53 
Dr.  Trimen,  Superintendent  of  the  Botanic  Gardens  of  Ceylon, 
and  these  results  are  as  follows: — 
5 year  old  mean  yield  of  77  trees:  2.  3 oz.  per  tree. 
0 „ 6i  ,,  2.  o ,, 
8 ,,  „ 61  ,,  I.  8 „ 
12 
My  chief  reason  for  quoting  Dr.  'I'rimen’S  hgures  is  merely  to 
call  renewed  attention  to  the  absolute  necessity  ot  carefully  ascer- 
taining the  yield  of  the  Castilloa  tree  in  any  district  in  which  it  is 
intended  to  cultivate  it.  Dr.  Trimen’s  figures  cannot  be  looked 
upon  as  representing  the  yield  of  Castilloa  elastica  anywhere  but 
in  Ceylon  or  Java,  but  they  convey  a vivid  idea  as  to  the  extra- 
ordinary degree  to  which  different  conditions  of  soil  and  climate 
may  affect  the  yield  of  rubber. 
My  own  results  obtained  at  Las  Cascadas  are  as  follows  : — 
Age  of  tree.  Yield  of  latex.  % of  rubber  in  latex.  Yield  of  rubber. 
6 
I lb. 
13  oz. 
26 
7.5  OZ. 
7 
2 „ 
5 
26 
9.6  ,, 
8 • 
3 M 
I 
29 
14.2  ,, 
1 1 
5 M 
0 M 
31 
itt).  9.7  ,, 
As  the  trees  can  with  perfect  safety  be  tapped  twice  yearly,  the 
annual  rubber  yield  may  be  taken  double  that  in  the  last  column 
of  the  above  table.  These  yields  as  regards  the  trees  of  8 and  ii 
years  of  age  respectively,  are  the  means  of  a number  of  fully  de- 
veloped trees  of  the  two  respective  ages.  The  yields  of  the  younger 
trees  above  given  were  obtained  on  tapping  two  representative 
trees  of  the  respective  ages,  and  taking  the  mean  of  the  yield  ob- 
tained as  the  real  yield,  I consider  the  above  figures  rather  below 
than  above  the  mark.  But  it  is  nevertheless  well  worth  pointing 
out  that  as  even  Castilloa  trees  of  the  same  age  are  apt  to  exhibit 
astonishing  differences  in  their  development  it  is  only  to  be  expected 
that  they  do  so  likewise  as  regards  the  quantity  of  rubber  they 
produce,  and  it  is  perhaps  not  and  altogether  safe  procedure  to 
ascertain  the  aggregate  yield  of  a rubber  plantation  by  simply  mul- 
tiplying the  number  of  trees  on  the  plantation  with  the  however 
carefully  ascertained  yield  of  a limited  number  of  trees.  It  is  fur- 
ther my  opinion  that  the  method  of  planting  and  rearing  young 
rubber  plantations,  always  speaking  of  Castilloa  elastica,  is  a matter 
deserving  of  much  closer  and  more  careful  study  than  it  has  so  far 
obtained.  The  method  of  simply  planting  out  in  a forest  clearing 
so  many  seeds,  or  seedlings,  at  so  many  feet  distance,  I consider 
altogether  inadequate.  With-  this  highly  important  matter  I propose 
to  deal  at  some  future  occasion. 
'fhe  question  regarding  the  best  method  of  tapping  the  rubber 
trees  is  one  which  just  now  is  engaging  the  attention  of  most  of 
those  occupied  in  rubber  {planting.  Of  course,  there  are  always 
the  methods  of  the  natives  to  fall  back  upon,  but  it  could  not  be 
said  that  these  are  on*the  whole  calculated  to  inspire  much  con- 
fidence, and  this  for  the  simple  reason  that  the  native  collectors 
in  all  parts  of  the  world  never  show  the  slightest  regard  for  the 
trees  they  are  tapping.  If  they  do  not  actually  cut  the  trees  down,  or 
