a number are still left and are being tapped every year. In 1899 

 Mr. O. H. Harrison, a coffee planter, bought Zacualpa 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 



Costilla lactiflua Cook. In 1905 the first tapping from 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, 

 are also 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, about twelve miles from the latter. The land slopes very 

 gently towards the ocean, and the highest spot of the rubber plan- 



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 

 27f 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, each block should 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 longest avenue is nearly six miles through the planted 



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 

 Costilla 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 Castillo 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 Castillo 

 seedlings in the undisturbed soil on Zacualpa did not reach a 



