726 
THE TROPICAL AGEICULTURIST. [May 2, 1904. 
METHODS OF CLEAEING LAND FOB RUBBER PLANTING. 
The question o£ shade is also inv( Ived with that of 
the metiiod of clearing the land. It is au almost 
universal custom in tropical countries to clear land by 
burning the dried forest growth which has been cut 
down. In fact, the primitive aijriouliure of the natives 
of tropical regions could scarcely be conducted on any 
other basis. There is much loss of fertility by the des- 
truction of vegetable matter and humus, but the 
amount of labor required to thoroughly clear a piece of 
forest land in the Tropics is prohibitively great. The 
fire not only removes the tangled mass of brush, but 
it peiforms an even more useful service in killing 
the stumps and roots which would otherwise reoccupy 
the lind with new growth in a few weeks, and would 
r xaiia indt finitely to dispute possession with anything 
which might be planted. To grow a herbaceous crop 
on nnburned land under such conditions would bo 
extremely d.f&cult, bat a tree culture is much more 
feasible, though whether the method of partial clear- 
ing is to be generally advised is not so certain. The 
gain, if any, is more likely to be found in the sustained 
fertility of the soil than in any saving of labor in 
clearing and cleaning the land ; for although there may 
be a saving at first which will permit an enterprise to 
reach a paying basis sooner, yet there is in pros- 
pect a long and expensive struggle with the persistent 
natural vegetation rooted in the soil, Moreover, it 
should be recognized that the conditions under which 
a plantation is set out in a partially cleared forest are 
of necessity only temporary. Many of the forest trees 
will not long survive the unwonted exposure to greater 
dryness and heat and to the attacks of parasites. The 
thinning of the forest greatly increases the force o£ 
the wind against the remaining tall trees, and in fall- 
ing these will injure the rubber trees and will often 
require to be cut away not merely at one point, but at 
several points. Whatever the merits of the case from 
the standpoint of the stockholder, the plantation 
manager of the future is very likely to wish that his 
predecessors had adopted clean culture. The overhead 
shade which discourages the undergrowth will also 
discourage the rubber, and the decrease of such shade 
will increase the competition of the undergrowth with 
the rubber, 
THE IDEAL OF RUBBER CULTURE 
does not require a roof of shade over the rubber trees 
nor a dense growth of bushes and vines under them. 
The roof should be of Castilloa foliage, and the ground 
should be covered by a mulch of dead leaves and 
branches, which enrich the soil and assist in the reten- 
tion of moisture. 
THE TRUE CLIMATE OF HEVEA. 
The results of the writer's observations on Cistilloa 
were so much at variance with prevalent opinions con- 
cerning climatic requirements that the possibility of a 
similar error having been made with reference to 
Hevea naturally 8u>^gested itself, and various indica- 
tions like the preceding were found in the literature of 
the subject suggesting that this might prove to be the 
case. Shortly afterwards there appeared the following 
quotation from a paper written by Mr. H. A. Wickham, 
who made the original iutroduction of Hevea seeds 
from Brazil to British India, and whose testimony is 
so direct and conclusive that we need wonder only 
that so important a point should have been so long 
overlooked : 
But as all the stock of plants or seed available for 
the planting and cultivation of this tree in the Eastern 
Tropica are and will be cerived from direct lineal 
descendants of some or other of those 7,0C0 odd ori- 
ginally introduced by me at the instance of the govern- 
ment of India in 1876 77, it may be well if it be re- 
collected that their exnct place of origin was in 3° of 
south latitude, and to remember their natural con- 
ditions ihere. This the more so since a very general 
error seems to have obtained that swampy or wet 
lands are the fitting locality for the Hevea. This would 
eeem to have arisen in that the '■ explorer " of a few 
years' experience would have some of these trees 
pointed out to him {naturally in answer to inquiries) 
growing scattered along in the wet margins in going 
up the lower Amazon or tributaries, whereas 
THR TRUE FORESTS OF THE PAEA INDIAN RUBBER TREES 
lie back on the highlands, and those commonly seen 
by the inquiring traveller are but ill-grown trees which 
have sprung up from seeds brought do^fn by freshets 
from the mterior. 
As a matter of fact, tie whole of the Hevea which 
I procured for the government of India were the 
produce of large grown trees in the forest covering the 
broad plateaus dividing the Tapajos from the Maderia 
Eiver. The soil of these well-drained, wide- 
extending forest-covered table-lands is stiff, not re- 
markably rich, but deep and uniform in character, 
The Hevea found growing in these unbroken forests 
rivals all but the lirgest of the tress therein, attaining 
to a circumference of 10 feet to 12 feet in the bole. 
These forest plains having all the character of wide- 
spread table-lands occupy the space betwixt the great 
arterial river systems of the Amazon, and present an 
escarped face, which follows at greater or less distance 
and abuts steeply on the igapo or bagas, i.e., the 
marginal river plains subject to innundation by the 
annual ri«e of the great river. So thorough is the 
drainage of this highland that the people who annually 
penetrate into these forests for the season's working 
of the rubber have to utilize certain lianas (water- 
bearing vines) for their water sunply, since none is to 
be obtained by surface-well sinking, in spite of the 
jjcavy rainfall during a great part of the year. 
CONCLUDING 6UMJIARY OF THE BOOK. 
The culture of the Central American rubber tree 
has passed the experimental stage in the sense that 
the practicability of the agricultural production of 
rubber has been demonstrated, but on the other 
hand it has been ascertained that the tree may thrive 
where it will yield little or no rubber. Under favour- 
able natural conditions the culture of Castilloa elastica 
bids fair to become very profitable, but the experi- 
mental determination of the factors which influence 
the production of rubber has scarcely begun. 
In southern Mexico and Central America the re- 
gions well adapted to the culture of Castilloa are much 
more limited than has been supposed. The presence 
of wild Castilloa trees is not a sufficient evidence that 
a locality is suited to commercial rubber culture. 
Differences in the yield of rubber are not due merely 
to the existence of different species and varieties of 
Castilloa, but are also controlled by external conditions. 
The functions of the rubber milk in the economy 
of the plant are not well understood or agreed upon 
by botanists, but there are numerous reasons for 
holding that in Castilloa and many other plants it aids 
in resisting drought. 
A continuously humid climate is not necessary to 
the growth and productiveness of Castilloa ; the indi- 
cations are rather that the quantity of milk and the 
percentage of rubber are both increased by an alter- 
nation of wet and dry seasons. 
In its wild state Castilloa does not flourish in the 
denser forests, but requires more open situations. It 
is confined to forest regions only by the perishability 
Qf its seeds. 
Castillloa thrives better when planted in the open 
than in the dense forest ; even young seedlings are not 
injured by full exposure to the sun, providing that 
{he ground does not become too dry. 
The planting of Castilloa under shade or in partially 
cleared forests is to be advised only on account of 
special conditions or as a means of saving labor and 
expense. 
The loss of the leaves in the dry season may be 
explained as a protection against drought, and does 
not indicate conditions unfavourable to the tree or to 
the production of rubber. 
