rSE TEOPICAL 
AGKICULTITRIST. [June 1, 1903. 
marked that these experimeuts were made not for 
marketable purposes, but in order to see what the 
increase in yield nii^lit be in eacli successive year. 
In order to compare these figures with other--, I 
will quote those obtained by tlie writer of tiie 
article previously referred t'i. Mr. Weber gives 
the following as tiie resulfs of his experiments made 
at the plantation of ias Caacadas on the Istiimus 
of fiUiaina ; — 
Per tree. 
Five-year old trees, mean yield o' 77 trees. .2-3 oz. 
Six-year old trees do. do, 61 ,, ...2-0 „ 
Eight-year old trees do. do. 61 ,, ...18 „ 
Tweleve-year old trees do. do. 61 ,, ...4'3 ,, 
Mr. Weber states, and in this 1 quite agree, that 
' the trees can with perfect sufcty be tapped twice 
yearly ; thus th-? annual rubber yield may be 
taken at double that in the last column of the 
table.' He further observes that he considers liis 
fij»ur-^s as rather below than above the mark. It 
■will be remembered that Mr. Weber gives the 
an»ount of rubber contained in the latex at from 26 
to 31 per cent. This is far, lower than I have ever 
obtained. According to Dr. Ure and Professor 
Faraday, the percentage of pure rubber in the latex 
is 45 per cent. I have never found the milk of the 
castilloa give less than 39 per cent, and in one case, 
with unusually thin milk from an old a .d mucb- 
tapped tree, I obtained as liigh as 49 per cent. If, 
then, we take the yield of a 6-year old tree at 1 lb. 
13 ounces, as given by Mr. Weber, tire result 
would be at 40 per cent, say l\l ounces of rubber, 
which is, I think, a perfectly safe and conservative 
estimate. I have no doubt, as Mr. Weber states, 
that trees can with perfect safety be tapped twice 
a year, and though the yield may not be doubled, 
a very material increase of production will result. 
My'experiments have ishown me that trees that 
have been already bled yield their latex much 
more freely than those bled for the first time. This 
was most noticeable in operating on a number of 
trees on my own land when I found that the milk 
flowed more readily and copiously from those that 
had been apparently maltreated for years than 
from splendid trunks which did not bear a scar. It 
is also evident that the yield of the castilloa depends 
much more on soil aud climate than has been hither- 
to supposed. 
Dr. Trimen), the superintendent of the Botanical 
Grardena in, 'Ceylon, gives the following results 
Age of Tree. 
Six years 
,Seven years 
Eight years .« 
Elveu years . . 
These results bear out the statements so often 
made by those acquainted with Ceylon that the 
castilloa cannot be profitably grown there, owing 
to shallowness of the soil and the underlying rock 
bed. It may be that the climatic conditions are also 
unfavourable, so that planting of the castilloa has 
in many cases been abandoned,* 
Another cause which undoubtedly greatly affects 
the yield, or at least the free flowing of the latex, 
is the amount of rainfall in the season preceding 
the tapping. The fall of rain during the wet season 
of 1902 was up to the beginning of November not 
over 50 per cent of the rainfall in normal years. It 
is stated on reliable authority that so small a rain- 
* Ciuite a mistake so far as recent years arc eon- 
cerned.— Ed. T. A, 
Yield of 
Per cent 
Hard 
latex. 
of rubber. 
rubber. 
lb. oz. 
in latex. 
lb. oz. 
1 13 
26 
0 7-5 
2 5 
26 
U 96 
3 1 
29 
0 14-2 
5 3 
31 
1 9-7 
fall has not been known for the past 20 years. I 
am speaking of the central parts of Vera Cruz and 
the adjoining State of Oaxaca, though I believe the 
same paucity of rain was remarked in other parts. 
Cleariy owing to this deficiency of rain, many 
lar;,'e trees o!i tho property which in former years 
yielded abundanMy gave not more than half the 
former an>ou!it ob aiued, clie m'lk running slug- 
gishly and coagulating rapidly. The principal yield 
was thus furnished by the grenia (the rubber which 
dries in the cuts on the trees). As an instance of 
this from 13 trees, averaging in circumference 33 
inches, I obtained only 126 ounces of milk, which 
gave me 3 pounds 3 ounces of rubber, or 42 per 
cent, while the grenia collected from the trees 
amounted to 5 pounds 12 ounces ; total, 8 pounds 
15 ounces. It was my intention to tap all these 
trees a second time, but the bad weathei* of De- 
cember, when the heaviest rains in the year fell, 
and subsiqueuUy other occupations prevented me 
from making the desired experiment. But I am 
firmly onvinced that a triennial tapping can, with 
perfect safety, be, carried out, the trees in uo way 
suffering if sufficient time be allowed to lapse be- 
tween the two operations. —Oaxaca, March 10. 
— Modern Mexico for April. 
EUBBER PLANTING AND EXPLOITATION, 
RESULTS or BUBBER TAPPINQ AT SAN MIGUEL. 
An exact record was kept of the results of some 
recent tapping of rubber trees {Castilloa elastica) on 
the • San Miguel ' plantation, owned by the Ta- 
basco Plantation Co. (Minneapolis), Minnesota), 
located on the Macuspana river, in the state of 
Tabasco, Mexico, which are summarised below. 
There are on this estate about 400 large rubber 
trees, which were planted in the shade of cacao ard 
cofTee. The.se trees were not only grown in cacao 
and cofTee, but under the shade of ' mother ' trees 
(not rubber) planted for shading the coffee while 
the rubber was getting a start. The secretary of 
the Company, Mr. James C Fifield, in communicat- 
ing these results to The India Rubber World, 
writes: — "A fact well-known to the rubber planters 
is that trees planted in the shade require a much 
longer time to attain their maturity and full size 
than those planted in the sun. In fact, the most 
casual observer could not fail to notice the astonish- 
ing difference in size between the trees grown in 
the sun and those in the shade. It is believed that 
the size of a rubber tree has more to do with the 
amount of rubber wliicli it will produce than its 
age.'' In the table which follows is given the age of 
the trees, except that the age of those placed at 10 
and 12 years is not accurately known ; the circum- 
ference of the trees three feet from the ground ; 
the weight in ounces of the latex secured ; and the 
average yield per tree of dry rubber (including a 
small amount of scrap pulled from (he trunk of the 
tree after tapping). The details follow : — 
No. of Average Ounces Ounces 
Age. Trees. Girth. Latex, liubber 
7 years ... 257 33.80" 11.80 9.30 
8 years ... 14 37.7.'>" 20.70 14.25 
9 years ... 7 40.14" 21.28 18 
10 years ,.. 4 43.2.5" 26.75 17.50 
12 years ... 21 50.50" 40.50 28.90 
Based upon the above figujes, the rubber product 
from an acre of land containing 200 trees seven 
years old would be 112 pounds ; at eight years 6ld, 
174 pounds ; at nine years old, 240 pounds ; and at 
twelve years old, 314 pounds, 
