313 
Some  of  the  older  trees  have  been  experimentally  tapped,  but 
1 am  told  that  the  results  of  tapping  are  not  satisfactory,  and  the 
wounds  heal  very  slowly. 
More  is  hoped  for  from  the  process  of  extracting  guttaj  trom  the 
leaves. 
Only  Dichopsis  oblongifolium  is  planted. 
R.  N.  BLAND. 
THE  MOSQUITO  PLANT. 
Report  on  the  Basil  Plant  [Ocimuin  viride)  in  relation  to  its 
effect  on  mosquitoes. 
This  investigation,  the  results  of  which  are  given  below,  origina- 
ted in  a number  of  statements  which  were  made  in  the  medical  and 
lay  Press,  to  the  effect  that  the  basil  plant  [Oclmum  viride)  pos- 
sesses the  property  of  driving  awav  mosquitoes,  and  that,  tb  quote 
the  words  which  appeared  in  the  British  Medical  yoiirnal.  (31st 
January): — "Captain  Lahrvmore  found  that  the  presence  of 
one  of  these  plants  undoubtedly  drove  the  mosquitoes  out,  and  that 
by  placing  three  or  four  round  his  bed  at  night  he  was  able  to  sleep 
unmolested^  without  using  a mosquito  net.”  (The  italics  are  mine). 
It  was  further  claimed  by  Captain  Larry.viors,  in  a letter  to  the 
Times,  that  a mosquito  placed  in  contact  with  a basil  leaf  died  in 
a few'  seconds.  While,  on  the  one  hand,  a plant  wTich  could  be 
shown  to  possess  these  properties,  would  be  a most  invaluable 
addition  to  our  means  of  protection  in  malarious  countries,  on  the 
other,  if  it  did  not  possess  them,  the  publication  of  such  statements 
would  be  apt  to  do  an  immense  amount  of  harm  by  producing  a 
false  feeling  of  security  and  by  inducing  people  to  do  away  with 
the  complete  protection  of  the  mosquito-net,  in  favour  of  the  im- 
perfect protection  of  a few  basil  plants  placed  around  the  bed.  His 
Excellency  the  Governor  therefore  requested  me  to  experiment  with 
the  view  of  ascertaining  whether  the  basil  plant  possessed  these 
properties.  And  first  as  to  the  results  of  enquiries  among  the  natives 
of  Freetown!.  1 was  unable  to  ascertain  that  a knowledge  of  this 
property  was  universal,  though  a few  people  were  to  be  found  who 
said  that  they  had  heard  that  it  would  drive  away  mosquitoes.  It 
certainly  is  not  used  to  any  extent  for  this  purpose  in  Freetown!. 
Dr.  Romer  who  was  aware  of  this  belief,  informs  me  that  he  had 
tried  it  several  times,  hung  round  his  bed.  His  impression  was  that 
while  it  appeared  to  drive  mosquitoes  away  at  first  after  a little 
they  came  back  and  he  w'as  bitten  during  the  night.  Others  who 
have  made  the  same  experiment  have  also  concluded  that  it  does 
not  offer  a permanent  protection  during  the  night. 
It  is  evident  however  that  rough  experiments  of  this  kind  are 
open  to  several  objections  and  have  very  little  scientific  value,  es- 
pecially as  the  personal  equation  enters  largely  into  them.  First 
of  all,  the  individual  may  not  be  susceptible  to  mosquito  bites,  and 
