3-6 
possible  !or  the  individual  to  remain  in  the  room.  It  is  probable, 
however,  that  cones  made  of  powdered  basil  would,  when  burnt 
have  I he  effect  of  driving  mosquitoes  away,  and  to  this  extent  might 
be  found  useful. 
In  conclusion  I wish  to  express  my  indebtedness  to  Dr.  HoOD, 
Senior  Medical  Officer,  for  his  assistance  in  performing  the  experi- 
ments and  verifying  the  results. 
W.  T.  PROUT, 
Principal  Medical  Officer^ 
Sierra  Leone, 
Times, 
PARA  RUBBER  IN  SELANGOR, 
By  S.  Arden, 
Experimental  Plantation's  Office, 
BATU  TIGA, 
Federated  Malay  States, 
i']th  August,  igoj. 
.In  a report  on  Hevea  brasiliensis  published  some  months  ago, 
the  question  of  extracting  the  latex,  and  the  effect  of  wounding  on 
the  flow  of  latex  was  gone  into,  and  I now  intend  to  give  the 
results  of  some  further  experiments  made  with  the  object  of  veri- 
fying the  results  which  appeared  in  that  report. 
The  aim  of  the  planter  is  to  produce  the  maximum  of  latex  with 
as  little  injury  to  the  tree  as  possible  and  at  the  least  possible 
expense.  It  has  previously  been  pointed  out  that  this  tree  is, 
fortunately,  very  hardy  and  appears  to  be  little  effected  by  the 
wounding  necessary  to  obtain  the  latex,  so  that  if  ordinary  care 
is  exercised  little  or  no  injury  results;  but  a point  which  I think 
has  not  yet  received  the  attention  it  calls  for  when  deciding  what 
style  of  incision  should  be  practised,  is  that  of  the  necessity  of 
economising  the  available  tapping  surface.  Previous  experiments 
have  shown  conclusively  that  the  first  3'  of  the  trunk  from  the 
base,  contains  the  largest  amount  of  latex,  while  if  the  tapping  be 
extended  beyond  6'  from  the  base,  the  quality  of  the  latex  de- 
creases as  well  as  the  quantity,  being  much  poorer  in  the  per- 
centage of  caoutchouc  and  containing  a larger  proportion  of  resin, 
and  the  rubber  is  therefore  not  so  elastic.  It  will  be  seen,  then, 
how  very  essential  it  is  to  economise  this  somewhat  limited  tap- 
ping area,  for  no  matter  how  skillfully  the*  wounding  is  accom- 
plished the  result  will  be  a rough  and  broken  surface  which  wdll 
be  found  difficult  to  work,  while  the  disconnected  tissue  will  un- 
doubtedly interrupt  the  flow'  of  latex  if  tapping  operations  arei 
repeated  before  cicatrization  is  complete. 
The  necessity  of  taking  advantage  of  what  is  termed  “wound 
effect”  was  shown  in  the  report  previously  referred  to,  and 
recommended  that  the  wounds  should  be  re-opened  by  taking  offj 
