
Am.  Jour.  Pharm. 
Aug.,  19 1 7. 
Improvement  of  Guayule,  the  Desert  Rubber  Plant. 
Much  of  the  interest  in  the  desert  rubber  plant,  Partheniitm  argen- 
tatum,  has  centered  at  the  Desert  Laboratory  since  the  publication 
by  the  Institution  of  Professor  F.  E.  Lloyd's  book  on  this  wild  plant. 
The  volume  in  question  (Carnegie  Inst.  Wash.  Pub.  No.  139,  viii 
+  213  pp.,  46  pis.,  20  figs.),  "  Guayule:  A  Rubber  Plant  of  the  Chi- 
huahuan  Desert,"  embodies  the  results  of  an  organized  attempt  to 
bring  under  cultivation  a  hitherto  feral  desert  plant,  together  with  an 
extensive  ecological  study  of  the  same  under  normal  and  cultural 
conditions.  Careful  consideration  is  given  to  the  question  of  rate 
of  growth  and  reproduction  of  the  guayule  in  its  native  habitat,  and 
a  large  body  of  pertinent  data  is  given.  The  various  conditions  of 
climate,  soil,  vegetational  environment,  and  parasitism  affecting  the 
plant  are  presented  in  this  connection.  The  life-history,  habit,  and 
anatomical  and  histological  structure  of  the  wild  and  cultivated 
forms  are  minutely  described  and  compared,  in  order  to  secure  exact 
knowledge  concerning  the  relation  between  growth  and  the  rate  of 
rubber  secretion. 
The  wild  shrubs  are  collected  in  great  quantities  in  Mexico  and 
the  rubber,  which  grades  much  lower  than  Para,  is  extracted  by  such 
simple  processes  as  to  make  it  a  very  profitable  operation.  The  task 
of  developing  methods  of  cultivation  has  now  been  successfully  ac- 
complished by  Dr.  W.  B.  MacCallum  and  in  making  a  genetic 
analysis  of  the  plant  he  has  established  the  fact  that  it  includes  a 
large  number  of  elementary  species  which  do  not  readily  interbreed. 
The  company  under  whose  auspices  the  experiments  in  cultivation 
were  carried  out  has  purchased  7,000  acres  near  Tucson,  and  guayule 
is  now  being  established  on  this  land.  This  effort  is  notable  in  that 
it  is  a  successful  attempt  to  bring  a  wild  plant  under  profitable  cul- 
tivation, and  that  it  is  the  only  rubber-producing  plant  within  the 
borders  of  the  Lnited  States. 
Barium-Free  Salt. 
Economical  Method  of  Eliminating  the  Poison  from  Brine. 
A  method  of  removing  barium  from  brine  used  in  the  manu- 
facture of  salt  has  been  worked  out  by  the  Bureau  of  Chemistry  of 
the  U.  S.  Department  of  Agriculture.  This  method  is  now  used 
successfully  by  one  large  commercial  manufacturer,  and  it  is  believed 
will  prove  both  profitable  to  other  manufacturers  and  a  safeguard  to 
the  consumer. 
