5-^ 
the  shape  of  the  leaf,  the  hairy  growth  on  the  margin  of  the  leaves, 
their  under  side,  leaf  stern,  and  the  leaf  shoots,  as  also  the  pheno- 
menon already  alluded  to  as  the  dimorphism  of  the  branches.’^  I 
hold  these  data  suffieiently  concdusive  to  demonstrate  that  the  Las 
Cascadas  rubber  tree  is  Indeed  the  true  Castilloa  elastica.  The 
fart  that  these  trees  produce  a good  yield  of  an  excellent  quality  of 
rubber  may  well  be  taken  as  contributory  evidence  in  the  same 
direction. 
As  regards  the  unquestionable  differences  of  tlu^se  trees  from  the 
C.  elastica  as  generally  described,  I cannot  say  that  I ascribe  any 
importance  to  them.  Castilloa  elastica  possesses  such  an  enor- 
mously wide  geographical  distribution — from  Lat.  6°  S.  to  Lat.  22° 
N. — it  occurs  under  so  very  greatly  varying  conditions  of  soil,  eleva- 
tion humidity  and  temperature  limits  that  it  would  be  most  extra- 
ordinary if  it  accommodated  itself  to  all  those  different  conditions 
without  at  least  some  morphological  change.  Indeed,  it  seems 
highly  probable  that  some  of  the  varying  statements  regarding  the 
growth  of  Castilloa  elastica  in  different  districts  may  find  their 
explanation  in  the  influence  upon  this  tree  of  different  climatic  con- 
ditions. To  some  extent  this  may  also  be  true  with  regard  to  the 
various  conflicting  statements  regarding  the  yield  of  rubber  obtain- 
able from  these  trees. 
On  this  question  of  the  amount  of  rubber  yielded  by  Castilloa 
elastic  i the  information  at  our  disposal  from  numerous  sources  is 
characterised  by  a degree  of  discrepancy  perfectly  appalling.  Ac- 
cording to  Cross,  a Castilloa  of  from  18  to  24  inches  in  diameter 
produces  13  lbs.  of  rubber  annually,  but  he  asserts  that  certain  ex- 
ceptional trees  may  yield  as  much  as  loo  lbs.  COLLINS  observed  that 
a 6 year  old  Castilloa  possessing  a diameter  of  19  inches  on  being 
tapped  in  April  in  the  dry  season  furnished  20  gallons  of  latex, 
from  which  49  lbs.  of  rubber  we.'e  obtained  and  he  declares  this 
an  average  yield  of  all  trees,  the  trunk  of  which  before  branching  out, 
Nreaches  a height  of  from  18  to  27  feet  above  the  soil.  In  Nicara- 
gua, it  is  found  that  from  its  sixth  or  seventh  year,  a Castilloa  tree 
yields  from  4 to  6 lbs.  of  rubber  annually  (Crawford).  Dr.  MORRIS 
states  that  a Castilloa,  wlien  first  tapped,  should  yield  16  lbs.  of 
rubber.  In  Mexico,  it  appears  to  be  generally  assumed  that  Cas- 
tilloa trees,  when  from  4 to  5 years  old,  will  produce  an  average 
yield  of  6 lbs.  of  rubber.  However  the  Bureau  dTnformations 
.Agricoles  du  Mexique  ” is  rather  more  careful,  giving  the  yield  of 
the  trees  in  question  as  amounting  to  from  4 to  5 lbs.  of  latex, 
corresponding  to  2 lbs.  6 ozs.  o^  rubber. 
J.  H.  H.VRT  f rrinidad)  slates  the  yield  of  Castilloa  as  amount- 
ing to  2 to  6 lbs.,  but  from  quite  a recent  communication,  I take  it 
that  an  experimental  tapping  of  one  of  his  largest  trees  only  pro- 
duced about  14  ozs.  of  rubber. 
According  to  these  above  set  out  statements  we  would  have  to 
come  to  the  delightful  conclusion  that,  from  its  sixth  or  seventh 
year,  Castilloa  elas'ica  will  yield  fro  n 6 to  49  lbs.  of  rubber  annu- 
ally. 
On  the  other  hand,  we  have  the  results  of  the  experiments  of 
