1 
6o 
juice,  opaque,  and  very  similar  to  that  of  the  mammal,  though  when 
administered  internally,  it  produces  lethargy,  from  its  being  trans- 
formed in  the  stomach,  into  rubber. 
This  opaqueness  is  due  to  the  presence  of  numerous  globules 
of  a matter,  which,  when  dry,  turns  elastic,  and  which  is  held  in 
suspension,  in  an  aqueous  fluid,  clear,  and  having  the  appearance 
of  an  emulsion.  'Fhis  ac^ueous  fluid  contains  various  albuminous 
substances  held  in  solution. 
Pure  rubber  composed  of  these  globules,  consists  solely  of  Car- 
bon and  Hydrogon  in  defined  proportions  C4  If7- 
The  latex  circulates  by  a system  of  longiiudinal  cellular  veins 
or  vessels.  These  vessels  are  to  be  found  in  the  inner  layer  of  the 
bark,  between  it  and  the  wood  and  known  as  the  camhium.  From 
this  cambium  the  two  layers  are  formed,  the  external  producing 
the  bark,  and  the  internal  the  wood.  It  is  in  the  internal  layer 
that  these  laticiferous  vessels  reside. 
The  bark  is  usually  ten  miilemetres  in  thickness  while  the  cam- 
bium is  from  2 to  3 miilemetres. 
During  the  fruiting  season,  or  at  the  sliedding  of  the  leaves, 
that  is,  from  May  to  July,  the  milk  is  then  abundant,  and  is  then 
rich  in  rubber,  from  this  being  the  time  the  sap  descends.  During 
this  epoch,  a kilogramme  of  milk  will  produce  half  a kilogramme 
of  rubber.  When  the  sap  ascends,  the  milk  is  then  poor  in  rubber, 
is  aqueous,  producing  no  more  than  200  grammes  of  rubber  to 
every  kilogramme  of  milk. 
The  milk  from  the  branches  and  boughs,  is  always  watery,  is 
deficient  in  globules,  and  its  chemical  composition  does  not  appear 
the  same  as  that  exuding  from  the  trunk.  Milk  should  only  be 
extracted  from  healthy  trees,  adult  and  after  thsy  have  flowered. 
A tree  does  not  attain  its  full  growth  till  after  20  to  25  years, 
though  at  ten  years  a tree  can  be  bled,  but  not  before  it  has  flow’- 
ered,  at  least  twice. 
It  is  true  that  in  tlie  Amazons,  milk  is  extracted  from  trees  of 
five  years  growth,  but  as  I have  observed,  in  snull  quantity  and  of 
poor  quality,  demonstrating  the  fact  that  at  this  age,  the  latex 
coagulates  before  there  is  time  to  prepare  it,  giving  a product  of 
Very  inferior  quality. 
Taken  also  the  milk,  even  in  the  case  of  adult  trees,  above  two 
metres  from  the  ground,  it  will  tend  to  sicken  the  tree  or  to  shorten 
its  milk  producing  period.  Some  ambitious  men,  careless  of  the 
sacrifice  it  entails,  go  the  length  of  erecting  a mutd  (fixed  ladder) 
in  order  to  tap  the  upper  part  of  a tree,  a proceeding  which  should 
be  prohibited  and  which  has  been  one  of  the  causes  which  has  led 
to  the  extinction  in  some  places  of  rubber  producers. 
To  be  continued. 
