9 
a number are still left and are being tapped every year. In 1899 
Mr. O. H. Harrison, a coffee planter, bought Za.cualpa and im- 
mediately commenced planting rubber. The plantation which was 
later transferred to La Zacualpa Rubber Plantation Company, of 
San Francisco, California, is now probably the largest individual 
rubber plantation in the world, and will when ultimately completed 
consist of 12,000 acres under rubber. The variety grown is 
Castilla lactiflua Cook. In 1905 the first tappingjrom young trees 
was done, some 25,000 trees, between five and six years old, being 
lightly tapped. Six other rubber plantations have been started of 
late years in this district, two of which, juilapa and Zacualpa II, 
arealso under the general direction of'Mr. Harrison. These three 
sister plantations have now over 8,000 acres under rubber, varying 
in age from 6 months to 6^ years. 
In order to show how rubber planting is done in Mexico, and 
how we expect to handle the plantations and the crop of latex and 
rubber, I will describe somewhat in detail the conditions on La 
Zacualpa, and the methods which the management at my 
suggestion intends to adopt for the future. 
La Zacualpa Rubber Plantation. 
The estate which consists of 18,791 acres of land is situated 
on the coastal plains between the Sierra Madre and the Pacific 
Ocean, abfiut twelve miles from the latter. The land slopes very * 
gently towards the ocean, and the highest spot of the rubber plan- 
tation is about 50 feet above sea level. Tv» r o small rivers flow on 
the outskirt of the estate, which is intersected by several creeks. 
Part of the land is swampy, and is not planted in rubber. 
The plantation is laid out in square blocks, each containing 
27I acres. There are now over 200 blocks planted. Between the 
blocks are roads 24 feet wide. The trees are planted 400 to the 
acre, and admitting some failures, eachbloelt shoiild contain 10,000 
trees. On account of the lay of the land the planted blocks are in 
two tracts, one about twice the size of the other. All roads going 
lengthwise in the tract are called avenues and all cross roads 
streets. The longestavenue is nearly six miles through the planted 
rubber forest. 
The soil is an alluvial deposit of dark colour, of uniform grain 
size, without any interrupting strata of different physical . texture. 
In the places where borings have been made to ascertain the depth 
of the soil it has varied from 18 to 22 feet. Because of the physi- 
cal character of the soil the rise of water from below by capillarity 
is continuous and even in the dry season, which lasts six months, 
the trees do not suffer from lack of water. The root system of 
Castilla on this soil is superficial. In other districts, where the soil is 
stratified, I have found that the roots penetrate much deeper in order 
to reach the water-supply. Laboratory experiments have shown me 
that roots of Castilla seedlings in 42 days have grown to a length 
of 3 feet 4 inches in order to reach a water-supply, which by 
mechanical arrangement was gradually distanced from the roots 
in proportion to their growth. In the same time roots of Castilla 
seedlings in the undisturbed soil on Zacualpa did not reach a 
