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methods. When such seeds have germinated the resulting 

 seedlings will clearly demonstrate the benefit of seed selection. 

 As soon as the young plants have reached a height of 7 to 8 

 inches it is time for the planter to pass through his fields, eliminat- 

 ing all plants that are defective, backward, or in any other way 

 undesirable. 



INCREASED SIZE AND PRODUCTIVENESS. 



Only a superficial observation is necessary to show the planter 

 that when a rubber tree is cultivated properly it re-acts to good 

 treatment. If the trees have good soil with sufficient moisture, 

 plenty of light and air, and no crowding competition with other 

 plants of their own or any other kind, they will grow quicker, re- 

 main healthier and more robust, and what is most important, they 

 will furnish a greater surface for tapping, than if exposed to the 

 vicissitudes of the natural struggle for life in the forest or in a 

 plantation where the trees stand too close. 



If we subject the trees to the best possible treatment according 

 to modern and improved methods of silviculture we will soon be 

 repaid for the additional care bestowed upon the plants. There 

 can be no doubt but that the size of the trunk can be considerably 

 increased by breeding and selection. There can be as little 

 uncertainty in regard to the possibilty of increasing the amount of 

 latex in the tree. These improvements take, however, some time, 

 and the rubber planter of to-day cannot immediately benefit by 

 the gradual advances made in this connection. To him it is more 

 important to take advantage of methods of selection which can be 

 put into practice on his plantation already started. On such a 

 place it is of the greatest consequence that all unproductive, sickly, 

 or otherwise unsatisfactory trees be destroyed. It does not pay to 

 cultivate trees which do not give a payable quantity of latex, and 

 it is a waste of land to keep the ground occupied by such trees, 

 which should be immediately replaced. 



In regard to the rapidity of growth and the size of the seedling 

 and the subsequent tree, it has long been conclusively proved that 

 the heavier seeds are far superior to the light ones. Experiments 

 conducted with a view of determining whether the size of the 

 seeds has any effect on the vigour of the plant, have shown that 

 plants grown from the heaviest seeds attain a greater size even if 

 they do not always germinate as rapidly as the smaller. It has 

 further been demonstrated that plants grown from the heaviest 

 seeds have a greater power of resistance to drought. 



To insure a good stand and a greater yield, none but the 

 largest and heaviest seeds should be selected, and of the seedlings 

 the most rapid growes, with the healtiest and most vigorous 



appearance. 



EXPERIMENTS IN IMPROVING CASTILLA. 

 So far, very few experiments have been made for the purpose 

 of improving the Castillo, rubber tree, or in order to ascertain the 

 growth of the seedling under different circumstances. A series 

 of such experiments were started in April and May of 1906, at 

 La Zacualpa Botanical Station in Mexico. The results of these 



